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Blow-By And Chugging Issues With TeraValves And Thompson 2 Valves

Today we’re going to talk about a common wear item on the Axxiom Schmidt Tera Valve, that also applies to the Thompson II metering valve.

Are you guys experiencing Blow-By at the end of your blast hose or notice it chugging sand when you first fire up the dead man handle?

Nine times out of ten, the culprit is a urethane seat in the bottom of your metering valve.

Blow-By can be defined as air creeping out of the end of the blast nozzle while the operator is not using it or on the dead man handle. The urethane seat does not seal the piston and this allows abrasive and air to leak into the blast hose while the operator is not activating it.

Therefore, when you lift the hose up and fire it up, it has to clean all the abrasive out of the hose that was leaked into it before the pressure driven media starts to float normally. That’s the cause of the chugging.

And, as mentioned, if you’re using a TeraValve or Thompson II, nine times out of ten the culprit is your urethane seat in the bottom of your metering valve.


Three of the most common reasons that this occurs is due to either

  • moisture in the pot and the operator having to choke the pot constantly
  • excessive dust in the abrasive or also
  • differential pressure

All three of these issues can be corrected just by dropping the metering valve, removing the base, and replacing the urethane seat. Typically, this process takes anywhere between ten and 15 minutes.

At the end of the day, this quick, easy fix is going to save you in the long run.

  • It’ll create less wear on the base of the metering valve.
  • It’ll reduce abrasive consumption.
  • And it also makes it a safer environment for your operators to work in.


How to Maintain, Repair, and Install a Schmidt TeraValve Rebuild Kit


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