TM 10-4610-241-10
TO 40W4-13-41
2-15. OPERATION OF AUXILIARY EQUIPMENT - cont
(4)
Calibration Check:
(a)
Set mode switch to "S" (an internal standard).
(b)
Press indicator button. Read the 0 to 5 scale to the nearest tenth.
(c)
For fresh water, meter is ready for use if it matches the 442 ppm internal standard marked on bottom
plate. For seawater or brackish water, meter is ready if its reading matches the "NaCI" internal
standard, which, if not stamped on bottom plate, was noted in step (3)(i).
(d)
If reading is not the same, notify unit maintenance to replace TDS meter.
CAUTION
To avoid shorting TDS meter, keep the meter dry. Do not spill water or any other liquid on the
meter. Do not damage meter by removing or twisting cell cup.
(5)
Test in.
NOTE
Be sure cell cup is clean; if required, wash with soap and the purest water available.
(a)
Rinse cell cup three times with water to be tested.
(b)
Fill cell cup to 1/2-inch from top with water to be tested.
CAUTION
To prevent damage to TDS meter, use range extender when testing source water of unknown
salinity.
NOTE
Do not use range extender when testing product water or fresh water.
(c)
Push range extender into cup, seating the preformed packing.
CAUTION
Always start with meter set in 1000 mode. If a lower scale is used first, the meter may be damaged.
(d)
Set mode switch to 1000 mode.
(e)
Press indicator button. If reading is more than 5,000, record reading. If reading is less than 5,000,
remove range extender.
(f)
Press indicator button. If reading is more than 500, record reading. If reading is less than 500, place
mode switch to 100.
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