When should a check valve be installed in the discharge line of an ammonia system?

A check valve should be installed in the discharge line of an ammonia system when the system contains more than a specified amount of refrigerant, such as 40 lbs in this case. The purpose of this requirement is to prevent backflow into the compressor, which is crucial for maintaining system efficiency and preventing potential damage to the compressor and other components of the refrigeration system.

The presence of a check valve allows for the controlled and effective management of refrigerant flow, thereby ensuring that pressure and system integrity are maintained. In systems with larger volumes of refrigerant, the risk of issues arising from backflow is greater, making the installation of a check valve an important safety and operational measure.

This consideration aligns with best practices in ammonia refrigeration systems, where the handling of refrigerants must adhere to specific safety guidelines due to the potential hazards associated with ammonia.