RETA Breeze Jul-Aug 2025

too far or document too little. In my opinion, you need a material specification for the plant, including pipe specifications, valve specifications, etc. There is a huge bonus to this. If you limit the type of valves, compres sors, pumps, etc., your training becomes easier because there are less items you need to train on. The problem you will run into is enforcing those outside of your facility (contractors) to stay within this. You will need to ensure that they have this informa tion up front. PIPING AND INSTRUMENT DIAGRAMS (P&IDS) Piping and instrumentation diagrams are the heart of the PSI. They need to be accurate and they need to be maintained current. Too many times, we find that the P&IDs do not show correct valving. Valve lists are normally built from the P&IDs as are SOPs. If the P&IDs are incorrect chances are that there are many items which need updates as well. I recommend that a full review of the ramifications be conducted whenever errors are found in the P&IDs. ELECTRICAL CLASSIFICATION Normally when we talk about electrical classifi cation, we are talking about the engine room electrical classification. This isn’t just a BS docu ment. It is vital that we know what our electrical classification is for the engine room. It is also vital that our personnel understand electrical classification in other areas. Do we have wash down areas where refrigeration equipment is located? How do we docu ment these classifications? How do we maintain them? Think about the nightmare caused when a new ammonia detection system, designed for a dry area, gets washed down every night. Getting called in the middle of the night because sanitation sprayed them and now the alarm is going off makes me grumpy after a while. RELIEF SYSTEM DESIGN AND DESIGN BASIS This document provides verification that your relief system is adequately sized. Always verify modifications to this docu ment. Many times, what is installed in the field does not match what is in the design document. Sometimes inspectors will physically measure the piping. Don’t forget about pipe schedules. Schedule 80 pipe has how to maintain that classification. Many facilities are starting to look at

Example of a Simplified Process Flow Diagram

Appendix B to § 1910.119

Example of a Simplified Process Flow Diagram

system doesn’t care where the heat is coming from. The heat from a 500 hp air compressor and a 500 hp ammonia compressor looks the same to the ventilators. Ventilation system calculations can quickly be outdated. Pay special attention to engine room ventilation calculations during the MOC process. How do you go from good to great? Consider incorporating ventilation calcula tions for process areas. Air balancing has a huge effect on refrigeration. Food safety may also have an interest in air balancing and ventilation in the process areas. It may be a good idea to incorporate these air balances into the PSM program to ensure they are updated as ventilation is modified. Sarah Selzer, CARO is a Compliance Specialist for APSM. Her opinions are her own and do not necessarily reflect those of her team mates at APSM. She has the distinction of having held a RETA chapter office as a teenager, the privilege of growing up in a refrigeration contracting firm, and the curse of thinking about refrigeration compliance all the time. Sarah is a 2024 RETA 30 Under 30 winner. Volume 3b of this Compliance article will appear in the September/October edition of The RETA Breeze .

a different ID than schedule 40. All of this can affect the calculation. Also, obtain editable files from your contractors; it’s your system. I would be very hesitant to pay a contractor that doesn’t provide something I can update in the future. I recently heard of a contractor who charged near $20,000 to perform a calculation and then refused to turn over editable documents. This forces you to utilize them for future projects. VENTILATION SYSTEM DESIGN This is similar to relief system designs. Normally when we talk about ventilation, we are talking about engine room ventila tion. This calculation is required to be kept on file and updated when any of the parameters are updated. Those parameters are: maximum intended inventory, motor horsepower in the engine room and engine room size. Therefore, when calculating engine room horsepower, do you: 1. Count only ammonia compressors? 2. Count all ammonia refrigeration equipment? 3. Count all horsepower in the room regardless of the source? You count all the horsepower in the room regardless of the source. The ventilation

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