We are inspecting an existing fire sprinkler building for an upgrade to an Extra Large Orifice (ELO) system.
We performed a hydrant flow test and noticed a 14 psi static loss between the hydrant, 185-ft of 8-inch ductile, 2 elbows and 8 feet of elevation rise to the supply side of the RPZ backflow preventer. We recorded 73 psi at hydrant and 59 psi at the number 1 test cock on the RPZ while static.
I spoke with the water authority and they confirmed no meter or check valve on the 8" fire line; it is straight into the valve room plus 2 elbows. The building is 20 years old and the pump test provided 120% of rated capacity.
Any idea how the static pressure inside the building is 14 psi less?
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