Air Chamber, What function does this serve?

[M Barnes]

Forgive my ignorance. What function does this long, capped, vertical copper tube serve that branches out from below the water shutoff valve on 1/2" pipe? What is it called?

 

[Terry]

Old school air chamber for water hammer. They become filled with water and no longer work as desired after awhile.
We now use hammer arrestors for the dishwasher, ice make and the clothes washer.

This have a piston inside.

 

[Sponsor]

 

[M Barnes]

Thanks, I appreciate the reply!

 

[Tuttles Revenge]

Theres a diagram in the Illustrated UPC that shows the air chamber and why they think it loses air basically by cycling air and water in and out of the chamber, the air is replaced by water. I think that the air is simply absorbed by the water under pressure.

 

[Jadnashua]

An air chamber can tend to work for a few months, then tends to become saturated, and just stagnant water. Before we had all of the synthetic rubber and silicone materials, that was the best they could do. SHutting the water off, they don't always drain, just like when you put your finger over the end of a straw.

 

[Jeff H Young]

Don't know if in later UPC code books it has the sizes needed for air chambers in lieu of hammer arrestors. Or if they are still permitted in lieu of a arrestor?
Code requires them but I hardly see a need (hammer arrestor) on a well plumbed home . it is an once of prevention though. I think 10 dollars more worth of strapping would be twice the value of an arrestor

 

[Jadnashua]

Solenoid valves can cause some pretty significant shock waves in pipes, so a hammer arrester isn't a bad idea. Some shower valve designs specify one with their installation, but it's not common in that situation. SOme toilet fill valves can be pretty abrupt. So, the issue is two-fold...the actual shock waves in the system, and poorly installed pipes that end up moving, literally hammering on some surface. You can help resolve the latter, but the former will always occur on a fast-acting valves.

 

[Terry]

A friend of mine used to be woken up several times during the night when the ice maker finished filling the trays.
I gave him a hammer arrestor to fix that. He slept better after that.