I getting ready to install this Thompson Valve with an air media shut off switch. I am going to put the ball valve near my nozzle. When I turn it, the media shuts off immediately clearing the blast hose but still blowing air. Blow down will be when I release the dead man. Here is a pic of the valve. Notice the air inlet hole on the side.

I've been doing this for year's Dyer and have never had a issue. Don't see how it could overide the air to the remote. Here is a picture of my set-up. From where my 1/4" line goes to my valve I installed a 1/4" ball valve going to each Grit Valve. Like I said, I have done this for years and never a problem and this is the first I have heard of it happening.

No troubles with my Tek pot. It works flawlessly. Thanks for checking though "saftey first"

Benny, I thought todd was nuts when he said he was having problems, but yesterday it hapened to me. I stopped to blow down and as soon as I turned of the air to the meter valve off, the nozzle started to blow air.??

turn the air back on to the valve, it would stop.
I sat of over 30 mins, turning on and off and every time it failed.
Its a normally closed valve. and with the air off to it should stay shut. but some how the back psi is turning it on.
Todd and I both have new pots so wair and tear is not an issue?

Your set up is just like the one I used for over 10 years, This has me stumpped.

I would chalk it up to cold weather, but todd is in florada and it happened to him?

Benny, do you have a pressure regulater before the lines?

painter213 said:

I've been doing this for year's Dyer and have never had a issue. Don't see how it could overide the air to the remote. Here is a picture of my set-up. From where my 1/4" line goes to my valve I installed a 1/4" ball valve going to each Grit Valve. Like I said, I have done this for years and never a problem and this is the first I have heard of it happening.

Click to expand...

Nope. Don't use a pressure Reg. Is your remotes Elec. or Pneumatic? I still don't see how it can activate the valve to open. Your just stopping the air from activating the plunger in the Thompson valve is all. Let me think about this somemore. I have to get to work now so I will mull it over some while I'm in the NUCLEAR REACTOR tonight. That will give me something to do.

12 v trigger, with gatekeeper and Thompson valve
It’s the same set up you got but on a single run.

The Thompson valve is a failsafe, normally closed valve.
As is the gate keeper?

Leads me to think the 12v module is somehow failing because of back psi?

The pot has a flow valve just before the 12v mod. Maybe a psi regulator would be better to stop it from over pressurizing?

That would not be it "over pressurizing". I have used up to 150psi with no problems. I just cannot see anyway that stopping the airflow to the Thompson valve would do this. Something is making your Normally Closed Valve open. I just cannot put my finger on it though. I've been doing this to Canned Sands for over 12 years and have never run into this. Even when your pot is stopped there is no air pressure on the 1/4" line going to the Thompson Valve. The big spring holds the pressure to the piston in the stopped position. All the air does going to the valve is opens it up to start the flow of abrasive. I'm still thinking on this one man.

thanks Benny, It has me stumped too.
I'm making some calls to old friends at the ship yard to see if they've come across this at some point.

Once again Thank you for your input.

Paul if you are on, any Idea's on this?

Dyer;

Have you resolved this problem? I talked to someone at the PACE show about it and they have no clue as to what would make the pot turn on when you close the 1/4" ball valve. For some reason I thought you had a Axxiom pot, but it does not matter. Marco just copied the Axxiom so they are all the same. If you want to talk to the man that I talked to, give me a e-mail and I will send you his name and number. He is the V.P. of Production.

Thanks Benny, I still have been messin' around with this.

The thing is it not just my pot, todds does the same thing to. he is the one that brought it to my atention, then days latter mine did it.????

I'm going to try a small relief hole just under thr 1/4 ball valve like kill did. I think there might be a small amount of traped air still in the valve?

I'll see if this works... let you know

Found the reason...

In one of my books from Marco,
The Right way to have the Abrasive Cut-off switch is shown in the back
with a 3 way shut off,

3 way.. when shut off, it releases the air from the mixing valve...

WTF.. :wallbash: I've been beating my head off the wall on this one for months, happen to look in the wrong spot for something else...

Posted the schematic for you to see!

Jim, did you ever make this change to your pot?...I just had a major failure to my mixing valve(maxxum) and had to replace it completely and a new air solenoid...

No Todd I didn't. T took out the 1/4" ball valve and just turn down the grit by hand.

although, there is a 3 way vave that you can buy. as you shut it off, it drains the air from the mixing side. releasing the air out of the canister. apparentley the can will keep a bit of psi when shut off.

I talked to marco at some time on this.. sorry I didnt repost the fix...

I've had to replace the plastic sleave in the mixier at one time, so I just rebuilt it.

I've been finding out though that taking off the big round end that has the orange knob, and useing white lithem greese alowws the plunger to move with out squeeking...

what happend to your valve???

blastserv said:

Jim, did you ever make this change to your pot?...I just had a major failure to my mixing valve(maxxum) and had to replace it completely and a new air solenoid...

Click to expand...

Long story...short

Marco claims my exhaust was dirty and therefore creating back pressure on the system when I am shutting down and bleeding air off of the pot and the back pressure is dusty air which goes up into the solenoid trashing it and then down to the air side of the maxxum valve also trashing the cylinder wall...I purchased a new piston and housing which is essentially the cast body that is the valve...when I rebuild the whole thing I ddint realize there is a v seal under the tungsten sleeve (where you mentioned yours is urethane) and when I went back to take it all apart the cap that the media adjustment knob screws into galled the threads and ruined the new housing...

Now I haVe lots of spare parts!

They claim I should extend the muffler down with a longer pipe almost to the floor to give it more expansion room...sounds like a silly fix but I'll try it...

Love my Marco pot though...that thing has almost no wear
on the tungsten sleeve and plunger...I'd buy another!

"Love my Marco pot though...that thing has almost no ware on the tungsten sleeve and plunger...I'd buy another"

I agree Todd, I love mine to.

I rebilt my whole thing to, but really only need to do the insert..
I've got extra parts too. but might need them some day?

I broke my silinoid off in the first year of loading it it to my truck, had to by another 12v one... but placed it into a metal electrical box and have had no problems sence.


I had a chance to put mine up against a clemco about the same size.
the differance was thiers didn't hold the psi in the tank, it drained every time they released the air trigger. (and little experience too.) but they filled there tank twice to my one time. every time they stoped and started it chugged grit, waisting it... :thumbsup:
made me feel good about our set up.

I am going to order the valve...let you know once I have it in use how it is going...