The purpose of the Leak Detection / Nitrogen Purge is to confirm that the wash station is sealed and to purge the air from the reactor.
The leak detection step is required to ensure that a leak of oxygen rich air cannot enter the reactor during the caustic wash cycle. The leak detection tests all valves immediately adjacent to the wash bay. Leak detection utilizes a pressure up and hold sequence measuring pressure loss over a period of time. If the pressure loss is greater than that specified in the parameters of the PLC, a failed purge alarm is activated putting the wash bay in pause. The sequence is as follows:
• Pressure Rx to 1.5 PSIG
• Wait 5 minutes for pressure stabilization
• Record pressure
• Wait 9 minutes and record second pressure reading
• The difference between the two readings cannot exceed 0.4 PSI