Valving of CO2 Cylinders

Catalina Cylinders recommends that anyone valving CO2 cylinders should be aware of the hazards associated with CO2 and be trained in safe practices of valving CO2 cylinders. Catalina Cylinders has compiled the following  list of items that should be included in all safe practices for the valving CO2 cylinders.

Valve Removal

  1. Verify the cylinder is free of  charge and not under pressure before attempting to remove the valve.
  2. Only discharge the remaining charge of a CO2 cylinder in a well ventilated area.
  3. Position the cylinder with outlet port  of the valve facing away from all personnel and/or equipment.
  4. Slightly (“crack”) open the handwheel  of the valve discharging or releasing the residual CO2 charge. Leave the  handwheel of the valve open throughout the valve removal process.
  5. Fitting a wrench snugly to the valve body,  use force turning the wrench counter clockwise to loosen the valve.
  6. If the valve cannot be loosened, stop,  remove the wrench and apply a small amount of penetrating release agent at the  junction of the valve and cylinder and allow time, 5 – 15 minutes, for the release agent to penetrate the junction.
  7. Again attempt to loosen the valve. It may take  some time to work the valve free from the cylinder. If a valve is really stuck  and a release agent is used, you may have to stop periodically in the removal process and  reapply the release agent and allow time for the newly applied release agent to work.

Valve Insertion

  1. Verify that the cylinder was manufactured for CO2 service.
  2. Verify the valve is a CGA recommended CO2 valve.
  3. Verify that the safety device is the  correct safety device, is rated at the test pressure of the cylinder, and has not been actuated or altered (tampered with).
    • Never tamper with the safety device.  If the safety device appears to be tampered with, do not use the valve.
    • Never replace the safety device of a valve on a cylinder that is charged.
    • Catalina Cylinders recommends when  replacing a safety device replace the whole safety device assembly.
    • If a safety device has been actuated  and the cylinder has vented, then the cylinder may have been overfilled or exposed to high heat.
  4. Inspect the inlet and outlet threads of the  valve and the threads and o-ring gland of the cylinder for damage. If either the valve  or cylinder has damage to the threads or the o-ring gland area, do not insert the valve into the cylinder.
  5. Inspect the cylinder threads and the cylinder  internally verifying that the cylinder is free of all contaminants (i.e. release agents,  moisture, soils, corrosion, etc.). Do not proceed if you feel the cylinder  may be contaminated. Reference Catalina Cylinders Technical Support Document,  Cylinder Cleaning, for common methods of cleaning a cylinder.
  6. Catalina Cylinders recommends the  insertion of a new buna-N o-ring, with a hardness of 90 shore, every time the valve  of a cylinder is removed and re-installed. Verify that the new o-ring  is free of all damage. Following are the buna-N o-ring sizes for the different inlet thread sizes of CGA valves.
    Thread Designation Valve Designation Buna-N O-ring Size
    .625 – 18 UNF CGA 323 206
    .750 – 16 UNF CGA 320 210
    1.125 – 12 UNF CGA 320 216
  7. Catalina Cylinders has found it easiest  to place the o-ring on the valve and then insert the valve into the cylinder tightening  the valve hand tight. Placing the o-ring in the o-ring gland of the cylinder and  then inserting the valve is known to have damaged the o-ring in some instances.
  8. Final tightening of the valve should be done  with a calibrated torque wrench to the recommended torque values noted as follows:
    Thread Catalina Cylinders Catalina Cylinders
    Designation Recommended Torque Maximum Torque
    .625 – 18 UNF 40 lbf-ft 50 lbf-ft
    .750 – 16 UNF 40 lbf-ft 50 lbf-ft
    1.125 – 12 UNF 40 lbf-ft 50 lbf-ft
  9. Close the valve with no more than 1 lbf-ft torque.
  10. Posted in: Carbon Dioxide