TM 10-4610-232-12
Table 4-2. Unit Troubleshooting Guide (Continued)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
NOTE
When the media has been changed the filter must be backwashed at a reduced flow
rate until the media has been in water for 24 hours or it will flush out of the filter.
Inform the operators to backwash at a maximum flow rate of 50 gpm during the 24
hour period.
Step 3. Check the media that is removed from the filter.
(a) If the media is sticky or has a lot of mud on it, disassemble the backwash air solenoid and check
valve and clean them out (paras. 4-45 and 4-51).
(b) Observe the next backwash and watch the air regulator high pressure gage during the air cycle
portion of the backwash. It should drop in pressure by 300-400 psig (2067-2756 kPa). If it doesn’t,
troubleshoot the backwash air circuit for electrical operation and for plugging of the air tubing,
backwash solenoid valve, backwash check valve, and media filter backwash air manifold. (Refer to
media filter electrical troubleshooting, malfunction 5.)
3. Media filter pressure drop exceeds 15 psig (103 kPa) after reconditioning and backwash.
Step 1. Check that media filter pressure gage is accurate.
(a) Remove pressure from system and note that the gage reads zero and that both the black and red
needles read the same (are on top of each other).
(b) Inform direct support maintenance to replace the gage if it is inaccurate.
NOTE
Operation can continue until the gage is replaced, if the difference in readings of the
gage, with no pressure on it, are subtracted from the reading obtained when
operating and the result indicates a pressure drop of less than 15 psig (103 kPa).
(c) If the pressure drop is greater than 15 psig(103 kPa), replace the filter media (para. 4-53).
NOTE
When the media has been changed the filter must be backwashed at a reduced flow
rate until the media has been in water for 24 hours or it will flush out of the filter.
Inform the operators to backwash at a maximum flow rate of 50 gpm during this
period.
Step 2. Check the media that is removed from the filter.
(a) If the media is sticky or has a lot of mud in it, disassemble the backwash air solenoid and check
valves and clean them out (paras. 4-45 and 4-51).
(b) Observe the next backwash and watch the air regulator high pressure gage during the air cycle
portion of the backwash. It should drop in pressure by 300-400 psig. If it doesn’t, troubleshoot the
backwash air circuit for electrical operation and for plugging of the air tubing, backwash solenoid
valve, backwash check valve, and media filter backwash air manifold. (Refer to electrical
troubleshooting.)
4. Media filter drain sump has media in it.
Check to see if the filter has too much media (para. 3-23) in it or if the filter has been drained down manually and
the upper media drain valve was left open after the raw water pump was started for backwash.
(a) If the problem is due to too much media in the filter, it will stop when enough media is lost and the
media level is correct.
(b) If the problem is due to manual draindown for backwash, troubleshoot media filter air blanket
(malfunction 1).
(c) If the problem is not in the air blanket system, notify direct support maintenance to troubleshoot
media filter backwash circuits.
4-20
