What is this fitting for?

[Terry Beck]

What is this, and what does it do? (see pic)

Square chrome fitting, I have seen them before, installed on the main water line coming from a well pressure tank. The nozzle on the side appears to be some sort of an air pressure relief valve, or maybe its used to add pressure to the water line - don't know. Some of the ones I have seen before had a short 5" piece of plastic tubing, but never connected to anything. Note: don't normally see this on newer homes.

Have seen many, but never knew its purpose. The fitting I saw today was sucking air in as we were trying to turn on the water and the pressure tank was trying to fill (the house had been previously been winterized). Could hear a lot of unusual gurgling noises like air in the pressure tank. Once I stuck my finger over the air nozzle, the pressure tank was finally able to fill (though much slower than normal). After that, it stopped sucking air, but started to drip water. In this case, I think something is wrong with either this fitting, or the pressure tank, or both.

Have seen water-logged pressure tanks before, but this didn't act the same way (I was able to bleed some air from the air nozzel on top of the pressure tank; if a pressure tnak is water-logged, you normally see water come out of the tank nozzle instead of air).

Any idea what it is? Don't see any writing on it.

[Lon Henderson]

Interesting. I see a fair number of wells and pressure tanks and I've never seen anything like that. My system doesn't have one either.

[Stephen G]

On a well water filtration systems ie Rust Buster, air is admitted though that hole to allow the particulate to be entrapped in the air water mix and dumped during daily back flushing....it allows a small amount of air in....

[Raymond Wand]

Could have something to do with iron content in well water. If that is the case there should be additional equipment such as settlement tank, and filtration system.

Removing Iron From Domestic Water (http://www.prairiewaternews.ca/back/vol4no1/v41_st7.html)

2.Air Injection Iron Removal This system removes iron without the use of chemicals to backwash. It consists of an aspirator and a bed-type filter containing a special filter media. Different media can be used, depending on the pH and manganese content of the water. The aspirator (small brass venturi device) is installed on the water line between the well and the pressure tank. A Y strainer should be installed in the line before the aspirator, to trap sediment from the well. When the water passes through this device the velocity of the water is increased and air is drawn in to mix with the water. The introduction of the air starts the oxidation of the iron and causes the iron to change into a colloidal form (very small insoluble particles) which the filter removes by attracting the colloidal iron. These filters are backwashed to the drain at regular intervals, which rids it of iron.

[Dom D'Agostino]

Some sort of Air Volume Control valve. Not all wells have them.

[Terry Beck]

Still not sure what it is. Raymond's suggestion might be on the right track. I suspect it is something that was used in the 70's and 80's, but not typically found in newer well systems.

The well for this house does have a LOT of iron in the water. This bleeder check valve, air injection valve, or whatever it is does sit on the incoming water main > before the pressure tank / conttol switch, > and a settlement filter and a culligan iron filter. I have seen quite a few of them before, but obviously not on all wells, and I am pretty sure I have seen them on systems that did not have a water softener or iron filter. I will have to ask my well guy next time I see him.

[Stephen G]

Pleas re read what I wrote...it says 'well water filtration' not exclusively for wells. You can install water filtration on public water if you wanted to...

Culligan Rust Buster is in use today...very common...I have one one my system...and it's only 6 yrs old...



On a well water filtration systems ie Rust Buster...

[Raymond Wand]

Reference
http://www.neotecwater.com/pdf/iron_air_manual.pdf

[Benjamin Thompson]

With non-bladder tanks, there is often an automatic air charging valve that forces the column of water from the pump to inject some air into the tank each time the pump cycles, eliminating the need to recharge the tank with compressed air. This compensates for the air in the tank that gets dissolved in the water. BUT, if this is what this is it will be installed in the main line between the pump and the tank. And they do eventually fail.
They are essentially a check valve with a drain line. Water pumped to the tank is allowed to drain out of the valve (and air enters the pipe) when the pump cycles off. The valve is installed a few feet from the tank so next time the pump cycles on, a few feet of air is injected into the tank.

However, that looks like a bladder tank and that doesn't look like the main line from the pump, so disregard the above...

[Tom Rees]

I think Raymond nailed it. Terry, did you see any type of filter as described in Raymond's link? Is there a high amount of iron in water in your area?

[David Johnston]

It is as Raymond suggests, an air injector to oxidize the iron in the water. There should be additional equipment (filter, settling tank) downstream of it.