RE: Change in static pressure
After doing the math the pressure loss can be accounted for by the change in elevation and the loss through the backflow at the low flow. I was unaware of the loss in pressure with no/little flow on the BFP. Thanks for everyone's input on the matter. Dewayne -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dewayne Martinez Sent: Friday, May 09, 2008 1:59 PM To: sprinklerforum@firesprinkler.org Subject: RE: Change in static pressure Thanks, I will look into the cut sheet. The fitter preformed an alarm test so only a small amount of water was flown. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Paul Pinigis Sent: Friday, May 09, 2008 1:22 PM To: sprinklerforum@firesprinkler.org Subject: RE: Change in static pressure Look at the cut sheet on the BFP. Some BFPs require a significant amount of pressure to open at very low flows. For example, an 12 Ames 2000SS requires almost 6 psi to operate at very low flow so it can sit there all day with an upstream pressure nearly 6 psi higher than the system side pressure. Paul J. Pinigis, P.E. Chief Life Safety Engineer -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dewayne Martinez Sent: Friday, May 09, 2008 1:55 PM To: sprinklerforum@firesprinkler.org Subject: Change in static pressure I have a job site which is 10ft higher than the water supply. A gauge on the water supply hydrant reads 55 PSI static pressure while two gauges on the system riser after the BFP read 37 PSI? The total elevation change between the system gauges and the supply gauge is about 17ft. Why would there be a 18 PSI difference between the gauges when elevation only accounts for 7.36 PSI? I confirmed with the city that there are no shut valves. Any thoughts? Thanks, Dewayne ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
RE: Change in static pressure
It would be interesting if you make a flow near the riser, take static and residual pressure next to the riser and on the street hydrant (simultaneously) and then note the differences. Dan -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dewayne Martinez Sent: Monday, May 12, 2008 2:30 PM To: sprinklerforum@firesprinkler.org Subject: RE: Change in static pressure After doing the math the pressure loss can be accounted for by the change in elevation and the loss through the backflow at the low flow. I was unaware of the loss in pressure with no/little flow on the BFP. Thanks for everyone's input on the matter. Dewayne -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dewayne Martinez Sent: Friday, May 09, 2008 1:59 PM To: sprinklerforum@firesprinkler.org Subject: RE: Change in static pressure Thanks, I will look into the cut sheet. The fitter preformed an alarm test so only a small amount of water was flown. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Paul Pinigis Sent: Friday, May 09, 2008 1:22 PM To: sprinklerforum@firesprinkler.org Subject: RE: Change in static pressure Look at the cut sheet on the BFP. Some BFPs require a significant amount of pressure to open at very low flows. For example, an 12 Ames 2000SS requires almost 6 psi to operate at very low flow so it can sit there all day with an upstream pressure nearly 6 psi higher than the system side pressure. Paul J. Pinigis, P.E. Chief Life Safety Engineer -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dewayne Martinez Sent: Friday, May 09, 2008 1:55 PM To: sprinklerforum@firesprinkler.org Subject: Change in static pressure I have a job site which is 10ft higher than the water supply. A gauge on the water supply hydrant reads 55 PSI static pressure while two gauges on the system riser after the BFP read 37 PSI? The total elevation change between the system gauges and the supply gauge is about 17ft. Why would there be a 18 PSI difference between the gauges when elevation only accounts for 7.36 PSI? I confirmed with the city that there are no shut valves. Any thoughts? Thanks, Dewayne ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) __ NOD32 3092 (20080512) Information __ This message was checked by NOD32 antivirus system. http://www.eset.com ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
Change in static pressure
I have a job site which is 10ft higher than the water supply. A gauge on the water supply hydrant reads 55 PSI static pressure while two gauges on the system riser after the BFP read 37 PSI? The total elevation change between the system gauges and the supply gauge is about 17ft. Why would there be a 18 PSI difference between the gauges when elevation only accounts for 7.36 PSI? I confirmed with the city that there are no shut valves. Any thoughts? Thanks, Dewayne ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
RE: Change in static pressure
Gage calibration is my 1st thought. Check all the gages or use your own calibrated gages. Art ATCO/Tiroly -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dewayne Martinez Sent: Friday, May 09, 2008 1:55 PM To: sprinklerforum@firesprinkler.org Subject: Change in static pressure I have a job site which is 10ft higher than the water supply. A gauge on the water supply hydrant reads 55 PSI static pressure while two gauges on the system riser after the BFP read 37 PSI? The total elevation change between the system gauges and the supply gauge is about 17ft. Why would there be a 18 PSI difference between the gauges when elevation only accounts for 7.36 PSI? I confirmed with the city that there are no shut valves. Any thoughts? Thanks, Dewayne ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
RE: Change in static pressure
Perhaps there is trapped thermal pressure or surge pressure on the system side of the BFP. Russell R -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dewayne Martinez Sent: Friday, May 09, 2008 1:55 PM To: sprinklerforum@firesprinkler.org Subject: Change in static pressure I have a job site which is 10ft higher than the water supply. A gauge on the water supply hydrant reads 55 PSI static pressure while two gauges on the system riser after the BFP read 37 PSI? The total elevation change between the system gauges and the supply gauge is about 17ft. Why would there be a 18 PSI difference between the gauges when elevation only accounts for 7.36 PSI? I confirmed with the city that there are no shut valves. Any thoughts? Thanks, Dewayne ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) No virus found in this incoming message. Checked by AVG. Version: 7.5.524 / Virus Database: 269.23.11/1422 - Release Date: 5/8/2008 5:24 PM No virus found in this outgoing message. Checked by AVG. Version: 7.5.524 / Virus Database: 269.23.11/1422 - Release Date: 5/8/2008 5:24 PM ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
RE: Change in static pressure
Look at the cut sheet on the BFP. Some BFPs require a significant amount of pressure to open at very low flows. For example, an 12 Ames 2000SS requires almost 6 psi to operate at very low flow so it can sit there all day with an upstream pressure nearly 6 psi higher than the system side pressure. Paul J. Pinigis, P.E. Chief Life Safety Engineer -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dewayne Martinez Sent: Friday, May 09, 2008 1:55 PM To: sprinklerforum@firesprinkler.org Subject: Change in static pressure I have a job site which is 10ft higher than the water supply. A gauge on the water supply hydrant reads 55 PSI static pressure while two gauges on the system riser after the BFP read 37 PSI? The total elevation change between the system gauges and the supply gauge is about 17ft. Why would there be a 18 PSI difference between the gauges when elevation only accounts for 7.36 PSI? I confirmed with the city that there are no shut valves. Any thoughts? Thanks, Dewayne ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
Re: Change in static pressure
Dwayne, Were the pressures read on the gauges on the hydrant and the BFP at the same time? Was any water flowing when these were read? We had a situation recently where we had differing pressures and what we found out was that the city had a 30 psi fluctuation in the street they did not know about. Todd At 01:54 PM 5/9/2008, you wrote: I have a job site which is 10ft higher than the water supply. A gauge on the water supply hydrant reads 55 PSI static pressure while two gauges on the system riser after the BFP read 37 PSI? The total elevation change between the system gauges and the supply gauge is about 17ft. Why would there be a 18 PSI difference between the gauges when elevation only accounts for 7.36 PSI? I confirmed with the city that there are no shut valves. Any thoughts? Thanks, Dewayne ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) Todd G. Williams, PE Fire Protection Design/Consulting Stonington, Connecticut www.fpdc.com 860.535.2080 ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
RE: Change in static pressure
No, they were not read at the same time. The gauges on the BFP were read last night and the hydrant information was read this morning by the city water department. This is starting to make sense now. The fire department said that the water tower is refilled at night so this might account for the missing PSI. I will go back out to the job in the morning to check the gauges again to see what they read then. Thanks, Dewayne -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Todd Williams - FPDC Sent: Friday, May 09, 2008 1:33 PM To: sprinklerforum@firesprinkler.org Subject: Re: Change in static pressure Dwayne, Were the pressures read on the gauges on the hydrant and the BFP at the same time? Was any water flowing when these were read? We had a situation recently where we had differing pressures and what we found out was that the city had a 30 psi fluctuation in the street they did not know about. Todd At 01:54 PM 5/9/2008, you wrote: I have a job site which is 10ft higher than the water supply. A gauge on the water supply hydrant reads 55 PSI static pressure while two gauges on the system riser after the BFP read 37 PSI? The total elevation change between the system gauges and the supply gauge is about 17ft. Why would there be a 18 PSI difference between the gauges when elevation only accounts for 7.36 PSI? I confirmed with the city that there are no shut valves. Any thoughts? Thanks, Dewayne ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) Todd G. Williams, PE Fire Protection Design/Consulting Stonington, Connecticut www.fpdc.com 860.535.2080 ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
RE: Change in static pressure
Thanks, I will look into the cut sheet. The fitter preformed an alarm test so only a small amount of water was flown. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Paul Pinigis Sent: Friday, May 09, 2008 1:22 PM To: sprinklerforum@firesprinkler.org Subject: RE: Change in static pressure Look at the cut sheet on the BFP. Some BFPs require a significant amount of pressure to open at very low flows. For example, an 12 Ames 2000SS requires almost 6 psi to operate at very low flow so it can sit there all day with an upstream pressure nearly 6 psi higher than the system side pressure. Paul J. Pinigis, P.E. Chief Life Safety Engineer -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dewayne Martinez Sent: Friday, May 09, 2008 1:55 PM To: sprinklerforum@firesprinkler.org Subject: Change in static pressure I have a job site which is 10ft higher than the water supply. A gauge on the water supply hydrant reads 55 PSI static pressure while two gauges on the system riser after the BFP read 37 PSI? The total elevation change between the system gauges and the supply gauge is about 17ft. Why would there be a 18 PSI difference between the gauges when elevation only accounts for 7.36 PSI? I confirmed with the city that there are no shut valves. Any thoughts? Thanks, Dewayne ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
Re: Change in static pressure
The BFP should trap the highest pressure on the system side so that the up and down fluctuations will happen on the supply side. This will read the same as the two gages on an alarm check valve when it is acting as the only system/supply check. The water tower seems the culprit. The elevation difference accounts for 7.4 psi. The remaining 10.6 psi could be the tank if the before refill/after refill elevation inside the tank is 24.5 feet. On Fri, May 9, 2008 at 11:59 AM, Dewayne Martinez [EMAIL PROTECTED] wrote: Thanks, I will look into the cut sheet. The fitter preformed an alarm test so only a small amount of water was flown. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Paul Pinigis Sent: Friday, May 09, 2008 1:22 PM To: sprinklerforum@firesprinkler.org Subject: RE: Change in static pressure Look at the cut sheet on the BFP. Some BFPs require a significant amount of pressure to open at very low flows. For example, an 12 Ames 2000SS requires almost 6 psi to operate at very low flow so it can sit there all day with an upstream pressure nearly 6 psi higher than the system side pressure. Paul J. Pinigis, P.E. Chief Life Safety Engineer -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dewayne Martinez Sent: Friday, May 09, 2008 1:55 PM To: sprinklerforum@firesprinkler.org Subject: Change in static pressure I have a job site which is 10ft higher than the water supply. A gauge on the water supply hydrant reads 55 PSI static pressure while two gauges on the system riser after the BFP read 37 PSI? The total elevation change between the system gauges and the supply gauge is about 17ft. Why would there be a 18 PSI difference between the gauges when elevation only accounts for 7.36 PSI? I confirmed with the city that there are no shut valves. Any thoughts? Thanks, Dewayne ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) -- Ron Greenman at home ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
RE: Change in static pressure
If water was flowed on the system side of the BFP there can be a lower pressure on the system side vs. the supply side due to the on-off action of some axial-check BFPs. This is not the same phenomenon as the pressure difference across an ACV because the ACV uses a simple side-hinged check. Paul J. Pinigis, P.E. Chief Life Safety Engineer -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ron Greenman Sent: Friday, May 09, 2008 3:33 PM To: sprinklerforum@firesprinkler.org Subject: Re: Change in static pressure The BFP should trap the highest pressure on the system side so that the up and down fluctuations will happen on the supply side. This will read the same as the two gages on an alarm check valve when it is acting as the only system/supply check. The water tower seems the culprit. The elevation difference accounts for 7.4 psi. The remaining 10.6 psi could be the tank if the before refill/after refill elevation inside the tank is 24.5 feet. On Fri, May 9, 2008 at 11:59 AM, Dewayne Martinez [EMAIL PROTECTED] wrote: Thanks, I will look into the cut sheet. The fitter preformed an alarm test so only a small amount of water was flown. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Paul Pinigis Sent: Friday, May 09, 2008 1:22 PM To: sprinklerforum@firesprinkler.org Subject: RE: Change in static pressure Look at the cut sheet on the BFP. Some BFPs require a significant amount of pressure to open at very low flows. For example, an 12 Ames 2000SS requires almost 6 psi to operate at very low flow so it can sit there all day with an upstream pressure nearly 6 psi higher than the system side pressure. Paul J. Pinigis, P.E. Chief Life Safety Engineer -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dewayne Martinez Sent: Friday, May 09, 2008 1:55 PM To: sprinklerforum@firesprinkler.org Subject: Change in static pressure I have a job site which is 10ft higher than the water supply. A gauge on the water supply hydrant reads 55 PSI static pressure while two gauges on the system riser after the BFP read 37 PSI? The total elevation change between the system gauges and the supply gauge is about 17ft. Why would there be a 18 PSI difference between the gauges when elevation only accounts for 7.36 PSI? I confirmed with the city that there are no shut valves. Any thoughts? Thanks, Dewayne ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) -- Ron Greenman at home ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
RE: Change in static pressure
If the solution is not evident when you re-check, have the city put a pressure recorder on the hydrant. That will show the ups and downs over a period of time. In my situation it was 3 tanks that filled at random times. At 02:57 PM 5/9/2008, you wrote: No, they were not read at the same time. The gauges on the BFP were read last night and the hydrant information was read this morning by the city water department. This is starting to make sense now. The fire department said that the water tower is refilled at night so this might account for the missing PSI. I will go back out to the job in the morning to check the gauges again to see what they read then. Thanks, Dewayne -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Todd Williams - FPDC Sent: Friday, May 09, 2008 1:33 PM To: sprinklerforum@firesprinkler.org Subject: Re: Change in static pressure Dwayne, Were the pressures read on the gauges on the hydrant and the BFP at the same time? Was any water flowing when these were read? We had a situation recently where we had differing pressures and what we found out was that the city had a 30 psi fluctuation in the street they did not know about. Todd At 01:54 PM 5/9/2008, you wrote: I have a job site which is 10ft higher than the water supply. A gauge on the water supply hydrant reads 55 PSI static pressure while two gauges on the system riser after the BFP read 37 PSI? The total elevation change between the system gauges and the supply gauge is about 17ft. Why would there be a 18 PSI difference between the gauges when elevation only accounts for 7.36 PSI? I confirmed with the city that there are no shut valves. Any thoughts? Thanks, Dewayne ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) Todd G. Williams, PE Fire Protection Design/Consulting Stonington, Connecticut www.fpdc.com 860.535.2080 ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) Todd G. Williams, PE Fire Protection Design/Consulting Stonington, Connecticut www.fpdc.com 860.535.2080 ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
Re: Change in static pressure
My thought is open up the BFP and check for rocks. The one time I've seen odd numbers at the BFP it was due to rocks introduced by the site plumber altering the incoming service unbeknownst to the fire protection contractor who had already installed his stuff. Using the numbers given, 55 at the street is 47.6 at the BFP. The system side can drop below 47.6 because at the check valve the check area exposed to the street pressure is smaller than the check area exposed to the system pressure. A system pressure smaller than 47.6 will hold the check closed against the street because that smaller system pressure is acting on a check area larger than the check area the street is acting on. This happens twice in a double check. That accounts for some of pressure difference. Now add some rocks on the system side in the BFP that act in favor of the system side. Maybe that is what is going on and maybe not, but keep in mind that all the rest of the system in question is just plain pipe and valves. The only unknown mechanism involved is what is inside the BFP. Allan Seidel St. Louis, MO On May 9, 2008, at 12:54 PM, Dewayne Martinez wrote: I have a job site which is 10ft higher than the water supply. A gauge on the water supply hydrant reads 55 PSI static pressure while two gauges on the system riser after the BFP read 37 PSI? The total elevation change between the system gauges and the supply gauge is about 17ft. Why would there be a 18 PSI difference between the gauges when elevation only accounts for 7.36 PSI? I confirmed with the city that there are no shut valves. Any thoughts? Thanks, Dewayne ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:Sprinklerforum- [EMAIL PROTECTED] (Put the word unsubscribe in the subject field) ___ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
