If raw water hoses freeze, poor water flow will reduce pressure in R.O. pump.
The R.O. PUMP LOW PRESSURE lamp will come on and R.O. pump will shut
itself off. Bring hoses under cover until ice melts.
The ROWPU produces less product water when the temperature of raw water
When the ROWPU is shut down during cold weather (temperature falls below 32 °F (0 °C),
remove the R.O. elements (para. 3-4) . Store the elements indoors or in a tent where the temperature is above
freezing and allow them to dry. Drain all water from ROWPU as follows:
Make sure drained water runs toward lower ground (downstream) as far from
the raw water source as possible.
(1) Drain ROWPU pipe, filters, and connections:
(a) Open seven drain valves (para. 2-38).
(b) Open five vent valves (para. 2-23 b).
(c) Facing trailer from towing end, jack-up left side to permit maximum water drainage
through drain valves.
(2) Drain R.O. pump as described below:
Do not operate R.O. PUMP JOG switch (42, fig. 2-4) for more than 5 seconds at
a time. You will damage pump if you do.
The JOG switch can be used when the R.O. pump LOW PRESSURE lamp is
(a) After water stops flowing out of drains, set R.O. PUMP JOG switch to JOG. Hold it there
for 3 to 5 seconds to force water from pump.
(b) Repeat operation of R.O. PUMP with JOG switch until no more water comes from the
DRAIN PULSE DAMPENER drain (fig. 2-39).
(c) Disconnect plastic tubing from bottom of R.O. vessels so they can drain. Reconnect
tubing when vessels are fully drained.