Got a call at 6 am this morning from a fishfactory nearby, they had an ammonia leak from a pipe on a tunnel/blast freezer that is not in use at the moment.

The engineer has been running the plant in manual to keep the suction pressure down all night, but whenever a defrost kicks in on a another part of the system and the suction pressure rises, the ammonia smell would get worse.

he knew there was a leak on the hotgas return line, because he had had the maintenance crew strip the insulation to paint the pipes, to check them after having "ammonia smell" around that area for 6 months

turned out the hotgas return valves were leaking back into the evaporator (old type danfoss)

This is the pipe where they had had the "ammonia smell" from time to time

20150505_090921.jpg

The hole was big enough for me to stick my finger through it, only thing keeping it somewhat closed was the insulation