Durabiity of water hammer arrestors?

[Stephen Tashiro]

How durable are the piston type of water hammer arrestors? If there wasn't obvious noise in the plumbing before an arrestor was installed, how can you determine if the arrestor is still working?

Articles on the web say that the type of arrestor that is simply a dead end section of pipe can get filled with water and stop working. To fix the problem ( according to the articles) requires draining the line to admit air. Is there a simpler way to keep air in the dead end?

[Stan Calow]

My understanding is that the air in dead end arrestors can and will eventually get absorbed into the water if that line is left unused for a long enough period of time. I dont think you can fix that without draining the line, without some impractical complicated plumbing changes. I always turn off the house water supply when going out of town so pipes get drained regularly.

I have two of the piston-type (Sioux Chief) arrestors on my washing machine. One (hot) has been fine for several years since installation. The other (cold) I replaced three times in the same time period. I dont know why, but maybe its because the cold gets the most use. Plumber said there should be no difference.

[Lee Schierer]

Water hammer is usually caused by a combination of high pressure and flow with sudden stoppage. It can be cured with slower acting valves, reduced pressure or water hammer arrestors. The old vertical pipe stubs containing air help, but the air gradually gets absorbed. You can install captive air devices for just a bit more money and they last for many years. Here is a pretty good video (https://www.youtube.com/watch?v=QIElso_d2Fc) from a company that is near me. They make really good products.

[Jerome Stanek]

Just put a Schrader valve in the line. You can then add air to the arrestor