ARMY TM 10-4610-309-14
MARINE CORPS TM 10802A-14/1
TACTICAL WATER PURIFICATION SYSTEM (TWPS)
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OPERATOR INSTRUCTIONS
MAINTAINING NORMAL OPERATION UNDER USUAL CONDITIONS
e. RO % Clean also decreases if salt scale, dirt or biological growth build up on the
membrane surface.
f. A decrease of 10% or more in RO % Clean during operation indicates that the RO needs
to be cleaned.
g. Water production listed in Table 2 can be obtained with RO % Clean values which equal
or exceed the values listed below.
Fresh water and brackish water to 5000 mg/l
50%
Normal seawater (35,000 mg/l)
70%
45,000 mg/l sea water
79%
60,000 mg/l sea water
79%
h. With lower RO% Clean values, the maximum operating pressure will be reached before
reaching the listed water production.
2. % Salt Rejection
a. The % Salt Rejection value is displayed on the OCP. It shows the percentage of salt that
is rejected from the feed water as the water passes through the membrane to become
product water. This value is calculated by the PLC using the feed water TDS entered by
the operator, the product measured TDS, the feed water temperature and the product
flow rate.
b. The % salt rejection decreases with increasing temperature.
c. The % Salt Rejection decreases as the RO membrane ages and if salt scale builds on
the membrane surface during operation.
d. Compare the % Salt Rejection readings with the values listed in Table 3. If a reading is
close to the minimum and dropping, schedule the checks and corrective action listed in
Table 5 under "Product TDS High" Alarm. When % Salt rejection falls below the
minimum, the alarm will come on. The alarm also comes on if the measured TDS is
greater than 1000 mg/l.
Table 3. Expected Salt Rejection Readings.
Raw Water
Expected
Minimum
Seawater and other sources over 20,000 mg/l
99.2% or higher
98.5%
Brackish water 5000 to 20,000 mg/l
99.2% or higher
98%
Fresh water and brackish water to 5000 mg/l
99.2% or higher
95%
3. RO Cleaning Indication:
a. The need to schedule cleaning of the RO, and the type of cleaning required, is indicated
by changes in the RO% Clean and % Salt Rejection values. Refer to Table 4.
b. If the % Salt rejection is close to the minimum value, refer to Table 5, under the heading
"Product TDS High".
DETERMINING RO CLEANING REQUIREMENTS
NOTE
If you are not certain which RO cleaning procedure is needed, complete both the low pH
acid and high pH detergent cleaning.
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