Ouch, I had that feeling. Don't forget to have a way to full flow test after the PRV's if you go that way. And PRV's have a 25 or 30 psi required differential so if you don't have that safety in your calcs it could become much more complicated.
Chris -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Tuesday, February 18, 2014 3:45 PM To: [email protected] Subject: RE: Static Pressure/Working Pressure There are like 1200-1500 heads on the lower level. I can have the impeller shaved for $3-5k by the time it's done or add some PRV's, not sure exactly how many right now. It's all wet system (Phoenix, AZ) so dry valves not are an issue. Ron F -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Cahill, Christopher Sent: Tuesday, February 18, 2014 2:39 PM To: [email protected] Subject: RE: Static Pressure/Working Pressure Brad, you are confusing test pressure with working pressure. Test it to 1,000 psi and you are still limited to the working pressure of nominal 175 (or higher if the listed working pressure is higher). Ron, is there any component not listed to 250? You mention sprinklers. They make 250's I'm sure you know. I seem to recall dry valves hard to find over 175. I can't think of anything else that is not getable. Chris -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Brad Casterline Sent: Tuesday, February 18, 2014 3:33 PM To: [email protected] Subject: RE: Static Pressure/Working Pressure I would request all stakeholders consider a 2 hour hydrostatic test at 178+50=228 psi. brad -----Original Message----- From: Matsuda, Richard [mailto:[email protected]] Sent: Tuesday, February 18, 2014 3:22 PM To: [email protected] Subject: RE: Static Pressure/Working Pressure Ron, 1. The engr firm is correct...anything over 175-psi requires a PRV and the maximum expected static pressure (churn pressure) is used to determine where the PRV's are required. 2. If you do not put the PRV and something starts to leak and cause water damage, then you will assume responsibility. 3. I agree with you 100%...that the churn pressure only exists during the pump tests and that a city water supply may vary as much as 10 to 15-psi during the day so most of the time it will actually be less than 175-psi. 4. I also feel that installing a PRV for the "excessive" 3-psi is a waste of time and money. The hydrant test was done with a gauge that was bouncing around between 4 to 6-psi, and what if it was only 176-psi instead of 178-psi. However, I am not the responsible party to address this issue from a liability perspective. rick -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Tuesday, February 18, 2014 1:50 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 _______________________________________________ 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 _______________________________________________ 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
