This post is a follow-up to my earlier post about NH3 being a CAT 2 Flammable Gas, as there are still businesses that dont fully grasp the full hazard profile of NH3. The fact that the facility is under the OSHA/RMP TQ of 10,000 pounds has NOTHING to do with needing the engine/mechanical room to be “adequately ventilated” in order to exempt the space from being a Class 1, Div 2, Group D HAZLOC using the NFPA 70 exemption.
Some may be surprised that just 226 pounds of NH3 is all that is needed to achieve the 16% LEL of NH3 in that size of space. A far cry from the 10,000 pound PSM/RMP TQ. Don’t believe me? Here are the numbers…
NOTE: Electrical Classifications and Ventilation are NOT driven by PSM/RMP requirements. Both of the Active and Passive Engineering Controls have been around LONG before PSM/RMP. Yes, they are both required for PSM/RMP covered process; however, BOTH are required for almost all areas handling/processing flammable liquids/gases, regardless of PSM/RMP Thresholds.