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Hello,
I'm new to the forum, not sure if this will end up where it needs to go, but here it is anyways, lol.
I am having problems getting even flow at the nozzle. I have a Schidt microvalve II and the blasting will work fine for a bit then no media comes. I chole the pot then it starts puking out sand then will work for a bit. sand is dry and the whole set up is fairly new. Glass bead 50/100 grit with a #5 nozzle, 185crm compressor. Any Ideas?
 

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Hi,

One of my pots has a Thomson Valve and this spits from time to time, in my experience this is caused by the following.

Media with too much moisture content. Your definition of dry may not be the same as your pot actually requires.

Too much moisture in the compressed air. Compressing air requires a huge amount of energy to generate a by product of this is heat and water. Because of the high flow rate required for blasting your water traps need to be slightly open to allow water to escape, you also need to put the compressed air through an air dryer before it reaches the pot otherwise the moisture content in the pot will be too high.

My pot has a valve to adjust air/media mix at the nozzle adjust this to get full flow, maximum media and then turn this back until you can barely see any media coming from the nozzle then you are ready to go.

You may need to strip things apart to clean the pot and valve, I used to do this routinely but now that I know more about the pot I need to do this far less often.

Good luck.
 

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Your pressure in your blast pot and blast hose needs to be equal as well. This gives you a constant gravity feed of abrasive. The blast pot that you have is not a pressure fed pot. When you choke the pot your actually decreasing the line pressure of your blast hose to force the media through your grit valve and into the blast hose in a attempt to clear a obstruction. Also as was stated, your air supply may be wet and your soaking your abrasive in your blast pot. Hot air holds more moisture than cool air so as your air leaves your compressor it is cooling down and thus dropping moisture out of the air. Your dryer needs to be as far away from the compressor as possible. Usually on the air inbound of the blast pot. If your using a cooler then it should be closest to the compressor. If you don't have either one, then moisture would be your problem. Moisture is the number one problem with flowing abrasive with air.

One other thing, make sure that your trying to go too rich with your abrasive mixture. More is not always better. Think Lean.
 
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