What if fewer sprinklers open than in your design area? The pump and water supply aren’t going to know what the minimum sprinkler demand is and magically hold to that point while discharging no more.
I know you are well aware of this. The sprinkler calculations are demand calcs that give minimums. You can run supply calcs to determine what pressures and flows you can expect with the full water supply discharging. Travis Mack, SET MFP Design, LLC 3356 E Vallejo Ct Gilbert, AZ 85298 480-505-9271 fax: 866-430-6107 <mailto:email:[email protected]> email:[email protected] <https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.mfpdesign.com%2F&data=02%7C01%7C%7C1121d49f9e6b4cf248f108d4df580e77%7C14e5497c16da42e69ffa77d19bafe511%7C0%7C0%7C636379016677342180&sdata=HJ8OA4xyeHAoxXNz5mu%2FYfycgtd5nsFrrpvzulZiNkQ%3D&reserved=0> http://www.mfpdesign.com <https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.facebook.com%2Fpages%2FMFP-Design-LLC%2F92218417692&data=02%7C01%7C%7C1121d49f9e6b4cf248f108d4df580e77%7C14e5497c16da42e69ffa77d19bafe511%7C0%7C0%7C636379016677342180&sdata=H%2BwdcgK8DLGBcNoqJEvUrzsXngySwkX56Vgf9gM9EGk%3D&reserved=0> https://www.facebook.com/pages/MFP-Design-LLC/92218417692 Send large files to us via: <https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.hightail.com%2Fu%2FMFPDesign&data=02%7C01%7C%7C1121d49f9e6b4cf248f108d4df580e77%7C14e5497c16da42e69ffa77d19bafe511%7C0%7C0%7C636379016677342180&sdata=eGdMZGu2wXhUupGwgGTrqF3b54OP5%2BAZvlHhABSexWY%3D&reserved=0> https://www.hightail.com/u/MFPDesign LinkedIn: <https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.linkedin.com%2Fin%2Ftravismack&data=02%7C01%7C%7C1121d49f9e6b4cf248f108d4df580e77%7C14e5497c16da42e69ffa77d19bafe511%7C0%7C0%7C636379016677342180&sdata=tT5E7LsZjSmyreKi4gDCa70EWN%2BZodi%2FhbeCbHNRijI%3D&reserved=0> https://www.linkedin.com/in/travismack “The bitterness of poor quality remains long after the sweetness of low price is forgotten.” From: Sprinklerforum <[email protected]> On Behalf Of Prahl, Craig/GVL Sent: Wednesday, June 27, 2018 8:22 AM To: [email protected] Subject: Real system pressures versus the calculations I have a system that was originally designed with a fire pump taking suction from an elevated municipal water tank. At some point in time the system source was changed from the tank to a municipal water supply. This change has resulted in the system pressures being well over 200-250 psi. So far nothing has blown out, yet but numerous buildings and underground were built based on standard pressure rated components. The thought for the day is this, when you run a calculation, the output will show the minimum required pressure at the hydraulically most remote sprinkler that is required to provide the design flow rate. The calculations also show the deviation between Required and Available system pressures. So, when the fire pump kicks on, what the system ACTUALLY sees is the rated pressure of the pump being introduced into the system, not the minimum required pressure that is shown in the calculations, Agreed? If it is stated that in the calculations that the pressure at the sprinklers on an upper floor will be less than 175 psi but those on the lower floor will be greater is it safe to assume based on the ACTUAL pressures coming out of the pump that the entire system will likely see pressures exceeding 175 psi? Looking for some thoughts. Craig Prahl | Jacobs | Group Lead – Fire Protection | 864.676.5252 | [email protected] <mailto:[email protected]> | <http://www.jacobs.com/> www.jacobs.com ________________________________________________________________________________________ NOTICE - This communication may contain confidential and privileged information that is for the sole use of the intended recipient. Any viewing, copying or distribution of, or reliance on this message by unintended recipients is strictly prohibited. If you have received this message in error, please notify us immediately by replying to the message and deleting it from your computer.
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