The pressure relief vessel is used for the safe venting and filtering of pig propellant (compressed air, nitrogen etc.) and collection of residual contaminate. The T20 is equipped with a demister that separates contaminates and pig propellant. The volume of the residual contaminate is monitored by a level control switch allowing it to be disposed off as required.

The pressure relief vessel is available with a volume of 60, 100 and 300 litres as well as with or without heating.