Also buy a new pressure gauge less than 10 and a 14 in. You will need to take into consideration whether you are satisfied with amount of water pressure in the different areas of your home.

Shallow Well Jet Pump On Line Tank Installation
What size well pressure switch do i need. The common settings are either 3050 or 4060. However if the tank pressure has reached the lower cut in setting or better yet if the tank is empty then it is prudent to check the pressure switch. If it isnt make sure your filter isnt clogged or in need of a change. It would typically be about 3 12 revolutions to raise the cut on and cut off by 10 psi. Amtrol remains the industry. The well x trol series by amtrol is the gold standard in well pressure tanks for private well systems.
As water comes out of the tank the pressure of the tank decreases. At this point the pressure switch will turn on and activate the well pump until the tank reaches 50psi. Cut in and cut out psi pounds per square inch of the pressure switch. If you are using a 3050 pressure switch the pressure will continue to drop down until it reaches 30psi. Several other manufacturers have followed suit in including the pre pressurized system in their tank design but amtrol is certainly the first. The pump turns on when the system reaches the low pressure cut in and off when the high pressure cut in.
Switches come in three pressure ranges. 20 to 40 30 to 50 and 40 to 60 psi. Amtrol invented the pre pressurized tank design over 50 years ago as a better solution to the air over tank. By incorporating the diaphragm in the tank itself the problem of waterlogging has essentially been eliminated. If your pump could not develop enough pressure that would be a reason to not raise the pressure. There is a good chance that you could adjust the switch that you have higher.
With the compressor on and the tank pressure well below the normal cut in use the multi meter to see if power is crossing the pressure switch. If you are a homeowner whether you have your pressure switch set at 3050 or 4060 is a matter of personal preference. Check the well tank pressure gauge to see if it is at least 40 psi or the cut off psi for your pressure switch model. That volume of water between 50psi and 30psi is the drawdown. Check the pressure gauge to make sure it isnt stuck or damaged. Pump flow rate in gallons per minute gpm 2.
To determine the proper size of the pressure tank there are three factors to consider. It would be the 38 inch nut in the middle that would get turned clockwise. Desired run time of the pump 3. You do this the same way as outlined above. Always replace your switch with one of the same rating usually printed inside the plastic cover of your old switch.