I don't know if this is the right section for this but here goes,
I have an 8 HP two stage air compressor with a 100 gallon tank in my shop. It is about 4 years old and about a month ago I started noticing an echo coming from the tank every time I fire a nailer/stapler.
About three months ago I added a new line regulator but I don't know if that is causing it since the noise didn't become apparent until two months after it was installed. I drain the tank often and generally try to maintain it by the book.
The sound sounds like someone lightly tapping on the tank with a ball peen hammer when a nail gun is fired. Any ideas?