"sticky" check valve

[Hube]

Do any of you "pro's" know what causes a checkvalve to make a 'thump-wham' sound when the pump comes on.
This is a check valve located near the pressure tank that is supplied by a sub pump in a deep well.
It's a 1" brass check valve, it operates quietly for a few months ,but eventually upon activation it has a quick 'thump/wham' sound upon opening.

This makes the whole supply line move slightly for a second. It does open and the system is operating fine. It's just this noise that it makes has me concerned as to any damage it may cause.
I have replaced this valve 3 times in the last 3 years. When a new one is installed it works smoothly for a few months and then starts to make this thump/wham.
What can cause this, and are there any "silent type of check valves that will not stick?

My theory is that the water from the Well, being slightly hard, causes a chemical reaction to the valve's seat (poppet)and so to speak creates a "weld" or sticking effect, and temporarily delays the opening of the valve.
What do you think?
Thanks for any reply

[Mike Swearingen]

I think that you're right.
Sounds like hard minerals in the water (calcium and magnesium) are building up inside the check valve, and are temporarily holding the check partially closed until it "releases" back against the spring causing the thump-wham.
If the mineral build-up is that fast inside the check, the only thing that you can do is to take it off-line and soak it in vinegar overnight to dissolve the minerals, and/or replace it. You might even alternate two checks, if this is becoming a real problem.
Good Luck!
Mike

[Hube]

Mike; thanks for your reply.

And yes, I believe there is a bit of magnesium,etc in the water.

I have heard of a "silent" or " non-slam type of checkvalve. Its supposed to have a valve/ seat made of Neoprene or other material and is not effected by these chemical elements that are in the Well water.

I have searched the web and have found there is a 'silent type check valve out there, but only in 3" or larger.