General Lab Equipment Set up
When Setting up your laboratory equipment remember to follow a few safety guidelines:
- Read and follow the expected Manufacturer guidelines for installation, safety, equipment guarding and use.
- Read the Manufacturer information (books /guides) prior to purchase, set up and use.
- Use the equipment as designed (guarding, locking devices). Otherwise it is not the equipment appropriate for your task.
Before you purchase and install the equipment, know the equipment needs.
- Electrical
- Does the lab have the right electrical outlets for the equipment needs (i.e.: 240V vs 120V)?
- Do you have enough electrical outlets to satisfy the equipment plug ins?
- Do you have enough electrical available in your current lab or do you need to have facilities install more electrical sockets?
- Space
- is there enough room around the equipment in order to use it properly
- Will the equipment inhibit workflow or activity pathways?
- Ventilation
- Does the laboratory have the equipment ventilation needs available and in place before installation.
- Learn about the safety needs when using the equipment. (guarding, ventilation, PPE)
- Understand how to apply safety practices to your process.
Make sure your more hazardous pieces of equipment have a Standard Operating Procedure (SOP) written for its use and training your lab staff. Everyone who uses the equipment must be trained on the equipment and that training must be documented. Store the SOP with your laboratory safety documents in a easy to locate place and it is available at all times for all laboratory personnel to easily access.
Autoclave Safety 
No one should use an autoclave unless they have received recent instruction in autoclave procedure or are working under the direct supervision of an experienced autoclave worker.
Accidents are most likely to occur during the final operations of opening and unloading the autoclave, if they are to happen. When the pressure gauge reaches zero, wait one or two minutes before opening the autoclave. It is dangerous to begin opening the autoclave before the pressure gauge reaches zero. Long-sleeved, heat-resistant gloves should be worn- do not use if wet or have holes in them. Other protective equipment that should be worn to prevent being splashed by hot liquids are rubber apron and safety goggles, glasses, or faceshield.
Steam (Sterilizing) Autoclaves
The major hazards are:
- Burns resulting from physical contact with the structure of the autoclave.
- Steam burns arising from contact with steam issuing from the apparatus.
- Explosive breakage of glass vessels during opening and unloading.
- Burns arising from careless handling of vessels containing boiling liquids.
Top-Loading AutoclavesBeware of residual steam in the apparatus. Remove the lid cautiously keeping the body as far away from the apparatus as possible. Do not lean over the autoclave to examine the contents. Front-Loading Autoclaves
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Other Resources:
- Autoclave Safety Office of Radiation, Chemical & Biological Safety, Michigan State University
- Using Autoclaves Safely
, University of California-Berkeley - Autoclave Safety, University of Maryland
- Autoclave / Steam Generator Installation Requirements, University of Maryland
- Autoclave Safety, Cornell University
- Autoclave Safety, University of Mississippi
- Laboratory Safety Incidents: Autoclaves, AIHA Laboratory Health & Safety Committee
- Autoclave Safety, University of Alabama at Birmingham
- Safe and Effective Use of Autoclaves, University of Pennsylvania
- Autoclaves, Iowa State University
Fume Hoods: Procedures and Practices
- General
- Equipment Use
- Good Work Practices
- Waste Disposal
- Good Housekeeping Practices
- Proper Sash Use
- Fume Hood Testing and Maintenance
General
Laboratory fume hoods serve to control exposure to toxic, offensive or flammable vapors, gases and aerosols. Fume hoods are the primary method of exposure control in the laboratory.
Use the right hood for the job:
- General Purpose Hoods:
- Standard Fume Hood
- Bypass Hood, or Constant Volume Hood
- Variable Air Volume (VAV) Hood
- Auxiliary Air Supplied Hood (Note: At UWM, found only in the Chemistry Building)
- Radioisotope Hood–These hoods have been authorized by Radiation Safety for use with volatile radioactive materials.
- Biosafety Cabinet–Specialized hoods to prevent or minimize the exposure of humans or the environment to biohazardous agents or materials.
- Perchloric Acid Hoods must be used when working with PCA (e.g., acid digestion procedures). These hoods prevent the formation of perchlorates which could lead to explosions. They are constructed with special materials and have water-wash capability.
- Hoods are labeled for special use when practical.
Equipment Use
- Place apparatus and equipment as far back as possible in hood for safety and optimal performance. Equipment should be placed a minimum of 8 inches inside the hood. Keep electrical connections outside of hood.
- Ensure that equipment or materials do not block the baffle vents in the back of the hood.
- When using a large apparatus inside the hood, place the equipment on blocks, when safe and practical, to allow air flow beneath it.
- Do not place electrical apparatus or other ignition sources inside the hood when flammable liquids or gases are present. Keep in mind that liquids with low flash points may ignite if they are near heat sources such as hot plates or steam lines.
Good Work Practices
- When using the fume hood, keep your face outside the plane of the hood sash and remain alert to changes in air flow.
- Work at least 6 inches back from the face of the hood. A stripe on the bench surface is a good reminder.
- Always use splash goggles, and wear a full faceshield if there is possibility of an explosion or eruption.
- Do not make quick motions into or out of the hood, use fans, or walk quickly by the hood opening. All will cause airflow disturbances which reduce the effectiveness of the hood. A demonstration of the effects of walking past the fumehood is demonstrated in this video clip from the EHS Department at the University of Nevada-Reno.
- Substitute less hazardous or less volatile chemicals where possible;
- Look for process changes that improve safety and reduce losses to the environment (e.g. more accurate chemical delivery systems vs. pouring volatile chemicals from bottles); and,
- Develop a process to evaluate research proposals ahead of time for potential emissions and look for opportunities to reduce them.
Waste Disposal
Do not use the hood as a waste disposal mechanism. Apparatus used in a hood should be fitted with condensers, traps, or scrubbers to contain and collect waste solvents, toxic vapors or dust. Please contact staff in UWM’s Hazardous Waste Program for additional information on waste disposal or refer to the following webpage: Hazardous Waste Disposal Information.
Good Housekeeping Practices
- Limit chemical storage in fume hoods. Keep the smallest amount of chemicals in the hood needed to conduct the procedure at hand;
- Store hazardous chemicals such as flammable liquids in an approved safety cabinet;
- Keep caps on chemical reagent bottles tight and check fitting on laboratory glassware to minimize vapor loss;
Always use good housekeeping techniques to maintain the hood at optimal performance levels. Excessive storage of materials or equipment can cause eddy currents or reverse flow resulting in contaminants escaping from the hood.
Proper Sash Use
- Do not remove sashes from sliding sash hoods. The hood should be kept closed, except when working within the hood is necessary.
- Use sliding sash for partial protection during hazardous work.
- Do not remove the sash or panels except when necessary for apparatus set-up. Replace sash or panels before operating.
- Keep the slots of the hood baffles free of obstruction by apparatus or containers. See video clip (courtesy of University of Nevada EHS Department.)
- Keep the hood sash closed as much as possible to maximize the hood’s performance. Keep the sash closed when not in use to maximize energy conservation. This video clip (courtesy of the University of Nevada) demonstrates the effects of raising and lowering the sash height.
Demonstration of fume hood capture efficiency with the sash in the full-open position. Notice escape of the visualization smoke from the bottom of the hood. |
Notice the improved capture efficiency with the sash in the partially-closed position. |
Fume Hood Testing and Maintenance
Hoods should be evaluated by the user before each use to ensure adequate face velocities and the absence of excessive turbulence.
In case of exhaust system failure while using a hood, shut off all services and accessories and lower the sash completely. Leave the area immediately.
The required face velocity is 100 feet per minute (0.5 m/sec). This velocity is capable of controlling most low-velocity cross drafts and turbulence created by normal working practices at the face of the hood. All hoods should have a sticker designating the maximum safe sash height. Keep the sash at the appropriate level to ensure optimal face velocity.
The low flow hoods in the North Tower of the Chemistry Building were evaluated at installation using the ASHRAE 110 Method of Testing Performance of Laboratory Fume Hoods. In this sophisticated test, a tracer gas (sulfur hexaflouride) is released at a known rate inside the hood. Samples are taken in the breathing zone of a mannequin standing at different positions in front of the hood. The DILHR mandated pass criteria is 100 parts per billion (ppb) tracer at the breathing zone of the mannequin. As with conventional style hoods, keep the sash at the appropriate level as indicated by the test label to ensure optimal hood performance. The objective is to minimize the sash opening to achieve proper containment.
Regular testing of the fume hood should be done by Facility Services or University Safety and Assurances staff to ensure that it is operating properly. Hoods are labeled to indicate the last inspection date. If your hood has not been tested within the past year, please contact Zack Steuerwald, x5808.
State of Wisconsin Department of Safety and Professional Services states :
| SPS 332.24
(6) VENTILATION FOR LABORATORY FUME HOODS.
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The OSHA Laboratory Standard (29 CFR 1910.1450) does not specify safe hood operation, flows or face velocities. However, it does mandate a chemical hygiene plan and lists requirements for the plan, including “a requirement that fume hoods and other protective equipment are functioning properly and specific measures that shall be taken to ensure proper and adequate performance of such equipment.” The non-mandatory Appendix A states: “General air flow should not be turbulent and should be relatively uniform throughout the laboratory, with no high velocity or static areas; airflow into and within the hood should not be excessively turbulent (200); hood face velocity should be adequate (typically 60-100 lfm)”
Additional Resources
Ductless Fume Hood Policy
Occasionally, the Department of University Safety & Assurances is asked to approve the purchase of ductless fume hoods for use in labs. The hoods are designed to remove hazardous fumes and vapors from the work area as the exhausted air passes through an absorbent, such as activated charcoal.
The system’s appeal is largely economic because it does not require the expensive ductwork that traditional hoods need to exhaust fumes to the outside. However, in practice these hoods require constant attention and often do not provide adequate face velocity. In many cases, the filter is designed for specific chemicals and will not protect against the variety of chemicals used in a typical university laboratory.
Ductless fume hoods are plagued with the problems associated with “breakthrough” and with desorption of vapors from the absorbent. The user will also face expenses to replace charcoal filters and to dispose of the expended filters, which may be classified as hazardous waste. Estimated cost of filter disposal will be about $100 each. Therefore, depending upon the amount of use, annual maintenance costs to the owner could exceed several hundred dollars.
We do not believe that the hoods provide reliable protection against chemical exposure, and we think they may, in fact, give workers a false sense of security. Therefore, we strongly recommend against and, except in extremely rare circumstances, will not approve the use of ductless fume hoods. Moreover, we do not provide inspection or certification for ductless fume hoods.
If a department insists on purchasing a ductless fume hood, it should only be used with small amounts of low-toxicity chemicals, and the hood should be clearly labeled to indicate that it may not provide suitable protection from hazardous chemicals.
Laser Safety
Laser is an acronym for “light amplification by stimulated emission of radiation.” Radiation in this case occurs in the portions of the electromagnetic field with insufficient energy to induce ionization or breaking up on the atom (i.e., it is non-ionizing). Non-ionizing radiation occurs in the radio frequency, microwave, infrared visible and ultraviolet ranges.
Lasers operate in two modes: pulsed (e.g. Q-switched lasers) and continuous wave (CW). Generally, pulsed lasers are more hazardous than CW lasers. Lasers using C02 and certain other materials emit beams that are not visible to the eye, hence they are particularly hazardous.
Biological damage caused by lasers includes thermal burns, photochemical burns and retinal injury. Electrical safety and fire are also important concerns.
In the use of a laser, safety procedures must be established and followed so that protection is provided for students, teachers, workers, visitors, bystanders and passersby.
Hazards may include:
- Vaporized target material from high-energy laser cutting, drilling and welding operations.
- Gases from lasers
- Gases from cyrogenic coolants
- Ultraviolet infrared radiation
- Electrical hazards–cables between the power supply and laser head must be properly selected and placed and the capacitor system safeguarded.
All electrical equipment must be well-maintained to prevent shocks and burns. Energy sources for lasers are essentially high-voltage equipment. Capacitors must be de-energized before cleaning or any repairing. All voltage on capacitors must be removed before leaving equipment. Interlocks must be provided to prevent access to components of high-voltage currents. Fire buttons must be remote from the charge and hold buttons to prevent accidental discharge of a laser. All ultraviolet and infrared radition must be shielded.
Hazard controls in the operation of lasers are:
- Do not look into the primary beam or at reflections of the beam.
- Avoid aiming the laser with the eye to prevent looking along the axis because of the hazard of reflection.
- If possible, work with lasers should be done in areas of high general illumination to keep pupils constricted.
- Proper safety glasses should be worn to filter out specific injurious frequencies of the unit.
- Terminate the laser beam with material that is non-reflective and fire resistant.
- Provide adequate clear space around the laser path.
- Provide protection from electrical shock from the potentially dangerous electrical sources of high and low voltage.
- High-voltage rectifiers may generate Xrays and require protection.
There are many special precautions that must be taken from the particular lasers as high-powered pulsing lasers and low-powered gas and semiconducted systems. Carbon dioxide and nitrogen lasers are fire hazards.
Any room where a laser is located must be adequately marked on the entering door and in the room so that everyone (students, faculty, staff, and/or visitors) is aware of its presence.
Security of the equipment against inadvertent intrusion must always be considered when operating a laser.
At least two people should be present at all times when lasers are in operation. Under no circumstances should a room containing an active laser be left unattended or unlocked.
Ventilation of the room must be considered to remove any accumulation of hazardous gases or fumes that are generated in the operation of the laser.
All personnel in the laser area should be informed about the potential eye hazard of accidental exposure to the beam. It is the responsibility of the project supervisor to give each person concerned a copy of these rules and ensure that all safety precautions are observed.
More detailed information is given in the American National Standard for the safe use of lasers (ANSI Z136.1-1973) and OSHA 29 CFR 1910.32 for eye protection; 21 CFR 1040 (U.S. Food and Drug Administration’s control of commercial devices); and OSHA’s 29 CFR 1926.54 construction uses. These standards cover facilities, program requirements and safety measures. It is strongly recommended these standards be reviewed as supplementary information to be followed.
UWM Resources:
Other Resources:
- Laser Hazards, OSHA Safety and Health Topics
- Laser Hazards, OSHA Technical Manual
- Laser Safety Information Bulletin, Laser Institute of America, (Covers concerns and issues related to laser safety for the new laser user.)
Laser Safety Manual
Manual in .pdf format for printing purposes.
1) Purpose and Scope:
The purpose of this guide is to establish Information and safety measure for working with lasers and laser systems the research and instructional laboratories. This document is developed and based on ANSI Z136.1- 2014 Standard American National Standard for Safe Use of Lasers and serves as a guidance document for faculty, staff and Students working with lasers at the University of Wisconsin – Milwaukee. This guide provides recommendations for the safe use of lasers and laser systems that operate at wavelengths 180nm and 1000µm.
2) Roles and Responsibilities:
The University Safety and Assurances (US&A) department at UW-Milwaukee manages the research laser safety program. A member of the US&A staff serves as the Laser Safety Officer (LSO) and works closely with the laser labs and US&A to establish and maintain adequate policies and programs for the control of laser hazards
3) Procedures:
i. Laser Registration:
It is the responsibility of the Principal Investigator (PI) to register all lasers under their authorization with US&A. Contact the lab safety coordinator to register your lasers. officer The Registration Form is available on the US&A Website.
Laser systems containing embedded lasers are exempt from registration. However, the LSO should be notified when such a system is acquired to perform laser hazard evaluation, as there may be the situations where protective housings are removed, or interlocks are defeated and the possibility for beam hazards exist.
Once the lasers are registered, the LSO will contact the PI and work together to have all laser safety requirements and control measures in place. The PI, lab and laser details are used to create an SOP for laser use.
ii. Laser Safety Training:
All Staff and students using lasers in research and classrooms shall take the online “General Laser Safety Training” prior to any laser use. The training is available on the US&A website.
Besides the general training, each operator must be trained on laser specific safety regarding the procedure, equipment used and emergency procedure before operating 3B or Class 4 lasers/ laser devices by the PI or appropriate designee. The laser specific safety training should be included as part of the standard operating procedure and documentation of that training is expected.
iii. Medical Surveillance
Complete and accurate records of all medical examinations (including specific test results) should be maintained for all personnel included in the medical surveillance program. Records should be retained for at least 30 years.
iii(a) Pre-assignment Medical Exams
A baseline eye exam is highly recommended but not required for users of class 3B, and Class 4 lasers/ laser system as stated in ANSI Z136.1-2014. A Baseline exam is used to establish a baseline against which ocular damage may be measured. Ocular histories, visual acuity measurement and selected examination protocols may be required dependent on the specific laser radiation wavelength. These examinations shall be performed by or under the supervision of, an ophthalmologist, optometrist or other qualified physician as specified in ANSI Z136.1 The individual Department or laboratory is responsible for all fees, the source should be determined prior to the exam. A Baseline exam is highly recommended for individuals that have worked previously with Class 3B and Class 4 lasers to confirm pre-existing eye conditions prior to beginning new laser tasks.
iii (b) Periodic Eye Examinations
Periodic eye examinations are not required. No chronic health problems have been associated with laser work.
iii(c) Termination Eye Examinations
Termination eye exams are not required for all users of class 3B and 4 lasers.
iii(d) Incident-Related Eye Exams
In the event of any accidental or suspected eye exposure to laser radiation, a thorough eye examination shall be conducted as specified by the Employees insurance supported ophthalmologist, optometrist or other qualified physician as specified in ANSI Z136.1 as soon as possible following the incident/ exposure. In addition to the acute symptoms, consideration shall be given to the exposure wavelength, emission characteristics and exposure situation to ensure appropriate medical referral For Incident related eye exams, it is important that immediate care be administered promptly and as such the most immediate care should be sought. An incident report, Employers first report of Injury or Disease and Supervisors Accident analysis and prevention report should be filed. The forms can be found on the US&A website Forms page.
Exams should include the following elements:
- Ocular History: The past eye history and family histories are reviewed. Any current complaints concerned with the eyes are noted. Inquiry should be made into the general health status with a special emphasis upon systemic diseases which might produce ocular problems. Use of photosensitizing medications, such as phenothiazines and psoralens, lower the threshold for biological effects in the skin, cornea, lens and retina of experimental animals exposed to ultraviolet and near ultraviolet radiation. Aphakic individuals would be subject to additional retinal exposure from near ultraviolet and ultraviolet radiation. Unless chronic viewing of these wavelengths is required, there should be no reason to deny employment to these individuals
- Visual acuity: Visual acuity for far and near vision should be measured with some standardized and reproducible method
- Macular function: A Spectral Domain OCT or in absence of such, an Amsler grid or similar pattern is to be used to test macular function for distortions and scotoma
- Dilated Examination of the Ocular fundus: Points to be covered are the presence or absence of opacities in the cornea; media; the sharpness of outline of the optic disc; the color of the optic disc; the presence or absence of a well-defined macular and any retinal pathology (hyper-pigmentation, depigmentation, retinal degeneration, exudate, as well as any induced pathology associated with changes in macular function). Even small deviations from normal should be described and carefully localized. The use of Spectral Domain OCT provides documentation and is the preferred means for doing so.
4. Hazard Evaluation/ Standard Operating Procedure
An assessment should be performed for every laser lab to identity hazards that could arise from the laser system and laser use settings. The following aspects should be taken into consideration while evaluating the lasers
- The laser or laser systems capability for causing injuries
- The environment where the laser is manipulated
- The people who may use or be exposed to the laser beam
- US&A Can assist in performing the hazard evaluation
A written Standard Operating Procedure (SOP) is required for all Class 3B and Class 4 lasers or laser system. The SOP should be reviewed and followed by all uses and must be available in the lab for easy access. The Manufacturers operation manual can be included in the SOP but is not a substitute for an SOP. SEE the LASER SOP form.
The SOP must include the following:
- Laser details
- Laser system set-up
- Intended laser application
- Operation Procedures
- Control Measures
- Maintenance Procedure
- Beam and non-beam hazards
- Personal Protective Equipment PPE requirements.
5. Laser Safety.
Laser is an acronym for Light Amplification by Stimulated Emission of Radiation. Radiation in this case occurs in the portions of the electromagnetic field with insufficient energy to induce ionization or breakup of the atom (i.e., it is non-ionizing). Nonionizing radiation occurs in the radio frequency, microwave, Infrared visible and ultraviolet ranges. The radiation emitted by lasers is unique. It is mono chromatic (one color), it is coherent (all the wavelengths are in Phase), and it is directional (all waves travel in the same directions, parallel to one another) laser light beams are very narrow and can be focused or concentrated on one tiny spot. Lasers are very bright because they contain an intense amount of radiant energy. Lasers operate in two modes: Pulse (e.g., Q-switched lasers) and continuous wave (CW). Generally, pulsed lasers are more hazardous than CW lasers. Lasers using CO2 and certain other materials emit beams that are not visible to the eye; hence they are particularly hazardous.
Biological damage caused by lasers includes thermal burns, photochemical injuries, and retinal injury. Electrical safety and fire are also important concerns. Standards governing lasers are ANSI Z136.1 and OSHA 29 CFR 1910.32 for eye protection; 21 CFR 1040 (the US food and Drug Administration control of commercial devices); and OSHA’s 29 CFR 1926 .54 (construction uses) These standards cover facilities, program requirements and safety measures.
6. Laser Hazard Classification
The basic approach of all laser safety standards has been to classify lasers by their hazard potential, which is based upon their optical emission. The next step is to specify control measures which are corresponding with the relative hazard classification. in other words, the laser is classified based upon the hazard it presents, and for each classification a standard set of control measures applies. In this manner, unnecessary restrictions are not placed on the use of many lasers which are engineered to assure safety. To determine a laser’s classification, refer to the label, operator’s manual or perform hazard classification analysis. Use of the manufacturer certified classification whenever possible
This philosophy has given rise to a number of specific classification schemes such as the one employed in the American National Standards Institutes (ANSI) Z136.1 Safe Use of Lasers (2014) standard. The ANSI scheme has four hazard classifications. The classification is based upon the beam output power or energy from the laser (emission) if it is used by itself. If the laser is a component within a laser system where the raw beam does not leave the enclosure, but instead a modified beam is emitted, the modifies beam is normally used for classification. The classification scheme is used to describe the capability of the laser or laser system to produce injury to personnel. the higher the classification number, the greater the potential hazard. Brief description of each class are as follows:
- Class 1 Laser System.
Considered to be incapable of producing damaging radiation levels during operation and exempt from any control measures. Class 1 lasers are termed “no risk’ lasers because they are not capable of emitting hazardous laser radiation levels under any operation or viewing conditions. The exemption from hazard controls strictly applies to the emitted laser radiation hazards and not to other potential hazards. An Example of a Class 1 lasers system is one that includes an embedded higher-class laser but during normal operation presents no laser radiation hazard to the user. Most lasers by themselves do not fall into the Class 1 category, but when the laser is incorporated into a consumer good or office machine the resulting system may be Class 1.
i) Class 1M Laser System
A laser can be classified as Class 1M if the power that can pass through the pupil of the naked eye is less than the Accessible Emission Limit (AEL) for Class 1, but the power that can be collected into the eye by typical magnifying optics (as defined in the standard) is higher than the AEL for Class 1 and lower than the AEL for Class 3B.
Considered to be incapable of producing damaging radiation levels during operation unless the beam is viewed with collection optics (i.e., telescope) and is exempt from any control measure other than to prevent potentially hazardous optically aided viewing.
ii) Class 2 Laser System
Class 2 lasers have low power and emit visible light. They will cause harm if viewed longer than 1000 seconds or if they have enough power will cause pain when viewed for longer than 0.25seconds (the eye aversion response time).
All Class 2 lasers Emits in the visible portion of the spectrum (400nm-700nm) and eye protection is normally afforded by the aversion response. Aversion response is Closure of the eyelid, eye movement, pupillary constriction, or movement of the head to avoid an exposure to a noxious or bright light stimulant. In this standard the aversion response to an exposure from a bright, visible, laser source is assumed to limit the exposure of a specific retinal area to 0.25 s or less. Class 2 lasers are often termed “low power” or “low risk’ laser systems, are visible lasers which are only hazardous if the viewer overcomes their natural aversion respond to bright light and continuously stares into the source. While such an event is remote, it could just as readily occur as blinding oneself by forcing oneself to stare at the sone form more than 10-20 seconds. Precautions are required to prevent continuous staring into the direct beam. Momentary exposure (<0.25 second) occurring in an unintentional viewing situation is not considered hazardous. Examples of Class 2 lasers are code readers in food stores, laser tag guns, and positioning lasers in medical applications. This class is further redefined dependent on whether the laser is Continuous Wave (CW) or pulsed. Visible (400-700nm) Continuous Wave (CW) laser devices that can emit a power exceeding the limit for Class 1 for the maximum possible duration inherent to the design of the laser or laser system, but not exceeding 1mW.
Visible (400-700nm) repetitively pulsed laser devices that can emit a power exceeding the appropriate limit for Class 1 for the maximum possible duration inherent to the design of the laser device but not exceeding the limit for the 0.25 second exposure.
iii) Class 2M Laser System
These are visible lasers. This class is safe for accidental viewing with the naked eye, as long as the natural aversion response is not overcome as with Class 2 but may be hazardous (even for accidental viewing) when viewed with the aid of optical instruments, as with class 1M.
Emits in the visible portion of the spectrum (400 to 700 nm) laser or laser system that is not indented for intra-beam viewing and does not exceed the exposure limit for 1000 seconds of viewing time. Eye protection is normally afforded by the aversion response, but potentially hazardous if viewed with certain optical aids.
iv) Class 3R Laser System
Class 3R lasers or laser systems would not normally injure the eye if viewed for only momentary periods (within the aversion response of 025 seconds) with the unaided eye but may present a greater hazard if viewed with collecting optics. Those lasers are labeled with a CAUTION Label. Another Group of 3R lasers have DANGER labels and are capable of exceeding the permissible exposure levels for the eye in 0.25 seconds and still pose a minimal risk of injury.
Potentially hazardous under some direct and specular viewing conditions if the eye is appropriately focused and stable, but probability of an actual injury is small.
v) Class 3B Laser System
Class 3B lasers or laser systems are those that can produce a hazard if viewed directly. This includes intra-beam viewing of specular reflections. Medium powered laser that may be hazardous under direct and specular viewing conditions but is normally not a diffuse reflection or fire hazard. Normally, Class 3B lasers will not produce a hazardous diffuse reflection. Class 3B is broken into four different frequency and energy regions:
- Infrared (1.4 µm to 1000µm) and ultraviolet (200nm to 400nm) laser devices. Emits radiant power in excess of the Class 1 limit for the maximum possible duration inherent to the design of the laser device. Cannot emit an average radiation power of 0.5 W or greater for viewing times greater than 0.25 seconds, or a radiant exposure of 10 J/cm2 within an exposure time of 0.25 seconds or less
- Visible (400-700nm) CW or repetitive pulsed laser devices. Produce a radiant power in excess of the Class 1 assessable exposure limit for a 0.25 second exposure (1nW for a CW laser). Cannot emit an average radiant power of 0.5 W or greater for viewing time limits greater than 0.25 seconds.
- Visible and near-infrared (400nm-1400nm) pulsed laser devices. Emit a radiant energy in excess of the Class 1 limit but cannot emit a radiant exposure that exceeds that required to produce a hazardous diffuse reflection.
Near-infrared (700nm to1400nm) CW devices or repetitively pulsed laser devices. Emit power in excess of the exposure limit the Class 1 for the maximum duration inherent in the design of the laser device. Cannot emit an average power of 0.5 W or greater for periods in excess of 0.25 seconds.
vii) Class 4 Laser System
High-Powered laser systems normally have an average outputs of greater than 500 Milliwatts, present a “high risk” of injury and can Cause combustion of flammable materials. This class includes pulsed visible and near IR lasers capable of producing hazardous diffuse reflections, fire, and skin hazards. Also, systems whose diffuse reflections may be eye hazards and direct exposure may cause serious skin burns. Class 4 lasers normally require restrictive warning labels and even more restrictive control measures (e.g., safety goggles, interlocks, warning signs, etc.). Class 4 lasers are further divided int two sub-classes base on frequency (i.e., Wavelength):
- Ultraviolet (200nm to 400nm) and infrared (1.4 µm to 1000 µm) laser devices. Emit an average power of 0.5 W or greater for periods greater than 0.25 seconds, or a radiant exposure of 10J/cm2 within an exposure duration of 0.25 seconds or less.
- Visible (400-700nm) and near-infrared (700nm to 1400 nm) laser devices. Emit an average power of 0.5 W or grater for periods greater than 0.25 seconds or a radiant exposure in excess of that required to produce a hazardous diffuse reflection.
- Hazard to the eye or skin from the direct beam, and sometimes from a diffuse reflection, and can also be a fire hazard. May also produce laser generated air contaminants (LGACs) and hazardous plasma radiation.
https://www.laserpointersafety.com/laserclasses.html
7) Laboratory Controls
Although accidents occur, laser systems are designed to be safe. The objective of a safe design is to ensure that the equipment controls, interlocks, beam enclosures, shutters, and filters are appropriate to the hazard potential of the system and to the experience level of the personnel operating and servicing the equipment. The goal of restricting human access to hazardous levels of optical radiation or live electrical currents, is usually achieved by permanent interlocks which are designed to be failsafe or failure proof. For example, extensive use is made of mechanical-electrical interlocks in this instance, the lateral or rotary movement of a hinge or a latch activates a switch which is in the the power circuit for the laser. The design of interlock ensures that even partial opening of the panel to a point where hazardous radiation can be emitted from the open results in shutdown. Additionally, positive-activated switches (e.g., ‘dead-man’ type) are often used to ensure operator alertness and reduce the risk of accidental firing.
For certain applications laser projection are used. In such instances, it is often desirable to alter the output beam pattern of a hazardous laser so a safe pattern results. Methods to accomplish this include the use of wide beams, unfocused beams, or beam diffusers. A CW laser with an emergent beam diameter of 10-20 cm is less hazardous than a laser of the same power with a 2nm beam diameter. An unfocused beam is safer because the biological effect depends upon the total power and the beam irradiance. A diffuser is used to spread the beam over a greater area and thus change the output from intra-beam viewing to an extended source. The actual classification of the laser would not change unless the output beam diameter were greater than 80mm. In theory, a diffuser would change a Class 4 laser into a Class 1 or 2 laser; however, in practice, diffusers are usually effective in reducing the hazard classification approximately one class. The safety applied to indoor laser installations usually depends on the class of laser.
- Class 1 (exempt) laser system do not require much control. The user may opt to post the area with a low power laser sign. The laser should be labeled with the beam characteristics. Some Class 3B or Class 4 laser system are embedded in closed devices and the device is then classified as a Class 1 system. For such systems, the manufacturer normally installs enclosure interlocks and service panels to prevent tampering. Additionally, persons using the system must receive training on the hazards and controls for that laser before being designated and ‘authorized” operator.
- Class 2 (low power) lasers require a few more controls. This is the first instance when, in some applications, posting the area with a caution sign becomes mandatory. Additionally, non-reflective tools are often used to reduce reflected light. Controls applied to the system include the blocking the beam and at the end of its useful path, controlling spectator access to the beam, and controlling the use of view ports and collecting optics.
- Class 3R lasers are the most common laser system and are potentially hazardous when using optics. Thus, posting of the area with either CAUTION or DANGER signs depends upon the irradiance. Personnel maintaining such systems or conducting research with unenclosed beams should be given a baseline eye exam. Control measures are concentrated on eliminating the possibility of intra-beam viewing by:
- Establishing alignment procedures that do not include eye exposure
- Use Proper safety eyewear if there is a chance that the beam or a hazardous specular reflection will expose the eyes
- Control of Fiber optic emissions
- Establishment a normal hazard zone for outdoor use.
- Class 3B laser systems are potentially hazardous if the direct or secularly reflected beam is viewed by the unprotected eye, consequently eye protection may be required if accidental intra-beam viewing is possible. It is at this point that many of the suggested controls become mandatory. Besides posting the area with DANGER signs, other control measures include:
- Permitting only experience personnel to operate the laser and not leaving an operable laser unattended if there is a chance and unauthorized user may attempt to operate the laser.
- Baseline eye exam required for maintenance and research applications.
- Control of spectators.
- Laser power controlled by a key-operated master switch.
- Mounting the laser on a firm support to assure that the beam travels along the intended path.
- Assuring that individual so not look directly into laser beam with optical instruments unless an adequate protective filter is present within the optical train.
- Eliminating unnecessary specular (mirror-like) surfaces from the vicinity of the laser beam path or avoid aiming at such surfaces.
- Class 4 laser systems that are pulsed visible and IR-A laser are hazardous to the eye from direct beam viewing and from specular (and sometimes diffuse) reflections. Ultraviolet, infrared, and CW visible laser present a potential fire and skin hazard. These ‘high power” lasers present the most serious of all laser hazards. Besides presenting serious eye and skin hazards, these lasers can often ignite flammable targets, create airborne contaminants, and usually have a potentially lethal, high-current/ high voltage power supply. The following rules should be carefully followed for ALL high-power lasers:
- Enclose the entire laser beam path if at all possible. If done correctly, the laser’s status could revert to a less hazardous laser classification.
- Safety interlocks at the entrance of the laser facility shall be constructed so that unauthorized personnel are not allowed access to the area while the laser is capable of emitting laser radiation at Class 4 levels.
- Ensure that all personnel wear adequate eye protection, and if the laser beam irradiance represents a serious skin or fire hazard that that a suitable shield is present between the laser beam(s) and personnel
- Laser Electronic firing system for pulsed lasers shall be designed so that accidental pulsing of a stored charge is avoided. Additionally, the firing circuit shall incorporate a fail -safe (e.g., dead man) system.
- Good ambient illumination is essential when eye protection is being worn. Light colored, diffuse surfaces assist in achieving this goal.
- Using remote firing and video monitoring or remote viewing through a laser safety shield where feasible.
- Because the Principal hazard associate with high -powered CW far -infrared (e.g., CO2) lasers is fire, a sufficient thickness of earth, firebrick or other fire-resistant materials should be provided as a backstop for the beam.
- Reflection of far-infrared laser beams should be attenuated by enclosure of the beam and target area or by eyewear constructed of a material which is opaque to laser wavelengths greater than 3 µm (e.g., plexiglass). Remember, even dull metal surfaces may be highly specular in far-infrared laser wavelengths.
(vi) A laser safety operational procedure manual is a document used to describe both a systems potential hazards and controls implements to reduce the risk of injury from the laser. It may detail specific administrative controls such as signs or lights, engineering controls such as interlock, enclosures, grounding, and ventilation, required personal protection such as eyewear or clothing, and training with regard to laser safety or chemical safety. As a minimum an operational safety procedure must be promulgated for: Class 4 laser systems
- Two or more Class 3 lasers with different operators and no barriers
- Complex or non-conforming interlock systems or warning devices
- Modification of commercial lasers which have decreased safety
- Class 2,3, or 4 laser systems used outdoors or off site.
- Beams of Class 2,3, and 4 lasers which must be viewed directly or with collecting optics near beam.
Requirements by LASER Class
Class Control Measures Training Engineering Controls
1 Not Required Not Required Not Required
1M Required Application Dependent Application dependent
2 Not Required Not Required * Not Required*
2M Required Application Dependent Application Dependent
3R Not Required Not Required* Not Required*
3B Required Required Required
4 Required Required Required
certain uses of class 1Mor 2M lasers may require hazard evaluation and/or manufacturers information in regard to the application of use
*Not required except for condition of intentional intrabeam exposure application
8). Laboratory Controls
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- Warning Signs and Labels
The warning sign warns the presence of a laser hazard inside the lab or space. Appropriate warning signs conveying the severity of hazards pertinent to the class of laser should be posted at the entrance of the laser lab
a) Lighted Warning Sign
The entrance to laser labs with open beam Class 3B and Class 4 laser shall have a lighted warning sign on when the laser is operating. For any new laser lab, installing the lighted warning sign will be part of the lab remodeling process. For existing labs, the SSO, Lab, Department and Facilities electrical show should work together to initiate the process.
b) Written Warning Signs and Labels
Warning signs and labels are used to alert workers. Placarding of potentially hazardous areas should be accomplished for Class 3B and Class 4 lasers. Appropriate warning labels shall be affixed permanently to all Class 2, 3, and 4 lasers and laser systems. Class 2 and 3R usually use CAUTION signs/labels while Class 3B and 4 use DANGER signs/labels. Examples of such warning signs are seen below
Laser Warning Signs
Class 2 Class 3R
Class 3B Class 4
i) Except for Class 1 lasers, all other lasers/ laser system should have appropriate warning labels. The labels shall be affixed to a conspicuous place on the laser housing or control panel.
ii) The labels shall indicate the class of laser/laser system, wavelength, maximum power output, pulse duration (if applicable), and the precautionary instruction or protection action required for using the system.
8) Safety Precautions – Control of Associated Hazards
The wide variety of equipment used in conjunction with lasers often have associated safety problems.
- Access Controls For any Class 3B or Class 4 laser lab, the access to the lab should be limited on only authorized personnel. It can be maintained through room interlocks or entryway controls. For entryway controls, a key control door, blocking barriers, screen, laser curtain, etc. can be used to prevent the laser radiation from exiting the area at levels above the applicable Maximum Permissible Exposure (MPE). If the same lab is use for other functions by other researcher, then the laser within the lab has to be secured with a key switch only accessible by authorized personnel.
- Substitution of alternate control measures (Class3B and Class 4)The ANSI Z136.1 establishes the LSO’s authority to substitute the control measures, (engineering controls) specific in the standard for Class 3B and Class 4 lasers with administrative or other alternative controls measures that provide the equivalent protection.
- Each research laser lab is unique and designed for a specific purpose. As such, not all the engineering controls measures specified in the standard may be feasible to implement. The LSO will view controls used in laser lab and may approve alternative controls.
- General Safety Procedure for working with Class 3B and Class 4 lasers
- Only training and authorized individuals should be permitted to operate the laser
- Post an appropriate laser hazard warning signs at each entrance o laser use areas.
- Secure the laser from operation by unauthorized personnel. A key switch should be used if unauthorized personnel may gain access to the laser. Entrance controls (e.g., warning lights, interlocks, key door, laser barriers) are required
- Remove unnecessary optics from the beam path.
- Always keep the beam path below the eye level for either sitting or standing position.
- Enclose as much of the beam as is practical.
- Never look directly int the laser beam with optical instrument without an adequate filter.
- Use proper laser eyewear if applicable MPE may be exceeded.
- Use remote firing of the Class 4 laser, video monitoring, or remote viewing whenever feasible,
- Have all windows, doorways, and open portals in an indoor facility covered if they are part of the nominal hazard zone.
- Use Beam blocks, which absorb the beam area diffusely reflecting and composed of fire-resistant materials, to stop unwanted beams.
5. Techniques for Safe Laser Alignment Procedures
The most likely time for laser accidents to occur is during beam alignment. ONLY trained personnel should perform a beam alignment. The ANSI Z136.1 standard suggests the following techniques to prevent accident during laser beam alignment:
- Exclude unnecessary personnel from the laser-controlled areas during alignment.
- Perform alignment at the lowest possible power level.
- When possible, use low-power visible lasers for path simulation of high-power visible or invisible lasers.
- Wear laser protective eyewear and protective clothing as required based on MPE.
- Use beam display devices (image converter viewers phosphor cards, or liquid crystal paper) to locate beams when aligning invisible lasers.
- When inserting any alignment device in the beam, angle the device so that any reflections are directed away from you.Use appropriately rated laser shutters or beam blocks to block high-power beams at their source except when needed during the alignment process.
- Use a laser-rated beam block to terminate high power beams down range of the optics being aligned.
- Use appropriately rated laser beam block and / or laser protective barriers in conditions where alignment beams could stray into areas with uninvolved personnel.
6) Non-Beam Hazards
In addition to the hazards of the laser beam, other hazards associated with the operation of the laser can be present in the lab. Some of the non-beam hazards and possible sources are listed below.
a) Noise
The primary source of noise around laser activities is from capacitator bank discharges. This noise hazard originates from electrical components such as high capacitance condensers producing impulse noises which exceed 140 dBA (the exposure limit for impulse noises). Hearing protection should be required for all individuals who may be exposes to these exceedingly high noise levels.
b) X-Rays
Whenever potentials in excess of 15kV exist in a vacuum, the production and propagation of x-radiation outside the containment must be considered possible. Most laser system use voltages less than 8kV, and typically the higher voltages are on low current devices such as Q-switches. However, some research models are now operating at voltages in the neighborhood above 20kV. If there is any doubt in your mind as the existence of an X-radiation hazard associated with your operation, contact the campus Radiation safety officer.
c) Fire Protection
Some firefighting equipment should be provided; however, the purpose of such equipment should be understood. It is to be used to extinguish or control small fires only. If a fire starts, contact the campus police at 229-9911 or 911 as soon as possible and notify others to leave the area immediately.
d) Electrical Hazards
To date, more than a dozen electrocutions of individuals from laser-related accident have been reported in the United States. In 1986, a graduate student working with a CO2 laser was wiping condensate from the laser tube when he received a 17kV electrical shock. He suffered cardiac arrest and 2nd degree burns. In 1988, a laser repair technician was fatally electrocuted while working alone on a CO2 laser. He defeated the interlock system. A senior research scientist, working alone, was electrocuted while trying to replace a high-voltage regulator tube in a laser power supply. These accidents could all have been prevented.
e) General Hazard Prevention Guidelines:
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- Use the buddy system, especially after normal working hours or in isolated areas.
- Do not engage in any hazardous activities when fatigued or under medication (except under physician’s approval).
- Do not engage in any hazardous activity when your mental attitude, whether through emotional or chemical stimulus, would incline you toward risk taking.
- Specific guidelines to prevent electrical shock:
- Avoid wearing rings, metallic watchbands, and other metallic objects.
- When possible, use only one hand in working on a circuit or control device.
- Never handle electrical equipment when hands, feet or body are wet, perspiring, or when standing on a wet floor.
- With high voltages, regard all floors as conductive and grounded unless covered with a well-maintained, dry rubber matting of a type suitable for electrical work.
- Learn rescue procedures for helping victims of apparent electrocution: Kill the circuit; remove the victim with a non-conductor if still in contact with an energized circuit; initiate mouth-to mouth respiration immediately and continue until relieved by emergency medical staff: have someone call for emergency aid.
- Watch how cords and cables are used and where they cross human traffic in the lab area.
- Use direct plug access as much as possible and do not use extension cords for powering the equipment. If power strips are use, be cognizant of the power draw expected and do not daisy chain the power strips.
f) Airborne Contaminants
Laser Generated Air Contaminants (LGAC) may be produced within certain Class 3B, and Class 4 beams interact with matter. While it is difficult to predict what LGAC may be released in any given situation, it is known that contaminants, including new compounds, can be produced with many types of lasers. When the target irradiance reaches a given threshold, approximately 107 Wcm-2, target materials may liberate toxic and noxious airborne contaminants.
This material is provided as an overview of basic laser safety issues. If you would like additional information regarding lasers or the use of lasers in your lab, please contact the Laser Safety Program at University Safety and Assurances 414-229-6339
g) Ergonomic Hazards
Be aware of how the workstation is laid out and designed when used. Housekeeping is important as is organizing the work area to prevent unwanted human interaction with trailing cables and pipes, sharps, moving robotic arms, and high-pressure water-cooling lines.
7) Laser Protective Eyewear
An enclosure of the laser beam path or laser equipment is the preferred method of control. However, when complete enclosure is not feasible, and other controls are inadequate to eliminate potential exposure, laser-protective eyewear should be used
The purpose of laser-protective eyewear is to attenuate any laser radiation reaching one’s eye to a level below which it will cause injury.
The PI must ensure that the appropriate eyewear is available for use and worn in the laser lab where Class 3B and Class 4 laser are present and there is a potential exposure to the beam or reflected beams at levels above the MPE.
The laser protective eyewear should be selected based on the level of protection required to protect the eyes from a worst -case scenario.
All laser safety eyewear shall be clearly labeled with the optical density and the wavelength(s) for which protection is afforded. Additional labeling may be added for identification purpose in labs with multiple lasers.
Consider following factors for selection appropriate eyewear.
- Factors in selecting appropriate eyewear
- Laser wavelength
- Laser power and / or pulse energy
- Mode of Operation (continuous wave or pulsed)
- Maximum exposure duration (assume worst case)
- Maximum permissible exposure (MPE)
- Maximum Radiant exposure (J/cm2) or irradiance (W/cm2) for which the protection is required.
- Optical density (OD0 requirement of eyewear filters at the specific laser output wavelengths.
- For ultra-fast lasers, non-uniform bleaching may cause degradation of the rated OD of laser eyewear. Check with the manufacturer of the eyewear for the testing results to determine if the eyewear will provide the adequate protection before using them.
- ALSO CONSIDER
- Visible light transmission
- Anti-fogging design or coatings
- Comfort and fit
- Impact resistance
- Side shields protection
- Prescription glasses
- Periodic Cleaning and inspection shall be performed on the eyewear to ensure the eyewear are maintained in satisfactory condition. Use care when cleaning them and follow manufacturer instruction to avoid damage to the absorbing and reflecting surfaces. Check the laser eyewear for:
- Pitting, crazing, cracking, discoloration of the attenuation material.
- Mechanical integrity of the frame
- Light leaks and coating damage.
8) Annual Lab Inspections
Annual lab inspection of the laser labs will be conducted to ensure compliance with the ANSI Z136.1 Standard.
9) Laser Related Injury Reports
In the event of a suspected laser related injury
- Notify you supervisor/ PI immediately
- Fill out the required injury reporting forms (Available on the US&A website) and submit as directed. US&A will be notified when the report is filed.
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- Seek medical help from your own insurance supported provider
- USA will investigate any suspected exposure and complete an incident report
10) References:
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- ANSI Z136.1-2014, American National Standard for Safe Use of Lasers
- Laser Classification Explained http://ehs.lbl.gov/resource/documents/ratiation-protetion/laser/lase-classification-explanation/
- com https://www.laserpointersafety.com/laserclasses.html
- Laser Institute of America, Laser Safety Guide, 10th ed., Laser Institute of America.
- OSHA Technical Manual, available at: https://www.osha.gov/dts/osta/otm/otm_iii/otm_iii_6.html
- University of Wisconsin – Madison, Laser Safety Handbook for Academic and Research Laboratories, March 2021.
11) Glossary:
Authorized Personnel – Individuals approved by management to operate, maintain, service, or install laser equipment.
Continuous wave (CW) Laser– A laser operating with a continuous output for a period ≥ 0.25 s
Controlled area (laser) – An area where the occupancy and activity of those within is subjected to control and supervision for the purpose of protection from laser radiation hazard.
Embedded laser – An enclosed laser that has a higher classification than the laser system in which it is incorporated, where the system’s lower classification is appropriate due to the engineering features limiting accessible emission.
Laser Energy – Total work done by the light, usually measured in joules (i.e., watts * seconds).
Laser Power – Energy per unit time, usually measured in watts (joules per second).
Laser Safety Officer (LSO) – An individual designated by management who has authority and responsibility to manage the overall laser safety program.
Maximum Permissible Exposure (MPE) – The level of laser radiation to which an unprotected person may be exposed without adverse biological changes in the eye or skin.
Maximum Radiant Exposure – Is the radiant energy received by a surface per unit area
Maximum Radiant Energy – Energy of electromagnetic and gravitational radiation. This radiation may be visible and invisible to the human eye.
Nominal Hazard Zone (NHZ) – The space within which the level of the direct, reflected, or scattered radiation may exceed the applicable MPE. Exposure levels beyond the boundary of the NHZ are below the appropriate MPE.
Nominal Ocular Hazard Distance (NOHD) – The distance along the axis of the unobstructed beam from a laser, fiber end, or connector to the human eye beyond which the laser exposure is not expected to exceed the applicable MPE.
Optical Density (OD) – The logarithm to the base ten of the reciprocal of the transmittance at a particular wavelength: Dλ = log10 (1/τλ) – where τλ is the transmittance at the wavelength of interest. Symbol: D (λ), Dλ or OD.
Protective Housing – An enclosure that surrounds the laser or laser system and prevents access to laser radiation above the applicable MPE.
Pulsed laser – A laser that delivers its energy in the form of a single pulse or a train of pulses. In this standard, the duration of a pulse is less than 0.25 s.
Standard Operating Procedure (SOP) – Formal written description of the safety and administrative procedures to be followed in performing a specific task.
Uncontrolled Area – An area where the occupancy and activity of those within is not subject to control and supervision for the purpose of protection from radiation hazards.
Visible Light Transmission (VLT) – The percentage of visible light transmitted through a lens, filter, or other optical element.
Wavelength – The distance in the line of advance of a sinusoidal wave from any one point to the next point of corresponding phase (e.g., the distance from one peak to the next).
LASER Standard Operating Procedure
LASER Standard Operating Procedure (fill-able Word document format)
Alignment Procedures for Class 3b and Class 4 Lasers
- Exclude unnecessary personnel from the laser area during alignment.
- Whenever possible, use low-power visible lasers for path simulation of higher-power visible or invisible laser.
- Wear laser protective eyewear during alignment. Use special alignment eyewear when circumstances (e.g. wavelength, power, etc.) permit their use.
- When aligning invisible (e.g. UV, IR) beams, use beam display devices such as image converter viewers or phospor cards to locate beams.
- Perform alignment tasks using high-power lasers at the lowest power level.
- Use a shutter or beam block to block high-power beams at their source except when actually needed during the alignment process.
- Use a laser-rated beam block to terminate high-power beams downstream of the optics being aligned.
- Use beam blocks or laser protective barriers in conditions where alignment beams could stray into areas with uninvolved personnel.
- Place beam blocks behind optics (e.g.: turning mirrors) to terminate beams that might miss mirrors during alignment.
- Locate and block all stray reflections before proceeding to the next optical component or section.
- Be sure all beams and reflections are properly terminated before high-power operation.
- Post appropriate area warning signs during alignment procedures where laser are normally Class 1 (enclosed).
- Alignments should be done only by those individuals who have received laser safety training.
Eyewash and Safety Shower Information
The American National Standards Institute (ANSI) has established a voluntary standard covering emergency eye wash and shower equipment. This standard ANSI Z358.1 “Emergency Eye Wash and Shower Equipment” is intended to serve as a guideline for the proper design, performance, installation, use and maintenance of emergency equipment. ANSI Z358.1 was originally adopted in 1981 and been periodically revised. Some of the provision of the ANSI Z358.1-1998 standard regarding laboratory eye-washes include:
- The area surrounding the eyewash (3 ft) must be kept clear for easy access during an emergency.
- The valve actuator must be large enough to be easily located and operated by the user.
- The “hands-free” stay-open valve must activate in one second or less.
- The eyewash should be located within 10 seconds of the hazard and the path of the eyewash must be unobstructed.
- The eyewash should be identified with a highly visible sign and the area around the eyewash should be well-lighted.
- The eyewash unit must be capable of delivering 0.4 gallons (1.5 liters) of water per minute for 15 minutes.
- All employees who might be exposed to a chemical splash need to be trained in the use of the equipment.
- The water delivered by the eyewash should be tepid.
- The eyewash should be connected to an uninterruptible water supply with at least 30 PSI flow pressure.
- Plumbed emergency equipment shall be activated weekly to verify proper operation and should be inspected annually.
It is recommended that records be kept of all inspections and maintenance and that the equipment be inspected and maintained in accordance with ANSI Z358.1-1998 and the manufacturer’s recommendations.
Faucet-mounted Emergency Eyewash Units
Many laboratories can use additional eyewash facilities. Eyewash provisions are required wherever corrosive materials or other chemicals “injurious to the eyes” are used (Source: ILHR 32).
If you are considering the installation of an eyewash unit consider the following advantages and disadvantages of the faucet-mounted models (available through most scientific supply and safety supply catalogs). These models are recommended in areas already served by a conventional eyewash installation, but where additional eyewash capabilities are desired.
Advantages
- They are relatively inexpensive ($50-$70 to buy, $0-100 to install, depending on whether you need installation help) versus traditional plumbed-in eyewash installations.
- They are simple to use.
- They are easy to find (we are often surprised that people don’t know where the nearest eyewash is located. However, most lab personnel have no trouble identifying the nearest faucet).
- You have the ability to temper the water (we have tried to “practice” washing our eyes out as recommended for 15 minutes in cold water. Our most machismo soldier-of-fortune type lasted the longest, 60 seconds.) When someone actually has something in their eye, they are probably more motivated to wash their eyes out longer, or they may be more sensitive to the extreme temperature. A training film available from our department (provided by the U.S. Geological Survey) shows how to assist someone washing their eyes out by helping them hold their head in the water flow to overcome the natural tendency to pull away from the cold water.
- You have the ability to flush the system. We recommend that all eyewash systems (fixed and portable) be flushed for three minutes each week to eliminate dangerous bacterial and amoebic growth. We have noted that many eyewashes do not get flushed routinely (NOTE: This is a LAB responsibility! While Facility Services provides routine quarterly to semi-annual testing of emergency showers and eyewashes it is up to each lab to flush their eyewashes for hygiene purposes.) Faucet-mounted eyewashes get flushed out every time someone uses the faucet. Also, they are easier to flush out, because a drain is usually present.
Disadvantages
- Some faucets do not have enough water pressure to provide an adequate stream height out of a faucet mounted eyewash.
- Training of all faucet users is necessary. You don’t want someone to frantically turn on the eyewash and start flushing their eyes after someone else has just used the faucet for hot water. We advise those with faucet eyewashes to flush hot water out with a little cold water after each use.
- Compatibility. Only a few faucet-mount eyewashes are available. Not all faucets will accept these mounts.
- Distance between eyewash spouts. For the least expensive faucet-mount models available, the two water spouts are too close together. Washing both eyes at the same time with these models is difficult, if not impossible.
Summary
Consider the above advantages and disadvantages in installing a faucet eyewash. Overall, review your laboratory operations and determine if additional eyewash protection is warranted. The faucet mounted eyewash will serve well, especially if there is a permanent, plumbed-in unit in the corridor that you can move to once the immediate need for washing a chemical out of your eye is satisfied.
If you would like further information or would care to discuss the use of faucet-mounted eyewashes, e-mail questions to Zack Steuerwald, Lab Safety Program Manager, at x5808.
Vacuum Systems
Many laboratories at UWM require the use of vacuum systems. Several buildings have centralized vacuum systems for laboratories (e.g., Chemistry, Lapham, Enderis). Laboratories may also use other dedicated vacuum equipment. Vacuum may be used for:
- evacuating glass vessels, Dewar flasks, desiccators, cold traps and other chambers
- separation procedures involving distillation and extraction
Your building’s central vacuum system is not intended and must not be used to eliminate chemical wastes. Using the system for chemical waste disposal is in violation of good environmental stewardship and applicable regulations. Improper use of the system will result in reduced service life of the system and increased maintenance costs for your department.
Prior to set up and operation, you need to perform a risk assessment regarding potential hazards.
Vacuum work can result in an implosion, creating the hazard of flying glass and spilled chemicals. Systems at reduced pressure, which are subject to rapid pressure changes, may result in the possibility of liquids being pushed into unwanted locations.
Water-sealed or carbon rotary vane pumps can generate significant heat and friction. Therefore, when pulling a vacuum on a system that generates flammable vapors, care must be taken to ensure hazardous concentrations are not generated in the system.
Please consult with your instructor, supervisor or safety committee for additional safe lab practices involving vacuum systems. Please be sure to document these procedures in your chemical hygiene plan. You need to consider:
- How will you prevent liquids and corrosive gases from being drawn into other laboratory components or the building’s central vacuum system? Traps (Kjeldahl) and condensers should be used to insure these chemicals do not enter the vacuum system.
- Whether relief valves are necesssary for your vacuum work?
- What methods are necessary to protect vacuum pumps?
- What maintenance schedules are necessary, including changing the vacuum pump oil? Pump oil needs to be disposed as a chemical waste.
- How to properly vent the vacuum pump exhaust in a safe and environmentally acceptable way? In most cases, vacuum procedures shall be performed in a fume hood.
Other laboratory safety considerations involving vacuum systems may include:
- What glassware is suitable for vacuum work, and how do you inspect this glassware?
- What methods will you use to protect from implosion? Vessels and other glassware shall be wrapped to reduce fragmentation upon implosion.
- What methods and safe work practices will you use to perform distillations that involve flammable or toxic materials?
- How will you instruct and monitor your lab personnel on safe and proper procedures for work involving vacuum systems?
Gas Cylinder Safety
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Background Information
This document contains basic guidelines and rules to help ensure the safe handling and storage of compressed gas cylinders. Compressed gases are used in a variety of UWM programs such as instructional and research laboratories, health sciences, fine arts, scientific diving, and welding. Compressed gases serve the university in many ways, but gases under high pressure also present a number of hazards.
Mishandled cylinders may rupture violently, release their hazardous contents or become dangerous projectiles. If a neck of a pressurized cylinder should be accidentally broken off, the energy released would be sufficient to propel the cylinder to over three-quarters of a mile in height. A standard 250 cubic foot cylinder pressurized to 2,500 PSIG can become a rocket attaining a speed of over 30 miles per hour in a fraction of a second after venting from the broken cylinder connection.
- Select the least hazardous gases that will work.
- Purchase only the necessary quantities.
- Select gases with returnable containers.
- When receiving gas cylinders:
- Check for leaks
- Visually inspect the cylinder for damage
- Ensure the valve cover and shipping cap is on
- Check for proper labeling
- If a cylinder is damaged, in poor condition, leaking, or the contents are unknown, contact your cylinder vendor. Have the vendor return the damaged cylinder to the manufacturer.
- Wear appropriate foot protection when engaged in moving or transporting cylinders:
- Sturdy shoes are a minimum.
- Steel-toed shoes if required by your supervisor, instructor or department.
- Proper personal protective clothing and equipment shall be worn.
- Always have an appropriate Material Safety Data Sheet (MSDS) available and be familiar with the health, flammability and reactivity hazards for the particular gas.
Cylinder Markings:
| Cylinders must be properly labeled, including the gas identity and appropriate hazards (e.g., health, flammability, reactivity).
Cylinders have several stamped markings. The top mark is either a DOT or an International Code Council (ICC) marking indicating pertinent regulations for that cylinder. The second mark is the serial number. Under the serial number is the symbol of the manufacturer, user or purchaser. Of the remaining marks the numbers represent the date of manufacture, and retest date (month and year). A (+) sign indicates the cylinder may be 10% overcharged, and a star indicates a ten-year test interval. |
- Cylinders should be stored in compatible groups:
- Flammables from oxidizers
- Corrosives from flammables
- Full cylinders from empties
- Empty cylinders should be clearly marked and stored as carefully as those that are full because residual gas may be present.
- All cylinders from corrosive vapors.
- Store cylinders in an upright position.
- Keep oxygen cylinders a minimum of twenty feet from flammable gas cylinders or combustible materials. If this can not be done, separation by a non-combustible barrier at least 5 feet high having a fire-rating of at least one-half hour is required.
- Compressed gas cylinders should be secured firmly at all times. A clamp and belt or chain, securing the cylinder between “waist” and “shoulder” to a wall, are generally suitable for this purpose.
- Cylinders should be individually secured; using a single restraint strap around a number of cylinders is often not effective.
- Keep valve protective caps in place when the cylinder is not in use.
- Mark empty cylinders EMPTY or MT.
- Keep valves closed on empty cylinders.
- Cylinders must be kept away from sources of heat.
- Cylinders must be kept away from electrical wiring where the cylinder could become part of the circuit.
- Store cylinders in well-ventilated areas designated and marked only for cylinders.
- Use a cylinder cart and secure cylinders with a chain.
- Don’t use the protective valve caps for moving or lifting cylinders.
- Don’t drop a cylinder, or permit them to strike each other violently or be handled roughly.
- Unless cylinders are secured on a special cart, regulators shall be removed, valves closed and protective valve caps in place before cylinders are moved.
| Be sure all connections are tight. Use soapy water to locate leaks.
Keep cylinders valves, regulators, couplings, hose and apparatus clean and free of oil and grease. Keep cylinders away from open flames and sources of heat. Safety devices and valves shall not be tampered with, nor repairs attempted. Use flashback arrestors and reverse-flow check valves to prevent flashback when using oxy-fuel systems. Regulators shall be removed when moving cylinders, when work is completed, and when cylinders are empty. Cylinders shall be used and stored in an upright position. |
 Video: Leak Test(187.7Kbps) |
| The cylinder valve should always be opened slowly. Always stand away from the face and back of the gauge when opening the cylinder valve.
When a special wrench is required to open a cylinder or manifold valve, the wrench shall be left in place on the valve stem when in use; this precaution is taken so the gas supply can be shut off quickly in case of an emergency; and that nothing shall be placed on top of a cylinder that may damage the safety device or interfere with the quick closing of the valve. Fire extinguishing equipment should be readily available when combustible materials can be exposed to welding or cutting operations using compressed cylinder gases. |
 Video: opening valve(187.7Kbps) |
- Never roll a cylinder to move it.
- Never carry a cylinder by the valve.
- Never leave an open cylinder unattended.
- Never leave a cylinder unsecured.
- Never force improper attachments on to the wrong cylinder.
- Never grease or oil the regulator, valve, or fittings of an oxygen cylinder.
- Never refill a cylinder.
- Never use a flame to locate gas leaks.
- Never attempt to mix gases in a cylinder.
- Never discard pressurized cylinders in the normal trash.
Poison gases represent a significant hazard. Special precautions not otherwise necessary become prudent when using poison gases.
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- Emergency procedures should be made clear to all involved, including personnel from adjacent labs and building managers.
- Poison gas use after normal working hours requires the approval of the Chemical Hygiene Officer for your department.
- Fume hoods and other ventilation need to be tested before use and checked frequently during the project involving poison gas.
- Notify the Department of University Safety & Assurances before your first use of the poison gas.
- The University Police should also be informed about the locations and types of poison gas in use.
- Document these procedures in your lab’s chemical hygiene plan. As with all chemicals, obtain and review the Material Safety Data Sheet (MSDS) for the poison gas. Maintain an extra copy of the MSDS in your department’s chemical hygiene plan.
Disposal of poison gas cylinders can often cause problems. If the cylinder can not be returned to the manufacturer, UWM can face large disposal costs ($1,000 per cylinder, or more). Even cylinders that can be returned must be shipped on a vehicle which cannot simultaneously carry any other hazardous materials or foodstuffs.
Authority and Reference:
- OSHA 29 CFR 1910.101 and .252 (General Requirements)
- OSHA 29 CFR 1910.102 (acetylene)
- OSHA 29 CFR 1910.103 (hydrogen)
- OSHA 29 CFR 1910.104 (oxygen)
- OSHA 29 CFR 1910.105 (nitrous oxide)
- DCOM 32.15 and 32.28
- Compressed Gas Association (safety publications)
Additional Information:
- Compressed Gas Cylinder Training Outline, UWM Department of University Safety and Assurances
- Safety Alert: Defective Gas Cylinder Valves United Auto Workers Occupational Health and Safety Newsletter, November, 2000