Compressed Gas: Storage & Handling

UC San Diego researchers working with compressed gases must follow an approved Hazard Control Plan (HCP) in the HCP application. This HCP must be preapproved by the principal investigator prior to beginning any work with this material.

Information on this Blink page is supplementary and is not intended to replace the approved HCP.

Follow the requirements for storing CG cylinders:

• Select a cool, dry, and well-ventilated area.
  • Cool areas minimize pressure increases that can result from heat or direct sunlight.
  • Dryness deters rust and corrosion.
  • Ventilation is essential in case of leaks.
  • Never store compressed gas cylinders (with the exception of compressed air) in environmental rooms (i.e., refrigerated cold rooms or warm rooms). These rooms are not well-ventilated and could pose a serious safety concern should a cylinder fail.
• Do not store cylinders next to doors or in corridors where they could possibly obstruct emergency exits from the building.
• Separate oxidizers or other non-compatibles (e.g., oxygen) from flammables by at least 20 feet, or by a non-combustible wall.
• Properly label the cylinders and the storage area. Cylinders need to be identified as full, in-use or empty.
• Arrange storage facilities to permit inventory rotation, using cylinders in order as received from the supplier.
• Store full and empty cylinders separately to avoid confusion. Serious suck-back can occur when an empty cylinder is attached to a pressurized system.
• Designate an area to store empty cylinders for return to the supplier. An area on or adjacent to your building's loading dock is suitable.
• For guidance on how to return empty cylinders, contact STORE. 

Keep inventories lean:

Compressed gas cylinders are typically rented or leased, rather than purchased. Some vendors charge a reconditioning fee on each cylinder that is not returned within 2 years. This fee may be significant in relation to the actual cost of the gas.

• Review your cylinder inventory monthly.
• Return empty and unwanted cylinders to the vendor to eliminate potential hazards, save on cylinder rental bills, and avoid possible reconditioning fees.
• Do not keep non-corrosive gases longer than 10 years from the last hydrostatic test date (usually stamped just below the neck of the cylinder) unless otherwise regulated.
• Never store corrosives longer than 6 months (examples: ammonia, hydrogen chloride, chlorine, and methylamine). Cylinders containing corrosives degrade over time.
• Return all cylinders that appear unsafe or show signs of corrosion, dents, dings, pitting, bulging, etc. Contact STORE for removal. 

Compressed gas cylinders in UC San Diego facilities must be secured at all times, whether empty or full.

During the 1994 Northridge earthquake, gas cylinders that had been double-chained and bolted to a secure surface stayed in place. Single-chain restraints were not as successful. C-clamps did not work at all.

Store cylinders upright and secure them to a substantial, fixed surface with upper and lower restraints made of non-combustible material, preferably chain and Unistrut®. (See the image at right for an example of properly secured cylinders.)

How to effectively restrain cylinders:

• Restraints should be tight.
• Position the upper restraint no less than 1 foot from the shoulder of the cylinder. Position the lower restraint no less than 1 foot from the floor.
• C-clamps or bench mounting brackets are not allowed!
• Preferably restrain cylinders individually. If unavoidable, only restrain 3 or fewer cylinders per restraint. When restraining multiple cylinders keep them secure and interlocked into a compact group with the sides and bottoms of all cylinders fully contained.
• Cap cylinders when not in use.

Read the Safety Data Sheet and label information before starting work with a new material.

Follow these operational requirements:

• Label both the cylinder and gas line with the name of the gas. Do not depend on color codes.
• Work in a well-ventilated area when using compressed gases.
• Use the correct regulator. Ensure each gas in use has its own dedicated regulator. Never use adapters.
• Never permit a flame or spark to come in contact with any part of a compressed gas cylinder.
  • Install flashback protectors on cylinders of flammable gases, such as oxy-acetylene torch units.
• Use a trap or suitable check valve when discharging gas into a liquid to prevent liquid from getting back into the cylinder or regulator.

In case of cylinder leaks that cannot be stopped by tightening the valve gland or packing nut, do the following:

• For hazardous gases:
  • Leave the room, closing the door behind you.
  • Secure the room to prevent entry.
  • Sound the fire alarm.
  • Call for emergency assistance:
    • UCSD Police
      Dial 9-1-1, or (858) 534-4357 from a cell phone. Tell the dispatcher the name of the gas.
    • UCSD Medical Center
      Dial 6-1-1-1, or (619) 543-6222 from a cell phone. Tell the dispatcher the name of the gas.

• For non-hazardous gases:
  • Close the leaking valve. Is it still leaking?
    • Yes – Replace the cylinder cap and notify Environment, Health & Safety (EH&S) at (858) 534-3660.
    • No – Contact STORE for removal at (858) 534-7467.

Follow these best practices for transporting CG cylinders:

• Leave the valve protection cap on until the cylinder is secured against a wall or bench or placed in a cylinder stand, and is ready for use.
• Use a hand truck or other suitable device to transport cylinders, even for short distances. Secure the cylinder to the hand truck with a chain or strap.
  • Do not roll, drag, or slide containers.
  • Do not lift cylinders by cylinder caps.
• Before returning empty cylinders to the supplier:
  • Close the valve. Leave some positive pressure in the cylinder.
  • Replace original valve outlets and protective caps shipped with the cylinder.
  • Mark or label the cylinder "empty" and store it in a designated area for the supplier.
• Important: Move unattended cylinders to a secure location as soon as possible.

In addition to standard storage and operational requirements listed above, employ special precautions for cylinders containing flammable, oxidizing, or corrosive gases (empty or full). See the Toxic and Hazardous Gas Classifications Chart for detailed information on all gases.

Flammable gases

• Storage:
  
  • Separate from cylinders containing oxidizing gases by a minimum distance of 20 feet or by a noncombustible partition extending not less than 18 inches above and to the sides of the stored material.
  • Flammable gases can be stored/used in the open lab if they are stored/used appropriately. If they are stored/used in an approved gas cabinet, the gas cabinet must be equipped with fire sprinklers.
  • Never store flammable gases near ignition or heat sources, electrical panels, unprotected electrical connections, or in corridors.
  • Keep quantities to a minimum. There are strict quantity limits as determined by Fire Code.
  • There may be circumstances where using a pure flammable gas may pose unacceptable risks. It may be necessary to purchase a reduced concentration mixture (e.g., 1% hydrogen and 99% argon).
    • If you need large volumes (more than 1 large cylinder), contact the EH&S Chemical Hygiene Officer.
• Operations:
  • Use flow restrictors to prevent a sudden large unexpected release.
  • Detection systems may be required. Contact the Chemical Hygiene Officer for a review. 
• Inert/Flammable Gas Mixtures
  • Nitrogen/Hydrogen – Any mixture greater than 5% hydrogen balance nitrogen is flammable.
  • Argon/Hydrogen – Any mixture greater than 3% hydrogen balance argon is flammable.
• Additional information on hydrogen use:
  • Always use Stainless Steel (SS) tubing to convey hydrogen gas. 
  • Prevent hydrogen leaks by carefully connecting gas regulator and tubing.
  • Keep vigilant for leaks.
  • Can only be used in spaces with adequate ventilation.
  • Eliminate likely ignition sources
  • Always assume hydrogen is present, and verify the system has been purged to less than 1 percent when performing system maintenance on a hydrogen system. Inert gases such as Nitrogen & Argon can be used for purging.
  • Anaerobic chambers:
    • Always assume oxygen is present, and verify the system has been purged to the appropriate level when reintroducing hydrogen into a system.
    • Oxygen and hydrogen sensors are required at all times. No exceptions.

Oxidizing gases

• See Oxygen System Safety (PDF) for more detailed information on oxygen system hazards and safety.
• Storage:
  • Do not permit oil or grease to come in contact with compressed oxidizing gases — explosions may occur!
  • Separate oxidizers from cylinders containing flammable gases by a minimum distance of 20 feet or by a noncombustible partition extending not less than 18 inches above and to the sides of the stored material.
  • Never store oxidizers near flammable solvents, combustible materials, unprotected electrical connections, or ignition or heat sources.
    • Note: Fire code piping requirements may apply in your facility. Consult the EH&S Chemical Hygiene Officer.
• Operations:
  • Diligently clean regulators and tubing used with oxidizing gases to remove oil and other reducing agents.
• Piping
  • Oxygen systems must be plumbed with steel, brass, copper or stainless steel (as per National Fire Protection Association regulations).  
  • Plumbing must be installed by Facilities Management.
  • Must be approved by the Chemical Hygiene Officer.

Corrosive gases

• Storage:
  • Never store corrosives longer than 6 months (examples: ammonia, hydrogen chloride, chlorine, and methylamine). Cylinders containing corrosives degrade over time.
• Operations:
  • Inspect cylinder valves periodically for corrosion.
  • If a cylinder or valve is noticeably corroded, contact the gas vendor and follow their instructions.
  • Alert the vendor to any damage that might impair the integrity of the cylinder before the cylinder is returned.
  • Use caution if flow does not immediately start when a valve is opened slightly — there could be a plug in the valve.

Additional precautions are required for toxic and hazardous gases (classes I, II, and III).

• See the Toxic and Hazardous Gas Classifications Chart to identify the hazard class of a particular gas.
• See Hazard Class Requirements Matrix for detailed information on requirements and exemptions.
• Handle toxic, flammable, and corrosive gases in a fume hood.
• Use only small cylinders of toxic gases whenever possible. Requirements are relaxed for small quantities and short-term usage.
• See the "Flammable, oxidizing, and corrosive gases" section above for special precautions.

Caution: Avoid using lecture bottles whenever possible. Lecture bottles have universal threads and valves, and some of them are interchangeable. This increases the risk of accidentally mixing incompatible materials.

Helium is a colorless and odorless compressed gas. It is non-toxic and non-flammable.

If you use helium to fill balloons for parties or social events, be aware that careless handling of the cylinders or improper use of helium could cause an accident with serious results.

Follow these guidelines for safely using helium to fill balloons:

• Follow all compressed gas guidelines described on this page. The same hazards and methods for safely transporting, storing, and working with industrial CG cylinders apply to helium cylinders used to fill balloons.
• Always use the proper equipment designed for balloon-filling operations. Order your helium and balloon valve/inflator from Logistics STORE for next-day delivery.
• Follow these guidelines for balloon-filling operations:
  • Fill balloons in well-ventilated areas to prevent the risk of asphyxiation.
  • Check all connections for leaks prior to use.
  • Place balloons firmly onto the rubber nozzle and tilt. The further the nozzle is tilted, the higher the pressure that will be released.
  • Make sure the rubber nozzle is not pressing against the inside wall of the balloon neck during inflation. This can blow a hole through the balloon.
  • Close the cylinder at the valve after each use. Helium can leak through the inflator if left on for long periods of time.
  • Never leave the cylinder unattended when it's operational.
  • Never allow anyone to breathe helium from the cylinder. Although helium is not poisonous, it can lead to asphyxiation.
  • Never allow children or unauthorized people to handle balloon-filling equipment.
  • Minimize waste by ensuring gas does not escape when the balloon is being inflated, or when the balloon is removed from the nozzle.
• Transporting the cylinder:
  • Remove the inflator and place the protective cap on before transporting the cylinder to prevent damage.
  • Use a cylinder cart to transport cylinders, even for short distances. Secure the cylinder to the cart so it can't tip, fall over, or bang into another cylinder.
  • Do not roll, drag, or slide cylinders.
  • Do not lift cylinders by cylinder caps.
• Storing the cylinder:
  • Remove the inflator and place the protective cap on the cylinder when storing.
  • Store the cylinder upright and secure it to a substantial, fixed surface with upper and lower restraints made of non-combustible material, preferably chain and Unistrut®. (See the image below for an example of properly secured cylinders.)
  • Make sure cylinders are not placed where they might form part of an electric circuit.
  • Return empty or unused cylinders promptly to STORE.

Make sure personnel are trained to safely handle and work with compressed gas.

• See CG: Classification and Requirements Overview for 2 "UC San Diego Compressed Gas Training" videos, including handouts presented with the program.