T M 1 0 - 4 6 1 0 - 2 3 2 - 12
Table 4-2. Unit Troubleshooting Guide (Continued)
TEST OR INSPECTION
The media was just changed or media was added and has not been wet-for 24 hours. See
Too much media in the filter. Refer to para. 4-53 for the correct leveI. The situation is self
Too high a flow rate during backwashing. Check operating conditions and ensure the correct
flow rates for each phase and for the operating temperature.
Leaking backwash air solenoid valve.
Media filter level assembly not working correctly. The bottom switch is possibly stuck dosed
which can allow the fitter to start backwashing with too high a water level.
Check that the backwash air solenoid is not leaking by shutting down the ROWPU and opening the
media filter vent valve to relieve filter pressure, Remove the tubing on the outlet of the solenoid valve.
Place a finger tightly over the valve outlet fitting. If it is leaking, air pressure will build up and force its
way past the finger.
(a) if the valve is leaking air, disassemble it and clean it out (para. 4-51).
(b) if cleaning if out does not stop the air leakage, replace the valve assembly (para. 4-51).
Disconnect connector P35 (Reference interconnection Diagram FO-2, Sheet 1) at the bottom
switch of the media level assembly. Remove the bottom of the Ievel assembly and remove the flat.
Be careful when removing the float. It will drop out when the cover is removed from the level assembly.
Check for continuity across J35A and J35B with the float removed.
If there is no continuity, replace the bottom level switch, LSLL (Reference Interconnection Diagram
FO-2, Sheet 15) para. 4-52).
Check that J35A and J35B show continuity and insert the float into the level chamber with the arrow
up. Slowly push it up the chamber and watch the muitimeter. it should show the switch opening as the
float goes past it and stay open. Slowly let the float drop and watch that the switch closes as the float
goes y it. it should then stay closed. heck that the flags turn red as the float is pushed up the cham-
ber and turn white as it comes down.
(a) If the flags dont turn, replace the float (par and test the flags and switch again.
(b) If the switch (LSLL) does not operate as replace it (para. 4-52).
(c) Return the ROWPU to operation and check operattion.
5. Air does not go into media filter during backwash. (Air system gage does not show any or very littie drop in
pressure) backwash air valve light is "on" indicating proper operaton.
Step 1. Shutdown the ROWPU. Open the media filter vent valve and relieve pressure on the filter. Remove
the tubing on the outlet of the backwash air solenoid valve. Close the media fitter vent valve, initiate
the backwash code, and check to see if air comes out of the solenoid valve during the second phase of
backwashing. Check that water does not flow out of the backwash air check valve on the media filter
during the backwash operation.
(a) If water flows out of the check valve, disassetile it and clean it out (para. 4-53). Reinstall it
and check if water flows out of it. Replace it if the Clean did not stop water flow (para. 4-53).
(b) if air flows freely out of the solenoid valve and the air system pressure gage drops from
400-500 pounds during the second phase of backwashing, go to step 2.
(c) if little or no air flows from the solenoid valve, disassemblet and dean it out (para. 4-51).
(d) Notify direct support maintenance to check backwash circuits phase 2 for eiectrical checks on
the backwash air soienoid.
Step 2. Remove the backwash air check valve. Disassemble and dean it out (para. 4-53). Operate the
ROWPU in system NORMAL with just the raw water pump on and the backwash air check valve off
of the filter. Flush water until anything plugging the media filter air manifold is washed out.
When the water coming out of the filter check tubing is free of debris, reinstaii the check valve.