my name is Grzegorz Boguszewski and I am a sprinkler designer.
I have a problem with one rule in NFPA20 version 2016 - Pump Station: the number of point is: 18.104.22.168.2 with folowing content:
"The total air supply path to the pump room shall not restrict the flow of the air
more than 0.2 in. water column (5.1 mm water column)."
In handbook there is no explanation and I don't know HOW should I maintain 5.1mm overpresure in pumping station ?