Diaphragm Well Tank pressure
I recently purchased a farm with a well. I would like to verify and adjust the pressure on the Challenger (Flexon Industries) 33.4 gallon, model PC122R diaphragm well tank. It has a yellow sticker on top that says 38psi. Under that someone wrote with a sharpie LRPS 3-19-04. There is a automobile style valve on the top with a cap on it.
Is it as simple as inflating a tire? Does the tank need to be full or empty of water during the process of verifying and adjusting the pressure?