Steps to troubleshoot a 6.5 Blast Pot




Let's walk through the most common issues affecting a pressure hold blast pot with a Thompson Valve. Here we cover the solenoid, auto air valve, and Thompson Valve.


Check first - The Solenoid

When troubleshooting a blast pot, the first place your should start is the Solenoid. The Solenoid controls air supply, abrasive supply and everything else relating to the pot.

How it works: Air supply comes in from the inlet, supplies through the brass strainer which cleans the air, goes to the solenoid as well as the first lead of the twin lines. From the first lead of the twin lines it goes to the deadman handle and returns back, once the trigger is activated, to the return. When the return is activated, it moves the piston over which allows air to flow through the solenoid. The solenoid then supplies the auto air valve as well as the Thompson valve.

Issue indicators:

  • The blast nozzle being stuck open
  • No abrasive being released — only air getting through to the nozzle


  1. Is the solenoid working? When you activate and release the deadman handle you should feel a puff of air coming through the muffler on the back side. This indicates if the valve is opening and closing successfully.
  2. Take off the 'air out' line from the solenoid, which will not allow the auto air valve of the Thompson valve to open. This will allow only the solenoid to actuate which makes it safe to perform in the field. By taking this line off, no air should be coming out of the outlet. When you activate your deadman handle, air should come back through the return, it should open up the valve and allow air to come out of the outside of the solenoid.
    1. If this happens, it indicates that the solenoid is working correctly.
    2. If air does not come out of the solenoid, the first component you should check is the deadman handle. Take off either the supply or return and test the handle independently. if this is working correctly, there may be debris inside the solenoide which is built up and resulting in it not being able to move.

Solution: If debris in the solenoid is determined, remove the 4 screws and pull the internals out of the solenoid, clean it out and replace the o-rings as required, or purchase an Axxiom replacement kit.


Check second - The Auto Air Valve

If the solenoid is working correctly, the next component of the blast pot to check is the auto air valve.

Issue indicators:

  • Blow-by air out of the nozzle
  • No air at all in the blast stream, only abrasive
  • Hose chugging


  1. If you lay the blast hose on the ground, the operator isn't blasting and trigger is not engaged, and there is still blow-by air coming out of the nozzle you'll need to check the auto air valve. Do this by simply turning the choke valve from the 'on' position to the 'off' position.
    1. If the air stops, this indicates and issue with the auto air valve.
    2. If the air doesn't stop, continue to check other components of the auto air valve before moving on to the metering valve

Solution: If you do determine the auto air valve is the issue, it will need to be replaced. It is an indication that it is preparing to fail and may cause issue when out in the field.


Check last - The Thompson Valve

If the solenoid and auto air valve are working correctly, the next component of the blast pot to check is the metering valve.

Issue indicators:

  • Blast nozzle keeps blasting/chugging only abrasive (no air) when the deadman is activated
  • After the blat hose have been unused for a minute or two it chuggs out abrasive abrasive when blasting restarts
  • Blow-by air is escaping


  1. Shut off the inlet (gate) valve of the Thompson valve. This shuts down the abrasive supply to the Thompson valve. If air stops escaping from the blast nozzle, this indicates that there is an issue with the Thompson valve.

Solution: If the Thompson valve is filling your hose with abrasive or it's never shutting down, this could mean that it is stuck open and should be taken apart and inspected.



These trouble shooting tips should help out on the field and when assistance is not available. You can always give BlastOne a call and our technical team can talk you through a solution.


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