Recently had a job with a wet-pipe fire sprinkler system (smaller project) that has a 6-inch double check backflow. The area static and residual pressures are pretty consistent (had a flow test of ~40 psi static and ~38 psi residual at 1,300 gpm).

We ran a forward-flow test through the backflow preventer, needing a minimum flow of about 800 gpm, which includes the hose allowances for the project (no standpipes or interior hose connections).

The most flow we could get was about 450 gpm, even with three 2-1/2" hose outlets completely wide open. The static pressure following the test at the riser was about 40 psi. We used three 100 ft, 2-1/2" hoses with a 1-3/4" smooth nozzle and diffusers at the end of each hose, measuring about 3 psi pitot on each and full flow (which equates to roughly 450 gpm).

Do you have any tips or advice in why we were not able to get enough flow through the backflow, or where to start to troubleshoot?

Thanks in advance!

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In an existing building utilizing a “booster pump” or unlisted fire pump for a standpipe or sprinkler system, is there a suggested annual flow test procedure?

I realize there is no manufacturer’s data (0%,100%,150% rated capacity) to compare the results against.

Should it be excluded from the annual flow test requirements, and just flowed during the 5 year roof top flow?

I would appreciate input as well as, what others in the industry are doing to address this fairly common scenario.

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A remote camp facility is being planned which intends to operate seasonally. Due to the remote nature of the site and lack of easy access to nearby mains, a water storage tank is being considered to supply the site fire sprinkler systems. It is intended to have atmospheric pressure, water temperature, water level, and heating system which are all supervised by a central station. During the offseason in the winter, what is the most frequent that these components must be inspected?
a. Weekly
b. Monthly
c. Quarterly
d. Semiannually

Solution | Posted 08/24/2020

​Annual inspection of wet barrel hydrants must include all of the following except:
a. verify marking of hydrant
b. verify outlet thread condition
c. verify access to hydrant
d. verify cracks in hydrant barrel

Solution | Posted 07/29/20

At what frequency shall a preaction sprinkler system valve be trip tested with the control valve fully open?
a. annually
b. every 3 years
c. every 5 years
d. every 10 years

Solution | Posted 07/20/20

Solution | Posted 07/10/20

Does anyone have any pressure maintenance pumps installed on their sprinkler systems without having a fire pump?

In other words, having a pump on the sprinkler system that is only there for the purposes of preventing a false alarm (due to pressure ebbs and spikes in the water supply) instead of boosting the water pressure like a traditional fire and jockey pump combination.

We have some legacy jockey pumps installed like this and it runs into a grey area for maintenance as they don't affect the performance of the sprinkler system they are connected to. Any thoughts?

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I have an inspection question regarding quarterly checks on low air supervisory devices on dry systems.

Is it okay to simply "jump off" the device when not doing a full or partial trip to simply make sure it hits the panel?

I feel like I'm doing a disservice inspecting using this method, but I've seen it a lot. Unfortunately for me, it's been a crapshoot lately on what dry valve is going to go haywire when I drop air via an Inspector's Test Valve or at the riser. I'm thinking of just recommending a bleeder valve to be installed and go the easy route, saving both myself and customers a lot of anxiousness.

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NFPA 25 requires a legible Hydraulic Information Sign.

How do I replace a missing Hydraulic Placard (or calculation plate/card) on an existing system? And what if there isn't original design information available?

I'm curious to see how others are addressing this deficiency.

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Looking for guidance on pressure gauge selection. Is there a requirement for a maximum pressure gauge for testing residual pressures of 40-50 psi on suppression systems?

Wondering if any pressure gauge is adequate or if there's specific guidance I should be following on gauge selection.

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When testing a fire pump from the roof is there a calculation that is necessary to ensure that the flow test is accurate (given pipe sizes, elevation increase, etc)?

NFPA 25, 2014 handbook states that flowing from the roof in the explanatory material is somewhat acceptable (NFPA 25, 2014: 8.3.3.1.3). However, NFPA 20, 2013 A.4.20.3.4(2) has a sample hydraulic calculation sheet for sizing the test header when not using the table which appears to take into account items like friction loss, elevation, etc.

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