Installer/Operators: Do Automatic Air Vents Leak?

8/26/2024

Can any installers or maintainers provide insights into automatic air vents in fire sprinkler systems?

In your experience, do these vents ever leak water while operating?

Trying to understand why specifications often require these vents to be piped to the exterior. Although manufacturers claim that only air is released, I’m curious if they occasionally sputter or drip water and whether this has caused maintenance issues.

Thanks in advance.

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11 Comments

Anthony

8/26/2024 06:47:57 am

I can answer why specs ask for these to be piped to a "wet ok" area. Generally I'll have these vents located or piped to a janitors closet so when you're purging the air from the system you can allow for some flow of water as more air settles out of the system, similar to a flushing exercise. Also there is nothing an owner hates more than a sprinkler system they didn't want in the first place leaking adding a headache to their lives.

It's a common adage in the insurance world (where my wife works) that the number one claim is fire the number two is water. Often that can mean a sprinkler system that's leaked or a head that's gone off for a non-fire event. So I think that's why the vents are piped to wet ok areas.

Anthony

8/26/2024 08:19:44 am

I'd also add that manufactures claim a lot of things that end up with dubious results "in the field".

8/26/2024 08:09:00 am

Potter has an air vent with a drip pan for water to gather in:

https://www.pottersignal.com/product/datasheet/5401164_PAAR-B.pdf

From the description on the data sheet, it seems like there is a chance water will leak from these:

"Discharge piping from the air vent valve is piped to a shutoff valve
mounted in a water retention pan. The pan retains any inadvertent
water that may discharge during the venting process. If failure of
the air vent occurs, discharged water will reach a specified depth in
the pan (approximately 1”) and a water-soluble fiber element in the
shutoff valve dissolves and closes the valve preventing further water
discharge. The shutoff valve has a visual indication of operation and
a single set of NC contacts rated 24V AC/DC@2A for electronic
supervision (Recommended). The shutoff valve is a single-use device
and contains no user serviceable parts. "

Jim McHugh link

8/26/2024 08:20:23 am

Code does not require the air vent to be piped to the exterior or additional drainage line be added to the vent outlet. There is going to be water molecules in the vented air so you should not locate the vent so that exhausting air blows directly onto a beam or wall where they can accumulate. Installation orientation by the contractor and internal float design which varies by MFG may also impact potential leakage. For more information I recommend visiting www.purgenvent.com

Dan Wilder

8/26/2024 08:21:33 am

There is some moisture that passes by the float valve and can drip (it's a basic mechanical lever & float...air enters, float drops opening the air vent port at the top, float rises as air is expended, air vent port is closed....repeat for new air entering the assembly). It's not a lot but over time can be like any other leak that creates discoloration and damage on whatever is beneath.

Failure of a valve can also create a more continuous leak point (very rare and why some MFG's have a "Dual" vent system).
Many of the MFG's have drip pans available to catch and allow the little bit of moisture in an attempt to naturally evaporate or allow piping to a drain location.

ITM is required regardless and can be as much as quarterly, the MFG instructions request as much. NFPA 25 is visual until the 5th year.

Franck

8/26/2024 09:26:13 am

As indicated above, in normal conditions, there is no "real" water leakage, but mostly moisture being released.
But as water inside sprinkler systems is seldom crystal clear, especially afetr several years, it is wise to avoid rust or deposit stains on ceilings and walls.
In addition, if there is a failure on the system, it usually happens on the weakest point. This is generally on joints and on additional equipments as air vents. So if it happens, it is better to collect the water in a safe place to avoid water damages. All the more since it is in a predictable area and not too difficult to take into consideration.

It would be like installing an Inspector's Test Connection outside a building, but pointing at the parking place of your Manager for his brand new Tesla... Not the best idea, if you can avoid it :)

Dave

8/26/2024 12:17:25 pm

1. Code does not “require” an automatic air vent to be piped to drain. That decision is left to the designer.
2. The threads for an outlet are a requirement of UL & FM in case the designer choses to pipe it to drain.
3. They should not be located above a ceiling primarily (as has been mentioned) because they do exhaust atomized air. And for the same reason should not be placed near a structural element.

The representative further explained why their particular product is designed such that it virtually cannot “spit” but each manufacturer seems to have reasons touting their design, whether it’s the conical shape with float, drip pan, or tandem release valves. It is sometimes difficult to decide which “high point” to choose in installing one, sometimes it’s not a very high point at all which provides the greatest exhausting of air. I balance this with visibility and accessibility. And clearly showing its location on the as-builts and noted in the riser room.

Dave

8/26/2024 12:18:40 pm

^^ The comment above was meant to be prefaced by:
Good question, and responses are spot-on. I have always wondered this but have not heard fitter feedback. I had a long exchange with a rep from one of the manufacturers and a few things he highlighted are:

Jack G

8/26/2024 03:06:27 pm

Great responses all true.
What i found with piping drains is that with a good percentage of the pipe full, or at elbows where water tends to back up, a vacuum is created by the draining water and it keeps the valve from closing properly.
Since the water would have spurts , with the air, I use a nipple with a 6 inch rise and elbow , just after the device, it would allow air behind the draining water, and no vacuum would be created, and only spurts would be drained. A very small quantity of water, because the valve would close properly.

chris

9/4/2024 11:47:15 am

Nobody would have this problem if we still piped the inspectors test at the furthest point of the system and got rid of test and drains.

Jim McHugh link

9/4/2024 12:30:38 pm

Chris,
That does not solve the problem.
NFPA 13 A.8.17.4.2 (2019 and every edition back to 2007) explain that the remote inspector test introduce new oxygen rich air to system increasing corrosion.

Installer/Operators: Do Automatic Air Vents Leak?

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