Question about pressure tanks?

I was looking at an extra pressure tank that I have and noticed some kind of black valve or something at the outlet.

Is this a valve that closes when there is no water in the tank? Do all tanks have these?

The reason for my question is...the tank I installed was sitting outside a few days before I installed it and I was wondering if a mouse or a cricket or something could have got it the tank. We are experiencing some water odors.

More concerned about a mouse...the cricket probably wouldn't be a problem.

I could be wrong, but I believe what you are seeing there is the internal bladder ... and if you release the pressure, it will probably pull back from the end of the tank.

The tank is probably precharged with air. If you release the air you will have to precharge it with a compressor.

You should decide what your pressure switch will be set at, and the air pressure should be set at 2 psi less than the lowest START setting of the pressure switch. You can do that after the tank is installed.

You need to be sure that the air pressure is lower than the switch START setting or you will have a brief NO PRESSURE event every time just before the pump starts.

Have you got a picture you can upload here?

bob...