Using the correct procedure to pressurize and depressurize the system is very important. It will prevent media and water from flowing backwards through the system, which can cause other parts to fail.
Once you have the water and abrasive in the blast pot, and your compressor is on, follow these steps to pressurize the pot.
Air always flows in the path of least resistance. If you turn the compressor off first (or switch it to unload on some models) the pressure in the pot is trying its best to get out. Air, media and water can go up the black air hose in the wrong direction. That debris could potentially go through the regulator and end up in the small filter regulator, causing your Parker valve to fail.
If your Parker valve needs maintenance, check out the article here.
If you need to buy replacements, check out the following from our online store:
Following proper procedures will prevent glass from entering the small filter regulator on the control box, and/or blast pressure regulators failing.
Example of glass in filter regulator on control box: