I was discussing leaving the suction side of a flooded processing system open at all times to insure no liquid was trapped in it during cleanup. A person in authority, but not an engineer by any means, asked if I was worried about "vapor freeze". I have been around industrial refrigeration now for 30+ years but have never heard that term or experienced anything that it would describe. Is there such a thing? and how would it effect a 3 inch suction line running +5psig house pressure. The liquid feed to this piece of eauipment is closed prior to clean up.