The city of Boston requires low street pressure switches on ALL sprinkler systems, regardless of flavor. These also have to be installed before any shutoffs, and typically have a bleeder valve and gauge. They're supposed to be activated at 20 PSI and signal supervisory and usually do not latch. This has been a local requirement going back to the 80's. We often set them off while commissioning manual standpipes using a pumper drafting off a hydrant (usually when wired to alarm by mistake). Fire pumps can be another animal, especially engine driven and cooled, whether equipped with a suction control valve or not. Depending on start method, engines can stop themselves both on low oil and high temperature. But, these actions will generate an alarm condition to the controller and hopefully alarm system. TD
> On 01/06/2026 8:50 AM EST John Denhardt <[email protected]> wrote: > > > Great points Mike. The newer (and more expensive equipment) do offer some > options as long as the AHJ approves their use. > > Keep in mind, a fire pump system is designed to run to destruction if it is > needed to. This includes a low pressure suction condition. > > Thanks, > John > > > John August Denhardt, P.E > > Vice President Engineering and Technical Services > American Fire Sprinkler Association > 301-343-1457 > > Are you a member with a technical question? > Don't forget one of the most valuable resources that AFSA provides is > Technical Reviews by our Technical Services Department. It’s like having an > FPE on your staff. Visit www.firesprinkler.org/technicalreview > https://www.firesprinkler.org/technicalreview to submit a question today! > (Member login required.) > > On Jan 6, 2026, at 08:13, Mike Morey <[email protected]> wrote: > > > In fairness, there are a couple other options today, most controllers now can > be configured for a low suction shutoff if allowed by the AHJ (however this > is rarely an acceptable option) and pressure limiting drive (PLD) diesels can > have a low suction throttle in their controller (this is becoming pretty > common as the added transducer and controls are typically cheaper than the > valve, and you aren’t adding loss etc). But typically, when someone says > “low suction alarm” it’s just as you say, a buzzer/supervisory signal and no > action is taken by the controller. > > > > Mike Morey > > 2025 NFSA Top Tech Champion > https://url.usb.m.mimecastprotect.com/s/1KKZCN7oZqS1EyDpumfKHyntZ4?domain=linkedin.com/ > • NICET IV > https://url.usb.m.mimecastprotect.com/s/VoIUCOJp1rto0QzkIvhZHGRUph?domain=credentials.nicet.org > • CFPS > https://url.usb.m.mimecastprotect.com/s/r02gCP6q2vHqoV8ns1iOHxtwPY?domain=credly.com > > Project Estimator • Fire Protection Group > Shambaugh & Son, LP an EMCOR Company > > 7614 Opportunity Drive • Fort Wayne, IN • 46825 > > direct 260.487.7824 / cell 260.417.0625 > email [email protected] mailto:[email protected] > 24/7 SERVICE LINE 888.217.7055 tel:888.217.7055 > > <image001.png> > > > > > > From: John Denhardt <[email protected]> > Sent: Tuesday, January 6, 2026 7:42 AM > To: [email protected] > Subject: [Sprinklerforum] Re: LOW SUCTION PRESSURE > > > > Low suction alarm? Low suction valve? A low pressure alarm is just an alarm > or supervisory alarm. No impact to the fire pump system as it will run to > destruction. A low suction valve will restrict the discharge to limit water > flow rate to prevent > > ZjQcmQRYFpfptBannerStart > > This Message Is From an External Sender > > This message originated outside your organization. > > ZjQcmQRYFpfptBannerEnd > > Low suction alarm? Low suction valve? > > > > A low pressure alarm is just an alarm or supervisory alarm. No impact to the > fire pump system as it will run to destruction. > > > > A low suction valve will restrict the discharge to limit water flow rate to > prevent a low suction situation. The fire pump system (including a diesel > driver) will only see lesser water flow. > > > > I hope this helps. Feel free to call me to discuss further. > > > > Thanks, > > John > > > > John August Denhardt, P.E > > > Vice President Engineering and Technical Services > > American Fire Sprinkler Association > > 301-343-1457 > > > > Are you a member with a technical question? > > Don't forget one of the most valuable resources that AFSA provides is > Technical Reviews by our Technical Services Department. It’s like having an > FPE on your staff. Visit www.firesprinkler.org/technicalreview > https://url.usb.m.mimecastprotect.com/s/yeaDCR8v4xi8RZjXiqtKH1sxzm?domain=urldefense.com > to submit a question today! (Member login required.) > > > On Jan 6, 2026, at 07:33, [email protected] mailto:[email protected] > wrote: > > > _________________________________________________________ > SprinklerForum mailing list: > https://lists.firesprinkler.org/list/sprinklerforum.lists.firesprinkler.org > https://url.usb.m.mimecastprotect.com/s/3iihCWWAgDsvPoR8i1C2Ho_V__?domain=urldefense.com > To unsubscribe send an email to [email protected] > mailto:[email protected] > > Does a low suction pressure alarm have any affect on the diesel fire pump’s > engine control? > > This message is for the named person's use only. It may contain confidential, > proprietary or legally privileged information. No confidentiality or > privilege is waived or lost by any mistransmission. If you receive this > message in error, please immediately delete it and all copies of it from your > system, destroy any hard copies of it and notify the sender. You must not, > directly or indirectly, use, disclose, distribute, print, or copy any part of > this message if you are not the intended recipient. > > _________________________________________________________ > SprinklerForum mailing list: > https://url.usb.m.mimecastprotect.com/s/32rnCVJz8Bt15QN8ukuvHE-k5t?domain=lists.firesprinkler.org > To unsubscribe send an email to [email protected] > > _________________________________________________________ > SprinklerForum mailing list: > https://lists.firesprinkler.org/list/sprinklerforum.lists.firesprinkler.org > To unsubscribe send an email to [email protected] >
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