Section 5: Trouble-Shooting and Repair
MicroBlaster MB1005
Comco Inc.
5-8
Issue Date: September 2003
Hose Failure at the Pinch
During normal operation, the hose pinch will open and close frequently. This
action weakens the hose at the squeeze point and leads to eventual hose failure.
Refer to Section 4 of this manual, “Normal Maintenance”, for detailed information
on reducing this type of failure.
If for some reason the pinch does not close tightly enough to completely seal the
hose, a very slight leak can rapidly wear through the hose and cause it to leak.
Should this occur, the pinch must be examined and the problem corrected. See:
“Inspecting and Repairing the Pinch Valve”, below.
Pinch Tube and Plunger
The pinch tube and plunger are the parts of the pinch assembly that make
contact with the hose. Hoses can sometimes develop leaks at the point where
they are pinched. Leakage of abrasive at these points can cut into the pinch tube
and plunger causing sharp edges that damage hoses. Inspect the pinch tube
and plunger for pitting and sharp edges every time you replace a hose.
Abnormal hose breakage, always at the pinch, is an indication of pinch tube or
plunger damage.
Pinch Tube and Plunger Inspection
1.
Turn off and unplug the MicroBlaster.
2.
Remove the hose from the connector and pull it through the pinch tube
(see replacement procedure, “Abrasive Hose”, above).
3.
Remove the pinch tube. Inspect it for sharp edges or pitting due to
abrasive leakage. Replace if necessary with Comco part number
MB1282.
4.
Inspect the pinch plunger for sharp edges or pitting due to abrasive
leakage. Replace if necessary with Comco part number MB1050-2.
5.
Install the pinch tube. The pinch tube should be hand tightened all the
way on to the cylinder and then backed off about 1/4 turn until the hole is
horizontal.
6.
Install the hose - see procedure, above.
Inspecting and Repairing the Pinch Valve
(refer to Appendix B, Figure 9 and
Figure 10)
Proceed as far as necessary according to the problem.
1.
Turn the Power OFF.
2.
Remove the blue poly hose from the hose fittings and pull through the
pinch tube.
