T M 1 0 - 4 6 1 0 - 2 3 2 - 1 2
Table 4-2. Unit Troubleshooting Guide (Continued)
TEST OR INSPECTION
Shut down the ROWPU. Drain water out of the media filter until all the flags on the level assembly are
white, or until water does not come out of the media filter top drain valve. Restart the ROWPU. en
the media filter vent valve and leave open until water is flowing steadily out of it. Watch that all the flags
turn red on the level assembly as the filter fills with water.
If the flags do not turn red it indicates the float is sticking. Refer to level assembly sticking trouble-
Check that when the ROWPU is operating and the level assembly flags have turned red to the top, that
the air blanket solenoid valve light has turned on. When the system is operating correctly air will flow
into the top of the filter and the flags should start turning white as the water level drops.
(a) If the air blanket solenoid valve light does not come on, notify direct support maintenance.
(b) If the light comes on but the flags do not turn white, go to step 3.
Air flows into the filter at a low rate. Do not assume the air blanket is not working if the
flags dont turn over at a high rate of speed.
Check the media filter inlet pressure and the air system pressure. The air pressure must be 10-15 psig
higher than the media filter pressure to allow air to flow into the filter.
(a) Adjust the air pressure up if the two pressures are close to each other.
(b) If the flags still do not turn white, go to step 4.
Disconnect the air blanket solenoid valve connector, J47. Check for 110-120 VAC across J47A and
P47B (Reference Interconnection Diagram FO-2, Sheet 15).
If voltage is not present, notify direct support maintenance.
Shut down the ROWPU. Open the vent valve on the media filter and relieve the media filter pressure.
Turn off the air compressor and close the air tank block valve. Open an air manifold drain valve and
vent off the air pressure in the system. Remove the airline to the air blanket solenoid valve at the sole-
noid valve. Open the air tank block valve and check for air flow through the disconnected line.
If air flows through the line, go to step 7.
Check the air blanket solenoid air line and block valve for plugging.
Replace/repair the air line or block valve (paras. 4-24 and 4-68).
Disassemble the air blanket solenoid and check valve. Inspect for plugging (para. 4-51).
Clean out any foreign matter in the valves.
Check for resistance. across pins P47A and P47B (Reference Interconnection Diagram FO-2, Sheet
15) of the air solenoid valve connector.
(a) If the multimeter reads infinity or short circuit, replace the air blanket solenoid valve (para.
(b) Return the ROWPU to operation after the above checks and repairs. Check the air blanket for
(c) Notify direct support maintenance.
2. Backwash air solenoid valve works but pilot light does not come on (Reference Schematic Diagram FO-1,
Sheet 7, schematic lines 727-728).
Notify direct support maintenance.
3. Media filter backwash cycle works okay until water starts filling the filter during phase 2 and then the backwash
stops (Reference Schematic Diagram FO-1, Sheet 7, schematic line 705).
Notify direct support maintenance.
4. Filter media comes out the waste line when backwashing (Reference Schematic Diagram FO-1, Sheet 8, sche-
matic lines 802-804).
Five things can cause this problem. Check that the first three are not causing the
problem before checking the last two.