Prepare for Use
The following guidelines will help prevent incidents related improper use of to compressed gases:
- Order only what you need. Compressed gas cylinders come in many sizes. Order the smallest amount available.
- Download and read the Safety Data Sheet from the manufacturer. Understand the hazards of the gas you will be using. Gases may be flammable, toxic, corrosive, reactive or inert.
- Provide your cell phone number to the gas delivery vendor so they can reach you upon delivery. Compressed gases must be received by lab personnel; they cannot be left in the hallway, unsecured, or unattended.
- Make sure the compressed gas company will take back the gas cylinder when you are done with it. This is especially important when you order specialty gases. It is very costly to the University to dispose of compressed gases through UVMs laboratory waste disposal procedure.
- Choose the appropriate tubing and regulator. Airgas has a lot of information about Regulator Selection, Installation, and Operation.
Watch (or show to your lab group) the Compressed Gas safety video that was made with Airgas.
The Lab Supervisor is responsible for training lab personnel about the hazards of the compressed gases used in the lab. Training should include a review of the Safety Data Sheet, proper handling, storage, leak testing, and use. Have an emergency plan in place in case something goes wrong. If you need additional training, contact Airgas to train your lab group.
Make sure you are using the correct regulator for the particular gas that is inside the cylinder. If the regulator connections do not readily fit together... STOP! This may mean you are using the wrong regulator. Never force connections to fit; forcing can permanently damage the cylinder threads.
Prepare for a Leak or Emergency
Visually inspect compressed gas cylinders during your monthly self-inspection. Check apparatus for proper labels, dents, excessive rust, pitting, bent lines, disconnected lines, or other physical damage.
Regularly use "Snoop," soapy water, or leak detection equipment to check for leaks in the gas transport system. If a leak is detected, immediately call the vendor to arrange for the cylinder to be removed.
Higher-hazard gases may require redundant levels of engineering controls, such as a leak detection system with an alarm.
Never use Teflon tape on CGA fittings (straight thread) where the seal is made by a metal-to-metal contact. Use of Teflon tape causes the threads to spread and weaken, increasing the likelihood of leaks.
Download a compressed gas cylinder safety checklist (PDF).
Labeling and Storage
Do not rely on the color of the cylinder for identification of the gas. Color-coding may be inconsistent from vendor to vender. Make sure the label on the cylinder is clearly visible at all times.
If a cylinder is piped through a wall, label the piping with the specific gas.
Each cylinder should be labeled as "Full," "Part Full," or "Empty." Perforated hang tags are available for this purpose.
Cylinders must be secured to a stable oject (non-movable counter, wall, etc.) and secured with a chain or strap about 2/3 of the way up on the tank. Tighten the strap or chain to prevent the compressed gas tank from accidentally falling over.
Brackets designed for compressed gases should be used to store cylinders properly. Propylene straps and/or weight-rated chains can be used. See the next accordion for additional information regarding securing cylinders.
Store gases by hazard. This means gases with this same hazard class should be stored in the same area.
- Make sure the labels can be seen and hang tags are visible.
- Flammable gases should be kept at least 20 feet away from combustible materials and/or incompatible gases (e.g. oxidizers) or substances. Storage areas that have a non-combustible wall at least 5 ft in height and with a fire resistance rating of at least 30 min may be used to segregate gases of different hazards in close proximity to each other.
- Toxic gases must be stored in a chemical fume hood or in a properly ventilated gas cabinet.
- Inert gases are compatible with all other gases and may be stored together.
- Empty tanks should be labeled as such and stored away from full tanks.
Lecture Bottle Storage
"Lecture bottle" is the term used to describe small hand-held cylinders. Each lecture bottle must be properly secured, stored, and used in an upright position. Never store them laying down in a drawer or cabinet. Toxic and corrosive lecture bottles should be secured and stored inside of a chemical fume hood or a properly ventilating gas cabinet. Stands are available through local compressed gas vendors as well as lab safety suppliers.
Additional Guidelines for Storage
- Store gases according to hazard compatability. Never store flammable gases next to oxidizers.
- Never store compressed gases in exits or egress routes.
- Gases should be used and stored only in well-ventilated areas.
- Never store gases for longer than one year without use.
- Always screw on an appropriate gas cap on cylinders that are not in use.
- Store compressed gases in an upright position. Never lay them on their side in a cabinet.
- Gases should be stored in the order in which they are received and will be used.
Securing Cylinders and Regulator Guidelines
Compressed gas cylinders must be secured to a stable object (counter or wall) and secured with a chain or strap about 2/3 of the way up on the gas cylinder so it cannot fall over.
All cylinders MUST have a cap or a regulator at all times. When not in use or during transport, a cap should be used that is sized to fit the gas tank correctly.
- Be sure to use valves, tubing, and tube fittings that are designed for the application. If in doubt, contact the manufacturer or distributor.
- Clean all threads and mating surfaces of the regulator and hose connections before the regulator is attached with a lint-free cloth. Particulates can clog the regulator filter (if so equipped) or cause the regulator to malfunction.
- Attach the regulator securely, with the secondary valve closed and with the regulator flow backed off before opening the cylinder valve.
- Tighten the regulator nut and tube connections only only with a cylinder wrench or other tightly fitting wrench . When working with tubing or tube fittings, where turning a wrench could put torque on weaker system parts, use a second wrench in a suitable location to counter the torque. Never force it.
- Teflon tape should only be used on tapered pipe threads where the seal is made at the threads. Do not use teflon tape on cylinder connections or tube fitting connections, all of which have metal-to-metal face seals or gasketed seals. NEVER USE TEFLON TAPE ON AN OXYGEN CYLINDER.
- When opening a cylinder valve, open the valve slowly. Point the valve opening away from yourself and other persons. Never use a wrench or hammer to open or close a hand wheel-type cylinder valve. If the valve is frozen and cannot be operated by hand, call and return the cylinder to the gas vendor immediately, and ask for a replacement.
- Before a regulator is removed from a cylinder, be sure to close the cylinder valve and release all pressure from the regulator.
- Never completely empty a rented gas cylinder. Instead, discontinue use of the cylinder when it has at least 25 psi remaining. Hang a Full/Empty tag on it so that others know that it is nearly empty. Verify that the valve is closed. Then, secure with a cylinder cap.
- Utilize pressure relief devices (e.g., pressure relief valves and rupture discs) where appropriate to protect against the overpressurizing of any element of the compressed gas system that cannot safely withstand full cylinder pressure.
- Prohibit oil or grease to contact cylinders or their valves, especially cylinders containing an oxidizing gas (e.g oxygen).
- Where there is any chance for equipment malfunction, inspect the condition of the equipment at appropriate intervals.
Contact the Compressed Gas vendor (on campus daily) to move gas cylinders. Lab personnel may move compressed gas cylinders under the following conditions ONLY:
- They have received and documented that they have adequate training.
- The valve is closed, the regulator has been removed, and the safety cap is securely in place.
- An appropriate cart is used. A cylinder card is required for tanks over 35" in height, another cart or dolly will work for smaller cylinders. The cylinder must be secured on the cart. "Hand rolling" cylinders is not permitted.
- Lab personnel may not move large (>35" in height) cylinders between floors of a building or outside of a building.
Contact the Compressed Gas vendor when you need to move cylinders in any of the following situations:
- Outside of the building,
- When you do not have an apropriate cart,
- When you do not have appropriate safety caps, or
- When you do not have appropriate training.
Compressed Air Safety
Compressed air accidents can result in serious, disabling injuries or even death.
Compressed air hazards include the following:
- Air pressure
- Flying particles
- Trip hazards (from hose)
Air under pressure can puncture and penetrate the skin. If compressed air punctures the skin, it can potentially form an air bubble and get into the bloodstream (embolism); this can be fatal if the bubble reaches the heart or lungs. Compressed air aimed at the ear can be powerful enough to rupture an eardrum. Never joke around with compressed air; it is not a toy.
The pressure at the nozzle of a compressed air gun should be set to no more than 30 psi. Never clean objects, machinery, bench tops, or clothing with compressed air.
Always aim the compressed air gun toward the floor, not at another person. Injuries can be caused by the air jet or by particles thrown into the air and into your eyes or those of a neighbor nearby. For this reason, eye protection must always be worn when using compressed air.
Compressed air can generate noise up to 120 decibels; wear proper hearing protection when using compressed air.
Please review this Compressed Air Safety (PDF).