I agree with Kyle. Run a pitot on the main drain and figure the gpm that is running during the main drain test. If the GPM is lower than system demand the pressure should be higher that your system demand. If the GPM during the main drain test is higher than the system demand then the pressure should be lower. Pretty simple to figure out.
From: Kyle.Montgomery <[email protected]> Sent: Wednesday, September 11, 2024 10:33 AM To: Discussion list on issues relating to automatic fire sprinklers <[email protected]> Subject: [Sprinklerforum] Re: [External]main drain test Can you figure out how much water you are flowing (GPM) during the main drain test? If you are flowing the same amount or less than what your calculation requires, then the inspector may be onto something. If you are flowing a lot more water during the main drain test, then you could use that to explain to the inspector. Even better, throttle the drain until you are flowing the same volume required for your calculation and compare the pressures at that point. It probably wouldn't be TOO difficult to get a pitot or a Hose Monster or something hooked up to the drain discharge. I know that's not really what main drain tests are intended for, but if the system was really deficient, would you want to know and get it corrected? And if it's not deficient, then it clears that up for the inspector and the owner can stop spending money at that point. Kyle Montgomery [cid:[email protected]] Aero Automatic Sprinkler Co. 21605 N. Central Ave. Phoenix, AZ 85024 Direct: 623.580.7820 Cell: 602.763.4736 [email protected]<mailto:[email protected]> From: Rocci 3 Cetani <[email protected]<mailto:[email protected]>> Sent: Wednesday, September 11, 2024 7:18 AM To: [email protected]<mailto:[email protected]> Subject: [External][Sprinklerforum] main drain test We have a jurisdiction that failed our final inspection because the residual pressure during the main drain test doesn't match our BOR residual pressure from the hydraulic calcs for and OH extended coverage system. Am I missing something? I don't see how the residual pressure on a main drain test has anything to do with the residual pressure from our calcs.....I was always under the impression main drain tests were to verify there hasn't been a been a drastic change to the supply . This was an existing parking garage where they added solar panels on the top level so we added a sectional riser @ the top floor and added the new system. The fire department just keeps saying to upsize the riser from the 1st floor to the 4th floor which literally does nothing to my calcs. The building owner has spent 10's of thousands of dollars flushing the UG, inspecting the UG for obstructions, paid for additional flow test and serviced the back flow. We are at a complete loss on what else to do as the fire department is adamant that's the main drain test has to match the hydraulic calcs.....anyone ever come across a situation like this with a jurisdiction? Any suggestions? Rocci Cetani III Northern California Fire Protection Services Inc. 16840 Joleen Way Bldg. A Morgan Hill, CA 95037 P-(408) 776-1580 EXT.1010 F-(408) 776-1590 To help better serve you. Please visit our new and improved website at: www.norcalfire.com<http://www.norcalfire.com/> CONFIDENTIALITY NOTICE: This message and any document accompanying it may contain confidential information belonging to the sender. The information is intended only for the use of individual or entity named above. If you are not the intended recipient, or the employee or agent responsible to deliver this message to the intended recipient, you are hereby notified that any disclosure, copying or taking of any action in reliance on the contents of this information is strictly prohibited. If you have received this transmission in error, please immediately notify us by telephone to arrange for return of the documents.
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