My first reaction is the churn pressure is the normal working pressure. If you follow NFPA 20, the jockey pump is to be set at the churn pressure of the fire pump. So normally, the jockey pump can maintain the churn pressure on the system.
Now to install a PRV for 3 psig???????????? In most of the areas we work, we also have to adjust to the pressure ratings to the high hydraulic gradient for the water supply. John John August Denhardt, P.E., FSFPE Strickland Fire Protection Incorporated 5113 Berwyn Road College Park, Maryland 20740 Office Telephone Number: 301-474-1136 Mobile Telephone Number: 301-343-1457 FIRE SPRINKLERS SAVE LIVES - Can you live without them? -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Tuesday, February 18, 2014 2:50 PM To: [email protected] Subject: Static Pressure/Working Pressure 3.8.1.9.2 Static Pressure. The pressure that exists at a given point under normal distribution system conditions measured ... We have a project with an electric pump and when combined with the current water supply the churn pressure is 178 psi. A nationally known engineering firm wants us to install PRV's on the lowest level of the building because of the 3 psi. Our position is that the pressure only exists at churn and that is similar to an overnight pressure surge in a municipal water system. The over pressure will be compensated for by the pressure relief valves once the pump stops. Are we being overly loose with our interpretation of "normal" or is the engineering firm correct? Ron F _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
