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NT 201B-A00 04.06 DMX IV Air elimination system e
7.2 CAUSE/SOLUTION/TROUBLESHOOTING
PROCEDURE
Each of the following items describe a single failure
mode. Troubleshoot from high to low probability items.
Before troubleshooting an item, check whether this item
is listed, with the same probability of occurrence, as a
potential cause for another symptom you are not obser-
ving. If yes, place it last in your list of troubleshooting
actions for the given priority and the problem described.
However, when multiple problems occur, troubleshoot
first those items that are listed in each problem trouble
list at the same level of priority.
1/ Air leak on the inlet piping. Check the piping connections.
2/ Vacuum is higher than 4.5" Hg. Reduce the suction
requirements (see the DMX IOM).
3/ Fluid vortexing in the compartment. Install an anti-vor-
tex device at the compartment valve (very rare).
4/ Check and clean the inlet filter strainer (see DMX IOM).
5/ The main float is stuck in the upper position. To check
for this cause, remove the float cover from the DMX
and apply low pressure air to port 1 of the DMX. If
pressure builds up, and the float is not freely moving,
then 5 was involved. Replace the float cover.
6/ The main float is stuck in the lower position. To check
for this cause, remove the float cover from the DMX
and apply low pressure air to port 1 of the DMX. If no
pressure builds up, and the float is not freely moving,
then 6 was involved. Replace the float cover.
7/ Flow detector/check valve installed in the wrong direc-
tion (see Flow Detector IOM).
8/ Flow detector/check valve back pressure is too low.
Increase the back pressure at the check valve. If the
accuracy of this measurement versus the prover is
accurate when not performing a split and stops being
accurate when performing a split, then 8 is the most
probable cause. See the "AIR FREE METERED DELI-
VERING" section of this IOM.
9/ Secondary float sticking in upper position.
Empty the DMX, and open the compartment valve
with the pump not operating. If no air is vented from
the DMX, then 8, 9 or 26 are the most probable cau-
ses. Check 9 first then 26, then 8. See the DMX IOM
for instruction on disassembly.
10/ The DMX secondary float check valve is sticking in the
upper position.
11/ The DMX secondary float check valve is sticking in the
lower position.
12/ The security chamber is full of liquid. Empty the secu-
rity chamber. See 8 above for the troubleshooting pro-
cedure. See the DMX IOM for instructions on chamber
draining.
13/ The air line from the pneumatic cover to the float cover
is blocked. Replace the air line.
14/ Air leak in the line between the DMX and the Pump
relief valve. Repair or replace the line.
15/ Clogged inlet filter/strainer. Clean or replace the
filter/strainer.
16/ The pneumatic cover is damaged. Replace the cover.
17/ Air leak in the line supplying the air to the DMX top
valve. Repair or replace the line.
18/ Top valve seal is locked in the bottom position. Check
to see if the valve between the secondary float cham-
ber and the security safety is open by removing top
security chamber and trying to push the valve with a
smooth piece. If check valve does not move freely,
replace the top DMX valve.
19/ Leakage inside the pump air relief valve. Check the
pump air relief valve for air leakage. Replace it if
necessary.
20/ Pneumatic line from the flow detector to the air control
panel to the DMX is blocked. Clean or replace the line.
21/ Filter at the air inlet on the DMX pneumatic cover is
dirty or clogged. Clean or replace the filter.
22/ Flow detector pneumatic exhaust is clogged. Clean or
replace the exhaust tube.
23/ Low pressure regulator set too high. Adjust to the
lower setting.
24/ Flow detector out of adjustment or out of order. Adjust
or replace the flow detector.
25/ Air leak between the high pressure regulator in the air
control panel and the flow detector. Repair the air leak.
26/ High pressure regulator is set too low. Adjust to a
higher setting.
27/ Insufficient air supply from the truck.
28/ Engine speed control is out of adjustment.
29/ Verify the DMX air/relief valve assembly is installed on
the pump.
30/ Clogging of the line from the DMX to the pump air
relief valve.
31/ Air line from the Flow Detector to the Air Control Panel
clogged. Clean/replace the air line.
32/ Air line from the ACP to the truck accelerator is clog-
ged. Clean/replace air line.
33/ Failure of the pneumatic distributor in the ACP.
34/ Clogging of the line from the Flow detector to the dis-
tributor inside of the ACP. Clean or replace line.
35/ Flow detector part 961 is stuck in the upper position.
36/ Scavenging line is not installed, or clogged.
37/ Irregular pressure delivered from the high pressure
regulator inside the ACP. Check/replace the high pres-
sure regulator.
38/ Irregular pressure delivered from the low pressure
regulator inside the ACP. Check/replace the low pres-
sure regulator.
7. DMX IV Air Elimination System TROUBLESHOOTING
(continued)
