When we turn on the valve for the cold water a burst of air comes out and slashes you. The hot water valve works fine. After the burst the water flows fine,but if you shut the valve and leave it off for 20 minutes or more the air pressure is back with a burst. This is a problem that has been going on for year in our company break room. I am wondering if anyone has encountered such a problem,more so how to correct the problem. Any help would greatly appreciated.

Thanks Scubafool

It is weird, maybe from supply, as long as pressure is ON, water usually leaks out, and air doesn't leak in ?

Yes it's weird but I still not sure how to correct this problem.?

I would maybe try opening each faucet until air is out? Do you shut off the main supply, often, or at all. Air may get in line during thost times.