NH3 Engine Room E-Stop(s)

NH3 Engine Room E-Stop(s)

Both OSHA and EPA through the PSM and RMP standard require written operating procedures.  The regulators also require a phase within the  procedures that is specific to emergency shutdown. The emergency shutdown procedures for a process must consider the following three:

  • the conditions under which the procedure is applicable
  • the assignment of shutdown responsibilities to qualified operators
  • the shutdown is executed in a safe and timely manner

Leading RAGAGEP (best practices) would be IIAR and it is found in Standard 2.  What is required at minimum for the E-stop when activated under this IIAR standard?

  • Off only control for compressors
  • Off only control for liquid pumps,
  • Off only control for normally closed automatic valves within the machinery room.

Some questions to your PSM team from GCAP

  • Has your training addressed who is and who is not qualified to perform an emergency shutdown?
  • Can an active leak become worse by activating the E-stop if the leak is on the suction side of the system?
  • Can an active leak become worse by activating the E-stop if the leak on the high side of the system?
  • Do you need more than 1 switch if you have more than one common door to engine room?
  • Can you get to the switch in an emergency situation?
  • How often are the switches tested?
  • After the switch is activated, what actually happens?
  • After the switch is activated, what are the remaining, if any, electrical sources in the mechanical room?
  • Does this switch disconnect power to the ammonia sensors?
  • Does this switch disconnect power to the exhaust system?