Proper Purging of a Propane Tank

7th Jun 2019

Proper Purging of a Propane Tank is very Important!

DOT Cylinder Purging Procedure:

  • Exhaust to atmosphere any air pressure in the container*
  • Pressurize the cylinder to 15 psig with propane vapor.  Never use liquid propane.
  • Exhaust vapor to atmosphere
  • Repeat four more times

SAFETY WARNING:  The purging procedure should be done by a qualified trained person.  Exhausting propane vapor incorrectly could result in ignition of exhausted propane fumes resulting in burn injury or death!

Why is purging a new propane tank so important?

  • If the natural volume of air inside your tank is not removed prior to the 1st filling, these problems will result:
  • During the warmer months of the year your tank could experience excessive and false container pressures. This could cause the safety relief valve to open, blowing off (discharging) the excessive pressure.
  • Any air mixture in the vapor space of the tank will be carried to the appliance burner. This could result in unwanted service calls from pilot light outage or improper burner flame function.

However, if the atmospheric air inside your new tank is properly purged:

  • The storage tank will fill faster, your appliances will function more consistently, pressure relief valves on your tank will be less likely to discharge.

WARNING!  Never Purge with Liquid Propane!

Purging with liquid propane causes the liquid propane being pumped into your tank to flash into vapor, chilling the container and condensing any moisture vapor on the walls of the tank where it remains while the pressure is being blown down. Additionally, less than 50% or as little as 25% of the air will be removed if the purging is done with liquid propane.