Table 4-2. Unit Troubleshooting Guide (Continued)
TEST OR INSPECTION
12. High pressure pump starts but shuts down on product high pressure. System clean or heat-up operation.
Start the ROWPU and note the product pressure reading when the pump shuts down.
(a) If the pressure is below 40 psig (172 kPa), notify direct support maintenance to check operation of
the product high pressure switch.
(b) If the pressure is over 40 psig (207 kPa) the ROWPU is making too much water during these
operations. The product outlet hose to the distribution tanks will have to be brought inside and the
end placed into the top of the clean/flush tank. Open the product shut-off valve and continue
13. High pressure pump starts but shuts down on a feed high pressure alarm.
Notify direct support to check operation of the feed high pressure switch.
14. High pressure pump starts but shuts down on a feed low pressure alarm.
Start the ROWPU and watch the filter pressure gages. The two gages indicate water pressure in the system as it
flows through the filters.
The black needle indicates inlet pressure and the red needle indicates outlet pres-
sure. The red needle on the cartridge filter gage also indicates the pressure the
system is shutting down at.
There will always be a difference between the two needles, on each gage, when the
unit is operating at 100 gpm flow rate depending on how dirty the filter is. The media
filter differential pressure should read about 10 psi (69 kPa) when clean and will rise
to 25 psi (172 kPa) as it gets dirty. The cartridge filter differential pressure starts at
about 2 psi (14 kPa) clean and rises to 15 psi (103 kPa) as it gets dirty.
If the red needle on the cartridge filter reads over 10 psi (69 kPa) when the unit shuts down, notify
direct support maintenance to check operation of the feed low pressure switch.
If the differential pressure on the media filter shows it is dirty, backwash or troubleshoot the filter.
If the differential pressure on the cartridge filter shows it is dirty, change filters.
If both above checks are okay, check the basket strainer for plugging and service it if it is found to
be plugged and the alarm has not sounded. Refer to para. 2-24b(3).
If all the above checks are okay, troubleshoot the raw water pump and then the booster pump for
Does not supply sufficient flow (malfunction 6 and malfunction 8, respectively).
If troubleshooting does not reveal the problem, it may be necessary to operate without separators
at this site or replace/repair the raw water pump as the tests may not indicate a wear problem
which is only evident at full flow conditions.
Noise level high, piping may be shaking, high pressure pump may be making hammer sounds.
Step 1. Remove the tubing from the backwash air check valve at the media filter. Operate the ROWPU and check
if water flows out of the check valve.
If water comes out of the check valve, disassemble check valve and clean it out (para. 4-53).
If cleaning the check valve fails to stop water leakage, replace the backwash air check valve (para.
Check valve must be installed with the arrow pointing to the media filter.