This ammonia refrigeration process is equipped with an oil transfer pump that transfers fresh refrigeration oil from a barrel to fill up the compressor oil separators to the operating oil level. However, the oil pump has been idle for a prolonged period, with the electrical power connection incomplete.
Conversely, the associated piping system seems completed. One end of the oil distribution header is connected to the oil transfer pump discharge port. In contrast, the other end is connected to an oil recovery vessel which is always under the ammonia vapor suction pressure at 28 psi as per the pressure gauge reading.
The mechanical seal inside the oil pump is relatively dry, and lacks oil lubrication to form a proper seal. Therefore, ammonia vapor under pressure could easily escape through the tiny clearance between the stationary and rotating rings of the mechanical seal to the atmosphere into the machinery room.