Based on actual field testing done in Phoenix around twenty years ago I can attest to the disruption of the distribution pattern at ultra high pressures. We subjected extended coverage sidewall sprinklers to discharge pressures from 175 to 225 psi and found that around 210 psi the throw began to truncate as the extreme velocity of the discharge over the deflector began to atomize the spray into a mist. As I recall, we stopped the testing when the Sprinkler only produced a cloud of localized mist with very little projection beyond 6 to 8 feet.
Mark at Aero 602 820-7894 Sent from my iPhone On Jun 27, 2018, at 3:06 PM, AKS-Gmail-IMAP <[email protected]<mailto:[email protected]>> wrote: Nothing has broken yet and maybe will not, but I think you don’t get the right spray pattern out of over pressurized sprinklers. I understand the pattern starts to become directional. Perhaps this and the impact it could have on control performance has been pointed out to the parties involved. On Jun 27, 2018, at 3:39 PM, Prahl, Craig/GVL <[email protected]<mailto:[email protected]>> wrote: It is a problem when the contractor is telling an owner that there is no problem because their calculation shows the system only requiring 40 psi when we know system pressures are going to actually be in the 200 psi range. The issue is with designers who are not properly instructed on what the numbers mean in these calcs that they magically produce with a keystroke and with an owner who believes every word they say as absolute. Craig Prahl | Jacobs | Group Lead – Fire Protection | 864.676.5252 | [email protected]<mailto:[email protected]> | www.jacobs.com<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.jacobs.com_&d=DwMFaQ&c=wn3mZQLIuInh2ClcJ0_DIA&r=dLwiR71i_XhSFqam3ZLeaFLiQJ3cDTUB0ReB4-yDDcg&m=pxMOLBMSVbcej2vnhtddQcM2xWaqk5TqbCeJLHMAsqo&s=FUAFZIsCEmpkhDU-YiPw6d9aoNvZmLz1LEX6A5l-HE0&e=> From: Sprinklerforum [mailto:[email protected]] On Behalf Of Roland Huggins Sent: Wednesday, June 27, 2018 2:42 PM To: [email protected]<mailto:[email protected]> Subject: [EXTERNAL] Re: Real system pressures versus the calculations This is not an issue that is intended to be caught by the hydraulic calculations for the system demand. It is purely and simply a deficiency in the pump design (as already indicated by Matt). The original design was fine but when someone changed the water supply, THEY were responsible for ensuring the pump curve was still acceptable. This is also a problem for new systems when water supply modifiers are applied. You have to size the pump for both the sprinkler demand based on the lowest available supply pressure AND the churn limits based on the highest supply pressure. Roland Roland Huggins, PE - Senior VP Engineering American Fire Sprinkler Assn. Dallas, TX http://www.firesprinkler.org<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.firesprinkler.org_&d=DwMFaQ&c=OgZOSER8c1RLeytEexU279Q2qk0jVwkrOdYe5iSi-kk&r=6qYbbLx8x0UrMujmEGNoh-2hzoFD2d1EB5d2sQF0_OI&m=9t3lHhKjiD1mJlP5Tp1xAPihIkIokW1byvR67Hld0rY&s=EMtRTfazpYo9Jqx2Sw8CRcqLKHDKE_c9kkImir7w8dU&e=> Fire Sprinklers Saves Lives On Jun 27, 2018, at 8:21 AM, Prahl, Craig/GVL <[email protected]<mailto:[email protected]>> wrote: 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]> | www.jacobs.com<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.jacobs.com_&d=DwMFaQ&c=wn3mZQLIuInh2ClcJ0_DIA&r=dLwiR71i_XhSFqam3ZLeaFLiQJ3cDTUB0ReB4-yDDcg&m=pxMOLBMSVbcej2vnhtddQcM2xWaqk5TqbCeJLHMAsqo&s=FUAFZIsCEmpkhDU-YiPw6d9aoNvZmLz1LEX6A5l-HE0&e=> ________________________________________________________________________________________ NOTICE - This communication may contain confidential and privileged information that is for the sole use of the intended recipient. 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