ARMY TM 10-4610-309-14
MARINE CORPS TM 10802A-14/1
TACTICAL WATER PURIFICATION SYSTEM (TWPS)
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DESCRIPTION AND THEORY OF OPERATION
THEORY OF OPERATION
Filtrate from the MF system is stored in the RO Feed Tank T-2 (see Figure 9). The RO feed tank stores a
sufficient supply of filtrate to allow the production of product water to continue uninterrupted during the
intervals when the MF modules are being backwashed. This tank is also used for cleaning solutions
when cleaning the RO and MF.
Level Transmitter LT-201 provides the level measurement for PLC control of the tank level. After a
backwash, the filtrate flows at approximately 62 gpm to refill the tank until the level reaches the high-level
point. After reaching the high level point, the level is controlled to remain at this point until the next
backwash. The tank level is displayed on the OCP as percent of high level.
Temperature Indicator TI-202 is a dial thermometer threaded into the RO feed tank.
Tank Heaters H-1 and H-2 are used for heating cleaning solutions and, if needed, to provide added
generator load to avoid wet stacking during normal operation.
Strainer S-3 sits inside the tank over the RO feed pump suction to prevent objects, which may fall into the
tank, from entering the pump.
RO Feed Pump P-4 draws filtrate from the tank as RO feed water and provides the pressure needed by
the HP Pumps. With cleaning bypass valves properly set, this pump also circulates the cleaning solutions
used when cleaning either the MF or RO.
Antiscalant Injection Check Valve V-623 is connected between the RO Feed Pump and V-212. The
injection check valve injects a measured amount of antiscalant into the RO feed water leaving the feed
pump. This antiscalant inhibits salt scale formation on the RO membranes. (See Chemical Injection
System for further explanation.)
High Pressure Pump (HPP) Feed Valve V-212 is open for normal operation and is manually closed for
cleaning and when removing the Inline Strainer S-4.
Strainer S-4 protects the HP pumps by removing sand and dirt, which may blow into the RO feed tank.
S-4 Drain Valve V-213 at the bottom of Strainer S-4 is used to drain the strainer.
RO Feed Pressure Gauge PI-202 indicates the pressure from the RO feed pump for operator reference.
Usual pressure is 40 to 45 psig.
RO Feed Pressure Transmitter PT-201 provides a pressure measurement that is used by the PLC to
protect the HP pumps. The transmitter and PLC set off an alarm and shut down the HP pumps when the
pressure from the RO feed pump drops below 35 psig.
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