We have a 6-story condo building. It's an NFPA 13 system on the first floor, and NFPA 13D with PVC piping above.
Over the years this building has had leaking sprinklers. The last two leaks were within a week of each other, one in the second floor laundry room and one in the large lobby sitting area.
The leaks have been found by residents; no waterflow alarms. The sprinkler company who put it in is still doing yearly testing and maintenance. The fire units for these two events found the pressures in the stairwells at 150 psi. The jockey pump turns on at 120 and off at 133.
The sprinkler company says the sprinklers in the PVC piping are leaking at the fitting behind the sprinkler and not the sprinkler itself.
The connection between the sprinkler and the fitting was either cross threaded or over torqued.
Last week I found the gauge on the 6th floor reading 110 psi and the 1st floor at 130 psi.
Can pressures of 150 psi plus at extended periods of time cause the leaking?
The pipe is rated to 175 psi. The building was built in 1989.
And for my own knowledge-the pressure in systems of this type are this high for what reason?
We are told the pressures are typical. Thanks in advance.
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4/28/2023 06:50:06 am
Check the fitting behind the sprinkler. See if it's the same manufacturer as the rest of the cpvc. The '89 installation might have used adjustable drops from a different manufacturer that wasn't as compatible to interconnect as possibly listed or expected.
4/28/2023 07:57:01 am
Well, confirming that these are not sprinklers that have been replaced for the NFPA 25 - 25 Year and upcoming 10 Year requirements for sample removal & testing, the original install may just be at a point where the tape/dope is no longer enough to withstand the irregularities of cross threaded sprinklers or cracking, over-torqued fittings.
4/28/2023 08:15:39 am
You stated the system is using PVC, which is not allowed on a fire sprinkler system. I'm hoping you actually meant Cpvc?
4/28/2023 08:33:22 am
James brings up a good point. Polybutylene was around during that time this system was installed. Is the pipe grey, or is it the typical Blazemaster orange? I do remember there being some quality issues as well on head adapter fittings in the early years of CPVC pipe being installed in sprinkler systems.
4/28/2023 08:48:27 am
Although not quite helpful, I wonder why a 13D system in something other that 1-2 family or manufactured home was allowed unless it was in 1989. A 13R system wouldn't be allowed either.
4/28/2023 09:27:05 am
As mentioned by others, it could be a compatibility issue. I've seen a couple of issues with CPVC and steel pipe. The first one I thought of was the MIC coating that Allied Tube (now out of business) put on their pipe. This was not compatible with most CPVC installs and created leaks on the joints and sealants. That's probably why they're no longer around. The second was when the system was install, it already had some leaks. The fitters used perfumes and peppermint extracts to find the leaks in the newly installed system. When the manufacturers rep sent the fittings in to be tested, it was determined the chemicals in the perfumes created more leaks because of the breakdown of the solvent cement.
4/28/2023 10:19:47 am
The pipe and fittings are likely rated at 175 psi. Over-torquing could be the issue; I’ve seen many develop hairline cracks in the threaded brass insert. There was the time where CPVC fitting manufacturers were coming out with different designs for the reducing coupling – The totally CPVC reducing coupling that I’ve seen crack, and the ones with the metal reinforcement collar. Then the o-ring style that solved a lot of issues. Then some fitters liked to dope-and-tape, others liked to tape-and-dope. Maybe over-dope.
We have had this type of leak occur in CPVC systems regardless of the code application.
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