Window Sprinkler in High-Pressure Application?

6/5/2019

Have a unique scenario I'd be interested in other's take on. Eight-story building with automatic standpipes and a fully-sprinklered building. There's multiple scenarios where the building is close enough to an adjacent building that the exterior wall needed to be rated. In order to keep the fire resistance rating Tyco window sprinklers were installed in conjunction with glass to provide up to a 2-hour fire resistance rating.

The issue is that the sprinkler system experiences a working pressure of up to 220-230 psi, while the window sprinklers are only available as rated up to 175 psi.

We've proposed adding pressure reducing valve to the seven floors affected by this situation, but that introduces its own issues aside from cost. We've also suggested replacing the glass with a rated glass.

Are there other alternatives we haven't explored here? Would be interested in others' opinions.

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8 Comments

FIREPE25

6/5/2019 10:47:39 am

Just out of curiosity, what are your concerns with a pressure reducing valve?

JIM

6/5/2019 11:00:31 am

Pressure reducing valves are more prone to failure than other equipment on fire sprinkler systems. When they fail they often fail in place where no one knows until a full-flow scenario. This is part of why they're required to be tested more frequently.

Part of the concerns with them is the failure, and the second concern is the burden of testing them.

Mike

6/5/2019 11:18:21 am

Where are you getting the idea that they are prone to failure? These are listed devices which means they have been proven to be reliable. Is this project in the MENA?

6/5/2019 11:29:16 am

It's a US Project - and I 100% agree with you that it is a tested and listed piece of equipment so it is absolutely allowed to be designed and installed.

Someone from the risk/insurance sector might be able to answer this better than I could, but I've heard from many people that have had poor experiences with them. I suspect it might not be failure as much as improper settings of the valve itself, but that just hasn't been the feedback I've gathered to date.

6/5/2019 11:19:59 am

There are very few options for other types of fire sprinklers that are rated above 175 psi. I think the PRV is your only option.

Clifford Schulze

6/6/2019 03:12:31 pm

What about using an old fashioned water curtain. Sprinklers installed 6'-0" on center are used at floor openings to provide a fire rating.

Bruce Seiler

6/7/2019 09:55:31 am

An old fashion water curtain is not an approved solution to protect glass. It doesn't "technically" meet the requirements as the entire surface of the glass is not guaranteed to be accomplished unless utilizing a sprinkler head which carries the specific listing.

We have had pretty good luck with the PRV Solution. I agree it is a better solution to utilize a high pressure system, however when the required sprinkler heads are not listed as high pressure, a PRV is required.

The major concern I have is these valves, similar to the a backflow assembly, are not forward flow tested as required by NFPA 25 by many owners or inspectors. We have been on too many projects where this was the case.

Chris Nelson

2/9/2022 08:57:40 am

Hello!

I saw this post and would like to add that reliable just release (as in this month) a high pressure window sprinkler. In case it helps anyone!
https://www.reliablesprinkler.com/files/bulletins/181.pdf?x95623

Window Sprinkler in High-Pressure Application?

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