Question
I had my irrigation system replaced on 7/10. The associated bladder tank was deflated while the installation was completed. When the system was turned on the motor ran but no pressure built up in the  bladder tank. It appears that there is no pressure in the bladder tank. What pressure should the bladder tank register to enable the irrigation system to operate?  

Answer
The tank should have 2# less than the start pressure of your pump. Example; If the well starts at 30# then your tank should have 28#. The bad news is, if it is a bladder tank, it wouldn't have lost it's air while the system was off. The air and water are separated by the "bladder". If it lost the air the tank needs replacing.
Reply back with a little more detail of the pump and well situation you have. Also, why you had the system replaced. I'll try to help you better.

Matt