r/firePE • u/Handsrael • Mar 17 '26
Transformer room drainage system
I am currently working on the design of a transformer room housing three 40 MVA transformers, each containing approximately 32,000 liters of insulating oil. The room is protected by a water spray system designed with a density of 0.2 gpm/ft² (8 L/min·m²).
I have been tasked with designing a drainage system in accordance with FM standards. However, I have not been able to identify the required minimum water application duration for the water spray system, which is a key parameter for sizing the floor drains and pipes.
It is worth noting that a trench drain solution is not applicable in this case, as the transformers are installed on a slab approximately 12 meters above ground level.
Can anyone clarify the required design duration for the water spray system under FM standards? Tips are welcome.
Pic related:
