(2) Built-in features include:
(a) The ROWPU container is insulated and weather sealed.
(b) The container floor drain sumps include electric heat tracing pads to prevent freezing when the main control
panel sump heat switch is on.
(c) Space heaters. Two diesel fueled space heaters are provided in the ROWPU van for heating during transport
and mission operation.
(d) The high pressure pump assembly has a built in electric heater.
The van heaters draw fuel from the diesel generator fuel tank at 1/6 gallon per hour each. The electrical power is 24
VDC supplied as follows:
From the diesel generator batteries.
From a power supply when the generator is operating and the main control panel heater switch is on.
From a power supply when auxiliary 120 VAC power is connected and the main control panel heater switch
If not powered through the power supply, power is drawn automatically from the diesel generator batteries. At -25°F
(-32°C) one heater may safely be powered for one hour without risk of excessive battery discharge.
(e) Auxiliary power connection. A connection for an external 120 VAC power supply is provided. With the heater
power supply switch on, this will power the space heaters through the power supply. Cable must be two wire plug with
(f) Air purge. The media filter and NBC filter both include a connection to use ROWPU service air to rapidly purge
the water from these filters to avoid severe freeze up.
(3) Winter kit (Figure 1-6) includes:
(a) Two electric heat lamps (2 and 3) are provided, one for the distribution pump and one for the raw water pump.
These lamps are to be connected to heater outlets at each side of the ROWPU and provide heat to the inside of the pump
covers when the pumps are not operating.
(b) A non-floating intake strainer (1) is provided for use when taking water from an ice hole.
(c) A cable (5) to connect one of the diesel heaters to the generator battery during transport or when the power to
the ROWPU is off.
(d) An extension cable (4), if required, for the raw water pump heat lamp.
(e) Covers to cover the raw water pump and distribution pump.
(f) Skids to keep the raw water pump and distribution pump off the ground.
c. Freeze Protection, General Guidelines and Instructions.
(1) RO vessels and elements. Freeze up during deployment must be avoided to assure continued ROWPU
(a) Use the space heaters to maintain ROWPU van temperature over 35°F (2°C). Do not exceed time limitations
(b) Draining will avoid freeze up of feed and waste piping which may generate damaging ice pieces upon
(c) Draining does not remove all water from the vessels and RO elements. The RO elements are like a wet cloth
and hold some water after draining. If ice is present in the RO element or vessel when the ROWPU is started, the
elements may be damaged. Damage is noted by a high product water TDS because of water passing directly through
holes in the membrane material.
(d) If the ROWPU is drained and allowed to freeze, thawing will require 2 days with additional heat provided to
bring the temperature up to at least 85°F (30°C) or 8 days at 45°F (7°C).
(e) If freezing cannot be avoided, the elements should be removed, stood on end for 30 minutes to assure
drainage, and properly sealed in an air tight plastic bag.
(f) Stand-by power should be available to prevent freezing in the event of generator failure.
(2) Chemicals. Both polyelectrolyte and sequestrant will freeze, but will not lose performance when thawed.
Completely thaw before using. If cloudy, mix before using.