Automatic Fire Suppression System Question
 

I’ve got an automatic fire suppression system in my garage. It was originally installed in 2003.

The pressure reducing valve (PRV) is required to be set at 100 minimum for this system.

Everything worked well from 2003 to 2011 when I noticed the system pressure was too high. I replaced the pressure reducing valve with the same unit, a Wilkins/Zurn 600XLHR. Designed to accommodate up to 300 inlet PSI, factory set at 85 PSI (adjustable from 75-125 PSI). It is important to note this PRV has a direct acting integral by-pass design prevents buildup of excessive system pressure caused by thermal expansion, typically from a water heater.

Recently I noticed the pressure had raised to 150 PSI and suspected the PRV had failed again after 12 years of service.

I replaced the PRV with the same model as the two before. Here is where the trouble began. After I installed the new PRV I adjusted the pressure to the recommended 100 PSI. The pressure held constant until the next day when it had risen to 150 PSI. I released the pressure in the system, then turned the water back on, adjusted the pressure down to 75 PSI and within a day (late afternoon) the pressure had risen to 150 PSI again.

I removed the newly installed PRV and exchanged it for a new unit (same model.) I reinstalled it but did not adjust the pressure, leaving it at the factory setting of 85 PSI.

Overnight the pressure held at 85 PSI. However, by 2:00 pm the next day the pressure had risen to 115 PSI.

I opened the main drain for 1 minute, purging the system. Once I closed the main drain the pressure stood at the factory setting of 85 PSI.

Does anyone have any idea what is going on? It is not particularly warm now, and I have not done anything to the system other than change out the PRVs.

Could the back flow preventer be the source of the problem? It is 19 years old. (Black Arrow in photo)

The system doesn’t have an expansion tank. Is there a PSI pressure that will activate the system?
http://forums.pelicanparts.com/uploa...1651613899.jpg


Factory set at 85 PSI
http://forums.pelicanparts.com/uploa...1651613985.jpg

Is that CO2 or another inert gas?
Over time there may be some chemical reaction in the system which might raise pressure. Just a guess.

There used to be haylon fire extinguishers, but they've been banned afaik.

No it is a water system. Sorry I used Pressurized/depressurized implying gas.

The sprinkler heads are called “frangible bulbs.”

At 155 degrees F the bulb bursts and allows water to flow. I’m wondering if there is an internal pressure that will break the bulb and set off the system in error.

http://forums.pelicanparts.com/uploa...1651619353.jpg

Is that system plumbed right into your regular house water? City water or well? The pressure is high. Even systems on a fire pump only run on the 70-80 range

I've never seen a sprinkler head activated from over pressurization. ( not saying it never happens,...) most

Just on a side note, you should change the heads every 5 yrs or so...

Our system at work shows the max city water pressure which goes over 100psi regularly.

I am hooked up to city water, pressure from the street is 150 PSI

The inspector wouldn’t sign off on the installation until we put this sign by the PRV

FIRE SPRINKLER PRV
Do Not Adjust
Must Be 100 PSI Min

I did some research and saw this model of sprinkler head is rated at 175 PSI, so I may be OK at 150. It bothers me that this system can’t maintain the set PSI of 85. MAYBE there is air in the line and that might be affecting the pressure.

I opened the main drain again for 45 seconds, let’s see what happens in the next day.

150psi from the street??
Holy crap that's impressive! I wouldn't even have to run my pumpers! We are lucky to get 80 out of our hydrants here in NJ.

.

Yea. . . I’ve got several Zurn 600XL pressure reducers (300 PSI max in/ 50-75 out). The one for the fire system is a 600XLHR (300 PSI max in/ 75-125 out).

I’ve got one outside faucet running the 150 PSI, works like a pressure washer.

We are at the end of a water distribution line, and the area keeps building new homes and businesses. When we first moved in we were lucky to have 40 PSI at off peak times. In the mornings when lots of people were taking showers it got really bad. Finally the city put in new water mains and wee finally have respectable pressure, but nothing close to 100 PSI.

40 PSI !!??

Looks like I have a good problem.

UPDATE:

I sent an email to the company that makes the frangible bulbs. Here was their response. . .

The gem F680 is UL listed for a maximum pressure of 175psi. Not Maintaining your designed system pressure will affect your system operating correctly.

So at 150 PSI it would appear the system likely will not inadvertently go off.

Gives me a little breathing room to figure out the 150 PSI issue.

Check MAX pressure on your toilet valves. That is a lot of water pressure.

Automatic Fire Suppression System Question
 

A new install is typically tested to 200psi for 2 hours or 50psi over working pressure if the working pressure is in excess of 150psi.

I would worry about the heads, I’m sure there’s a safety factor built into that 175psi max.

Have you called zurn?

EDIT: Out of curiosity, I pulled up the specs and they recommend multiple PRV where the desired reduction is 4 to 1. That’s not your requirement but they also state that you’re not to bottom out the adjustment.

I wonder if a second PRV in series wouldn’t solve your issue.

A second PRV may be it.

I’ve noticed the pressure creeps up in the afternoon. I may put in a 125 PSI pressure relief valve on the system and see if that helps keep things in a more desired range.

Option 2 is see if I can put an expansion tank in the system.

I have not called Zurn . . . yet

I looked it up . . . here is the regulation of anyone is interested


Per NFPA 25 Sec : 5.3.1.1.1.3* Sprinklers manufactured using fast-response elements that have been installed for 20 years shall be replaced or representative samples shall be tested and then retested at 10-year intervals.

We got a notice from the county they were going to come in and do a safety inspection, because the pressure we are getting from the water district is not high enough to assure the fire suppression sprinkler systems work correctly. They charged me $150, and told me I could not have a deadbolt on any of exterior doors in my office.

There are no sprinklers in this building. I am not comfortable have dead bolt free doors on my office. As a matter of fact, I am almost certain that medicare requires that I have deadbolts securing where I store medical records. Pretty much no matter what I do, I am guilty of a violation

Just thinking out loud,
you quoted the minimum when the maximum is your concern
confused me too, maybe it takes 100 just to operable?dunno
150 from the street has me wondering, how high does that water have to push upstream of you, awesome problem to have .
should you increase the size of the feeder pipe to increase flow while increasing pressure(did i do that backwards?)
I guess Jersey did Legalize weed, have a Great Day

Minimum pressure to be effective is 100 PSI

I’ve got that no problem.

The Frangible Bulbs will activate the system at 155 degrees F. They are designed for 175 PSI max with a room for error of an additional 50 PSI

Ideally I want to keep the pressure at 125.

I’m going to experiment with a pressure relief valve set at 125 PSI.

To be honest, the system may have been operating at 150 PSI for the last 20 years. . . I may not have noticed until now.

and that is cool

I take it this was installed because of building codes?

Is it still required? Can you delete and cap it off?