Faulty Gas Cylinder Regulator Causes Explosion

A chemist was seriously injured in a laboratory when opening the valve on a compressed gas cylinder. The regulator exploded and shattered her jawbone, causing unconsciousness. The Canadian Ministry of Labour and the Technical Safety and Standards Association (TSSA) investigated the accident and found a fault in the regulator. The regulator was about ten years old and may have been retrofitted during that time. The following steps should be taken by all laboratory workers to prevent similar accidents: 
  • Wear appropriate personal protective equipment such as safety glasses or goggles. Make sure the cylinder is tightly secured before removing the valve cap.
  • Use only the regulator designed for the gas being used. If the regulator is not the correct one, the connector will not fit. Do not force connections.
  • Visually check the regulator for evidence of damage or contamination and remove any foreign material before attaching the regulator.
  • If the regulator is dropped, it should be sent to the supplier for servicing.
  • When attaching the regulator do not use Teflon tape. Use a wrench to tighten the connector securely.
  • Keep the cylinder between you and the regulator when opening the cylinder valve. Do not stand in front or behind the pressure gauges when applying pressure to the regulator.
  • Open the regulator's pressure adjusting valve counterclockwise until it feels free. Slowly open the cylinder valve (opening the cylinder valve quickly may cause damage to the regulator valve and seals). When the high pressure gauge indicates maximum pressure, open the cylinder valve fully.
  • Test regulator for leaks. A soapy water solution can be used for argon, nitrogen, hydrogen or air. For other gases consult supplier.
  • When not in use store the regulator in a clean place and do not place anything directly on top of the regulator.

Maintenance of Regulator: 

We recommend that you do an internal check and maintenance on the regulator every six months and that the regulators are sent to the supplier for servicing every two years. Record all tests and maintenance on a Repair Log Form for Regulators. 

Visual Inspection

  • Carefully examine the entire regulator.
  • Check condition of outlet and inlet.
  • Look for worn threads and damage.
  • Check to see if gauges are damaged.

Check for Pressure "Creep"

  • Put regulator onto an appropriate cylinder with at least 1500 psi.
  • Make sure pressure adjusting valve is completely free by turning it counterclockwise.
  • Slowly open the cylinder valve until it is fully open.
  • Set low pressure gauge to approximately 20 psi, then close off the downstream pressure. Record set pressure. Check pressure after 30 minutes and record the pressure.
  • If pressure setting has increased, remove regulator from service and send out for evaluation. 

Functional Test of Regulator

  • Close regulator by turning the pressure-adjusting valve counterclockwise until key is fully released.
  • Close the cylinder valve and drain the downstream line.
  • The low pressure gauge will indicate zero. Record low pressure gauge reading. The high pressure gauge will read full pressure. Record initial high pressure.
  • If the low pressure gauge does not read zero when all pressure is removed, it may be damaged and must be replaced.
  • Check high pressure gauge reading after at least 30 minutes. Record high-pressure reading. Any pressure drop will indicate leakage.
  • Release pressure in regulator by turning pressure adjusting-key clockwise. After venting, fully release pressure-adjusting key by turning it counterclockwise.