Abrasive in the Control Valve

I am not sure who at Axxiom looks into these issues, but we regularly have instances of abrasive getting past the dust eliminator and into the control valve/ deadman. Even on very new (less than 2 weeks old) equipment.
Usually it is from abrasive coming backwards through the pop-up piping, or fine recycled abrasive, and we do have some answers for that.
Is there a solution, or a better product for this important dust capture function?

ABRASIVE IN THE CONTROL VALVE:

NORMALLY CAUSED BY BACK FLOW THAT IS A RESULT OF ONE OR MORE OF THE FOLLOWING MOST COMMON OCCURANCES:

1. TURNING OFF THE COMPRESSOR: DO NOT TURN THE COMPRESSOR OFF WHILE THE BLASTER IS UNDER PRESSURE. DOING SO WILL ALLOW THE VESSLE TO DEPRESSURIZE THROUGH THE AIR SUPPLY HOSE.
2. THE COMPRESSOR IS NOT DEDICATED TO THE BLASTER: DURING PEAK USES DURING THE DAY WHEN OTHER AIR TOOLS ARE BEING USED, THE COMPRESSOR IS NOT LARGE ENOUGH TO HANDLE THE ADDITIONAL DEMAND OF CFM CREATING A DROP IN THE SUPPLY AIR AND BACKWARD FLOW OF AIR FROM VESSEL.
3. IN THE CASE WHEN A LARGE NOZZLE (#8 +) OR MULTIPLE NOZZLES/OUTLETS ARE BEING USED: WITH A MARGINALLY SIZED COMPRESSOR, WHEN THE DEADMAN IS DEPRESSED, THE COMPRESSOR WILL DROP FOR A COUPLE OF SECONDS UNTIL IT BUILDS MOMENTUM BACK UP AND EQUALIZES THE PRESSURE. DURING THAT MOMENT OF DROP IN SUPPLY AIR COULD ALSO CONTRIBUTE TO DUST MIGRATION BACK INTO THE CONTROL LINES.
4. THE QUESTION OF "ABRASIVE GETTING PAST THE DUST ELIMINATOR AND INTO THE CONTROL VALVE/DEADMAN": WE BELIEVE THAT IT IS STILL MIGRATING FROM BACK FLOW AND TRAVELING THOUGH THE STRAINER VIA CONTAMINATED CONTROL HOSES RATHER THAN THE DUST ELIMINATOR. PLEASE REMEMBER TO CLEAN ALL CONTROL HOSES BY DETACHING AND BLOWING THEM OUT AFTER YOUR BACK FLOW ISSUES HAVE BEEN ADDRESSED. ONCE THE HOSES ARE CONTAMINATED, DUST AND ABRASIVE WILL REMAIN TRAPPED IN THE HOSES THAT WILL PASS THROUGH THE CONTROL VALVE UNLESS THEY ARE CLEARED.
5. POP UP ADJUSTMENT: THERE ALSO HAVE BEEN SOME CASES WHERE THE INTERNAL VERTICAL PIPE HOLDING THE POP UP WITH STEM INTO PLACE HAS BEEN REPLACED OR CUT SHORTER WITH THE BELIEF THAT THE VESSEL REFILLS QUICKER CREATING A LARGER GAP BETWEEN THE GASKET AND POP UP HEAD WHICH IS NOT THE CASE. THERE SHOULD ONLY BE A GAP BETWEEN 0.625" AND 0.840" BETWEEN THE POP UP HEAD AND GASKET. REFER TO SECTION 5.1 OF THE ABRASIVE BLASTERS OWNERS MANUAL. IF THE POP HEAD IS TOO LOW, WHEN THE VESSEL IS UNDER PRESSURE, THE DISTANCE BETWEEN THE POP HEAD AND VERTICAL PIPE IS TOO GREAT THAT CAN ALLOW MATERIAL TO FALL INTO THE PIPE MIGRATING BACK TO THE CONTROL LINES.

SOLUTIONS:

1. DEDICATED COMPRESSOR: PROPERLY SIZED DEDICATED COMPRESSOR FOR THE BLASTER. ENSURE AIR HOSE TO SUPPLY BLASTER IS LARGE ID TO ACCOMDATE NOZZLE SIZE. REFER TO THE AXXIOM BLASTING DATA SECTION 13 OF THE ABRASIVE BLASTERS MANUAL FOR PROPER CFM AND HOSE REQUIREMENTS.
2. REDUCE OR REPLACE WORN NOZZLE: IF # 1 IS NOT AN OPTION.
3. CLEAR CONTAMINATED CONTROL HOSES/TWINLINES: IT MAY BE NECESSARY TO REPLACE HOSES AS NECESSARY.
3. IN SITUATIONS AS SUGGESTED IN NUMBER 3: AXXIOM HAS DEVELOPED A PATENT PENDING DEVICE CALLED A GRIT SUPRESSION VALVE (GSV): THE GSV IS DESIGNED TO SLOW THE BACKFLOW PRESSURE DOWN WHILE STILL ALLOWING THE VESSEL PRESSURE TO EQUALIZE. SLOWING THE BACK FLOW PREVENTS THE MAJORITY OF DUST PARTICLES BEING CARRIED. IT IS EASILY INTALLED BETWEEN THE INTERNAL VERTICAL PIPE HOLDING THE POP UP WITH STEM AND THE 90 DEGREE FITTING.

Axxiom Sales Staff
1.800.231.2085
Fresno, TX

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