Compressed Gas Cylinder Safety
Store, move, secure and use compressed gas cylinders safely.
Table of contents
A compressed gas cylinder holds a great deal of energy in a small steel shell. A full cylinder of oxygen or argon can be around 2,000 pounds per square inch or more. If the valve snaps off, the cylinder can take off like a rocket, through a wall or a person. Gas leaks bring other hazards: fire, explosion, poisoning and suffocation. Cylinders turn up in welding, HVAC, plumbing, labs, hospitals, forklift fuel and drink dispensing, so these rules apply in many trades.
What You Will Be Able to Do
- Read a cylinder label and sort cylinders by hazard.
- Store and secure cylinders, including how far to keep oxygen from fuel gases.
- Move a cylinder by hand, on a cart and in a vehicle.
- Set up a regulator and check for leaks.
- Handle empty and damaged cylinders correctly.
Know What Is in the Cylinder
Read the label, every time. Cylinder color is not a reliable way to identify a gas, because colors vary by supplier. If you cannot read the label, do not use it. Mark it and return it to the supplier.
| Hazard group | Examples | Main danger |
|---|---|---|
| Fuel gases | Acetylene, propane, hydrogen, MAPP-type gases | Fire and explosion |
| Oxidizers | Oxygen, nitrous oxide | Make other things burn fast |
| Inert gases | Nitrogen, argon, helium, carbon dioxide | Displace oxygen and suffocate you |
| Toxic or corrosive gases | Ammonia, chlorine | Poisoning, burns |
| Refrigerants | Many HFC and HFO blends | Displace oxygen in closed rooms, cold burns |
Inert gas is easy to underestimate. Nitrogen and argon have no smell, and in a small or low space they can push out breathable air. You may pass out with little or no warning.
OSHA requires employers to keep cylinders in safe condition, and its rule at 29 CFR 1910.101 points to Compressed Gas Association guidance. Welding gases are covered in 1910.253 and 1926.350. The Safety Data Sheet for each gas lists its specific hazards.
Storing Cylinders
- Keep them upright and secured with a chain, strap or stand so they cannot fall. Use the top half of the cylinder, and secure small groups, not a loose crowd behind one chain.
- Keep valve caps on any cylinder that has a cap and is not in use.
- Keep them in a dry, ventilated place, away from heat, flames, sparks, direct sun, corrosive chemicals and traffic. Cylinder temperature should not go above 125°F.
- Separate full from empty, and label which is which.
- Separate by hazard.
The 20-Foot Rule
Oxygen cylinders in storage must be kept at least 20 feet from fuel-gas cylinders and from combustible materials, especially oil and grease. If they have to be closer, a noncombustible barrier at least 5 feet high with a fire rating of at least one-half hour must stand between them. This does not apply to cylinders on a cart that are set up for use, but a cylinder on a cart that sits unused for a long period counts as storage. Your site may set a time limit.
Warning: Oil and grease can ignite in contact with high-pressure oxygen. Keep oil, grease and oily gloves away from oxygen cylinders, valves and regulators. Never lubricate them.
Moving Cylinders
- Close the valve and take off the regulator, unless it is on a special cart built for that.
- Put the valve cap on.
- Use a cylinder cart, and chain the cylinder to it. For a short move on a flat floor, you may tilt it and roll it on its bottom edge. Do not drag or slide it, and do not roll it on its side.
- Do not lift by the cap, and never lift a cylinder with a magnet or a sling. Use a cradle or a platform made for the job.
- Keep it from falling. Do not drop a cylinder, and do not let cylinders strike each other.
- In a vehicle, keep it upright and secured, with the cap on. Keep the space ventilated. Carrying gas in a closed van or car can build up a dangerous atmosphere. Take it straight to where it is going, and do not leave it in a closed vehicle.
Commercial transport has additional hazardous materials rules. Ask your employer what applies to your load.
Setting Up and Using a Cylinder
- Secure the cylinder upright. Acetylene must always stay upright, because a liquid inside can come out with the gas.
- Check the valve for dirt and damage. If your training and site rules allow, crack the valve briefly to clear dust, standing to the side and pointing it away from people and flames. Do not crack fuel gas near any ignition source.
- Attach the correct regulator. Fittings are made so that the wrong gas cannot connect. Never force a fitting or use an adapter to get around that.
- Back off the regulator's adjusting screw, so no pressure goes to the hose yet.
- Stand to the side, away from the gauge faces, and open the cylinder valve slowly.
- Open oxygen all the way. Open acetylene no more than about one and a half turns, and leave the wrench on the valve so you can close it quickly.
- Set the working pressure.
- Check for leaks with an approved leak-detection solution or a detector. Never use a flame.
Keep a cylinder well away from where sparks or slag will land. Never strike an arc on a cylinder, and never use one as a roller or a work support.
Warning: Never use acetylene above 15 psig. Above that pressure it can become unstable and explode. Watch the regulator, and stay under the limit.
Use flashback arrestors on torch hoses where your procedure calls for them. They stop a flame from traveling back into the hose and the regulator.
Never use oxygen in place of compressed air for tools, blowing off dust or ventilating a space. An oxygen-rich atmosphere makes clothes and hair burn fiercely.
When You Finish
- Close the cylinder valve.
- Release pressure from the hoses and the regulator.
- Back off the adjusting screw.
- Put the valve cap on if the regulator comes off.
- If it is empty, close the valve, mark it "Empty" or "MT," and store it apart. Leave a small amount of pressure in the cylinder, so that air and moisture cannot get inside.
When Something Goes Wrong
| Problem | What to do |
|---|---|
| Hissing or the smell of gas at the valve | Close the valve if you can do that safely. Remove ignition sources, ventilate, and clear the area. Report it |
| A leak that will not stop | Evacuate, and move the cylinder outdoors only if it is safe. Call your emergency number |
| A cylinder is in a fire or very hot | Evacuate and call 911. Do not stay to fight it |
| Damaged valve, dents, bulges or rust | Tag it, do not use it, and call the supplier |
| A label you cannot read | Do not use it. Return it |
Never try to repair a cylinder, or to transfer gas from one to another unless that is your trained job. Only the owner or supplier refills, repairs and tests them.
Common Mistakes
| Mistake | What it costs | Better habit |
|---|---|---|
| Standing a cylinder loose "for a minute" | It falls, and the valve breaks off | Secure it first |
| Moving a cylinder with the regulator on | Regulators break and valves shear | Remove it, unless it is on a proper cart |
| Storing oxygen beside fuel gas | A small leak feeds a big fire | 20 feet or a rated barrier |
| Using color to identify gas | The wrong gas in the wrong system | Read the label |
| Using a cylinder in a closed room with no ventilation | Oxygen is displaced with no warning | Ventilate, and monitor the air |
Check Your Understanding
1. You need to take a 250-pound cylinder down a long hallway. What do you do first?
Close the valve, remove the regulator, put on the cap, and chain the cylinder to a cart.
2. Your oxygen and acetylene cylinders are finished for the week and stand side by side in a storage cage. Is that okay?
No. Unless it is a working cart in use, stored oxygen must be 20 feet from fuel gas, or have a noncombustible barrier 5 feet high with a one-half hour fire rating between them.
3. A coworker wants to blow dust off a bench with the oxygen hose because the air line is far away. What do you say?
Do not. Oxygen soaks into clothing and makes it burn fiercely. Get the air line or use a vacuum.
4. You smell gas at a propane cylinder fitting in a shop. What do you do?
Stop work, kill ignition sources, close the valve if it is safe, ventilate the area, and report it. Check for the leak with a leak-detection solution, never with a flame.
Key Takeaways
- Read the label. Color does not tell you what is inside.
- Keep cylinders upright, secured and capped when not in use.
- Keep stored oxygen 20 feet from fuel gas, or use a 5-foot barrier rated for at least one-half hour.
- Move cylinders on a cart with the regulator off and the cap on.
- Keep oil and grease away from oxygen, and keep acetylene under 15 psig.
- Inert gases can suffocate you with no warning, so ventilate.