Pressure Hold Blast System Basics

Today we’re going to go through the basic principles of how a pressure hold system works.

The pressure hold system starts with our feed air coming in through your bull hose. The air then passes through a small moisture separator to remove any residual moisture left in the system. From there, the feed air comes through and goes down to the pusher line, but it doesn’t go down straight away.

We have the response electric deadman handle. When this is depressed, it sends a signal up through the solenoid into the pilot valve. What happens then is that our feed air passes through the in-line strainer to remove any dust or abrasive in the system before coming through to the pilot valve. This valve is then opened with our return line.

The air then travels through to a T-piece at the bottom of the auto air valve, which opens and sends a signal to our Teravalve at the bottom. This allows the abrasive and the air to mix in the blast hose.

Another thing that is really important when using a pressure hold system is the choke valve. A lot of people like to blast with this partially cracked. What can happen then is that it sends lower pressure air through your pusher line while there is greater pressure air inside your blast pot.

When this happens, it causes excessive wear in your Teravalve at the bottom of your blast pot because the air pressure inside the blast pot is greater than the air pressure inside the pusher line. This forces air and abrasive down through your Teravalve, either causing excessive wear at the top because it will be blasting downward, or wearing out the lower section of your Teravalve much faster than it should.

So remember, if you’re using a pressure hold system, always blast with your choke fully open and in line.