We sell many sizes of vacuum tanks to replace or upgrade your current tank. When dealing with vacuum forming machines using the industry standard “Pump and Tank” systems, make the tank large enough so that there isn’t too much vacuum loss at the end of the forming cycle (large parts are worse). Then make the pump large enough to recharge the tank quickly to a usable level before the next part is ready to form. When evacuating a tank, the pressure will drop very quickly at first, then get real slow at the very end. If your pump is too small, it will never seem to get that last few inches of vacuum that the pump is capable of.