Water Curtain Sprinklers on Separate Feed?

2/25/2022

I have a project which requires a water curtain be installed on both sides of the glass due to it being the wall down a corridor.

My questions are - (1) does this type coverage require a valve and separate pipe network or can it come off the base building wet system branch lines?

Also, can these same sprinklers be used to cover the corridor as well?

NFPA-13 Section 11.3 doesn't spell this out, so I'm not sure. Thanks in advance.

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11 Comments

Mike L

2/25/2022 07:06:09 am

The closely spaced sprinklers providing the water curtain do not need to be on their own main. They can be connected to branch piping. However, it is recommended to put them on their own branch line to make the hydraulic calculations (balancing) a little easier.

The use of the closely spaced sprinklers for corridor coverage depends on what sprinklers are being used and the arrangement to protect the glass. If using specific window-washer sprinklers or the sprinklers are located beyond the 1" to 12" below deck as of couple of examples, then additional sprinklers are needed.

Alex

2/25/2022 08:45:18 am

I think Mike spelt this out perfectly. The system can be feed off of the floor system but it will make it more challenging when balancing the system. With how advanced design software is now, I would say feed directly off of the floors system.

Depending on the window sprinkler, 100% of the flow is direct at the window. Therefore, anything behind the sprinkler is not protected. If this is the case, additional heads will need to be provided for adequate coverage throughout the corridor.

Travis Mack

2/25/2022 08:08:02 am

Are you needing to provide an alternative to rating the glass? If so, you will need to use the specially listed window sprinklers. They are not cheap. Standard spray sprinklers at 6' on center are not an alternative to using rated glass. You must use the specially listed ones if that is the desired result.

They also have requirements of non operable windows and also no horizontal mullions. There are other requirements you must hit as well. Consult the data sheet for all of the criteria.

They can come off the same system and do not require separate valving. They specially listed sprinklers can not be used to protect floor space. But you must space such that the sprinklers in the adjacent ceiling will not cold solder the sprinklers.

Jesse

2/25/2022 08:09:02 am

Window protection sprinklers do not need to be fed by a separate system. However, the design requirements are different than normal ceiling level sprinklers. Read the listing and equipment data sheet thoroughly. There are some architectural design considerations that are a pre-requisite for protecting glazing this way.

Franck

2/25/2022 08:09:05 am

As indicated by Mike, it is a good practice to have a separate system.
From a reliability standpoint, that way you maintain your fire separation with the water curtain even in case of impairment of the sprinkler system.
It is a good practice to have independent active and passive fire protection systems.

Todd Wyatt

2/25/2022 08:13:06 am

I recommend you review "Windows, Sprinklers, & Fire Ratings" (https://www.meyerfire.com/blog/windows-sprinklers-fire-ratings-part-i) to verify this "deluge" automatic sprinkler system meets the requirements of the applicable IBC edition and if it has been approved by the AHJ.

Glenn Berger

2/25/2022 09:07:51 am

Jumping on the bandwagon - Mike L. nailed it.

Casey Milhorn

2/25/2022 09:24:34 am

As Todd said, check out Meyers blog. I haven't read it yet, but I'm sure he covers everything very well.
The first question I would ask is the coverage for equivalent rating or is it for exposure protection. Two different animals. If for rating purposes, things get very tricky depending on which edition of IBC/IFC is applicable and AHJ specific approval comes into play from my recollection. Some of the gotchas to watch out for: Sprinklers cannot protect operable doors or windows so they need their own rating. They cannot be used as part of a load bearing wall assembly. Protruding horizontal mullions are a no-no. Might be a couple more points I'm missing, but that's the basics. Too many times architects attempt to use this approach to avoid fire rated glazing, and it is used improperly. If you are a sprinkler designer, I would definitely shoot out some RFI's if things appear to be muddy. Also, I believe the newer NFPA standards call for you to calculate these heads ONLY if they fall in or adjacent to your remote area. You could argue by adding these heads, you might have created a new remote area and now you should provide a calculation there. If I were the AHJ, I would want a calc....
Great Question!

Dave

2/25/2022 11:11:48 am

All correct - It gets very complex, and they must be calculated with the adjacent sprinklers. Even the glass itself has to be specific type and thickness, as well as the frames, size of glass (due to limitations of the size of furnace used in testing), combustibles must be heald away from the glass. Along with MeyerFire there are other good resources I keep on hand for each time I have to revisit the topic, including Sprinkler Age https://sprinklerage.com/window-sprinkler-design/ and Reliable's recent webinar from December 2020 https://www.reliablesprinkler.com/resources/webcasts/
https://continuingeducation.bnpmedia.com/courses/tyco/window-sprinklers-as-an-alternative-to-fire-rated-glass/3/
There are variations in listing between the various manufacturers, with concealed versions now available if window design allows.

Jay link

3/2/2022 11:06:43 am

What you're referring to are window sprinklers, not water curtain sprinklers.
Water curtain sprinklers are used around vertical openings that create a "curtain of water" to prevent flames and super heated gases from traveling up the chimney. Most common place you'll see this is around the escalators in a department store.
The IBC (and previously BOCA) requires atriums to be 1 hr fire separated from the rest of the building. In lieu of 1 hr rated glazing, this code allows you to install standard spray sprinklers, on 6 ft centers, 4 to 6 inches off the glass.
Many jurisdictions in my neck-of the woods (Chicago suburbs), right or wrong, have taken this section for atriums, and use it (by amendment) anywhere 1 hr fire separation is required, such as in exit access corridors in office buildings. These standard spray sprinklers are not required to be isolated and they do count towards general protection of the corridor. It all depends on the amended building code of where you're working. The General Services Administration requires atrium sprinklers to be on their own feed with control valve.

Matthew Willis

3/9/2022 09:02:45 am

Just wanted to jump in and add..,

You notice all the responses say "alternate" means. It is crucial to note, adding these do NOT equate to a "Fire Rating".

Also to expound a bit on Jay's response, these systems are copied versions of the original intent.
The very basic ones were used in separating the Manufacturing side of a warehouse from the storage size. (I got to view several of them in my early days as a helper.) There were located at the wall opening where hand trucks, later forklifts drive thru to carry the product from the making side to the stockpiling side.

The atrium version is the one most copied in intent. Now, starting with the 2016 version, we have a Glazing protection section. "Glazing being the recognized term for rated glass.

Those old enough remember the glass with the chicken coop wire in it.

R/
Matt

Water Curtain Sprinklers on Separate Feed?

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