A: No air or abrasive passes through the nozzle:
1) Check that the compressor air is fully turned on..... many road compressors have a seperate air release valve button.
2) Check that the rubber insert on the deadman handle has not been lost. Replace if necessary. 3) Check the deadman handle head is not blocked .... is air coming out of bleed hole ? If yes, remove the yellow return hose, depress handle, and check air is coming through.
4) Check the water separator is not blocked. Clean if necessary.
5) Remote control valve is not working. Check that the mini ball valve / machine stop is in the closed
position. Check exhaust silencer, and exhaust side of valve is not blocked ..... change diaphragms, pistons, etc., if necessary.
6) Check the remote control / twin lines for loose connections or leaks.
7) Foreign objects blocking the nozzle. Remove and check but beware there may be build up of pressure in
the blast hose. Depressurise total system before checking.
B: Air but no abrasive passes through the nozzle.
1) Check that the abrasive metering valve is open.
2) Damp or large objects restricting flow at the base of the cone. Quickly close and open the choke valve. If
this fails clean out the inside of the vessel. 3) Check for air leaks from the pop-up assembly, hand hole or other area causing the pressure above the
metering valve tee to be lower than the pressure below which prevents the abrasive falling through the
C: Intermittent Flow of Abrasive , Constant on/off cycle
1) Faults as for B:
2) Abrasive valve not set correctly
3) Inspect Uniflo remote valve …. Remove cover (4 bolts) , and check piston and pad for wear, check rubber
diaphragm for splits.
4) Machine supplied by very damp compressed air. 5) Too much air going into the deadman handle .... check the male nipple on the handle inlet hasn't been drilled/enlarged .... this can lead to the deadman air bleed hole being bypassed, as it is unable to cope with the inreased volume of air. 6) Blast nozzle worn out / too big. 7) Blast hose worn out / too big
D: Abrasive Surges from the Nozzle.
1) Abrasive metering valve set too far open. Close gradually until the correct setting reached.
2) Choke ball valve is not fully open. Ensure the handle is set in the same direction as the valve/ flow of the air.
E: Pop-up valve will not remain seated against the sealing ‘O’ ring:
1) Insufficient volume of pressure of air. Check that the air supply is sufficient for the nozzle used. Check
compressor is operating correctly.
2) Close the choke valve, if the pop-up valve then seals then insufficient air is available.
3) Check condition of filter in water separator for blockages.
4) Check operation of remote valve 5) Too much air going into the deadman handle .... check the male nipple on the handle inlet hasn't been drilled/enlarged .... this can lead to the deadman air bleed hole being bypassed, as it is unable to cope with the increased volume of air. . 6) Blast nozzle, and/or blast hose, worn out or too large.
F: Pop-up valve will not drop after depressurisation.
1) The pop-up valve and/ or sealing ring may be worn. Inspect and replace if necessary.
2) Abrasive trapped in vertical pipe work. Strip and clean out.
3) Silencer system not working. Exhaust port of remote valve, pipework, or silencer may be blocked with abrasive. Strip and clean all, renew silencer core if
G: Machine will not depressurise.
1) Check for blockages in deadmans handle or lines. 2) Check for blockage in grit valve, blast hose, and blast nozzle
3) If it still does not depressurise or turn off after opening the petcock/ machine stop on the remote control
valve, remove and repair the remote control valve.