The gasket on the suction valve cover failed
The gasket on the suction valve cover failed allowing ammonia to release into the machinery room which set off the ammonia alarm at approximately 05:00 hours. Qualified personnel responded to find the sensor reading at approximately 400 ppm. This compressor experienced a leak at the same location on November 6, 2019.
The ammonia enters the compressor through the suction valve which is designed with a cover plate that is removable. The gasket (approximately 0.020” thick) is located between the valve body and the cover and has four holes for the bolted connection. The gasket failed at one of the bolt holts.