TM 5-4610-223-12
washed away. When valve CV-36 is in WASH position it allows the water to enter the wash ring (6, fig. 2-28) and wash
the sediment from the bottom of the filter. After washing, filters are ready for precoating.
c.
Operating Details. After the water purification unit Is in operation, there are certain adjustments to be made and
procedures to be followed. This will depend on the quality and quantity of the raw water being pumped.
(1)
Adjustment of chemical dosage settings.
(a)
General. The operator must apply proper chemical treatment based on clarity of the water above
slurry pool in erdlator tank, filterability of this water, and the length of filter run. Raider Model only loosen thumbscrew (2,
fig. 2-5.1) and rotate ferric chloride control knob (1) to a higher stroke setting. Retighten thumbscrew.
(b)
Treated water looks cloudy. If the treated water above the slurry blanket in the erdlator tank looks
cloudy, Increase the ferric chloride solution rate of discharge. Move the feed indicator FEI-7 (5, fig. 2-5) to a higher
feeder scale (9) reading. Use the ferric chloride solution calibration chart (fig. 2-9) as an aid in determining the proper
setting. A more accurate determination of the proper chemical feed rates for the operation of the water purification unit
can be determined by the use of the Water Quality Analysis Set (WQAS). Refer to TM 5-6630-215-12, Water Quality
Analysis Set, Preventive Medicine (NSN 6630-00-140-7826), Engineer (NSN 6630-00140-7820).
(c)
Treated water has reddish color. If the treated water above ,slurry blanket in the erdlator tank begins to have
a reddish color, decrease the ferric chloride solution rate of discharge. Move the feed indicator FEI-7 (5, fig. 2-5) to a
lower feeder scale (9) reading. Raider Model only loosen thumbscrew (2, fig. 2-5.1) and rotate ferric chloride control
knob (1) to a higher stroke setting. Retighten thumbscrew. Use the terric chloride solution calibration chart (fig.
2-9) as an aid in determining the proper setting. Use Water Quality Analysis Set (WQAS) for more accurate
determination of proper chemical feed rates.
(d)
Treated water is clear with large particles and blanket fluffy. If the treated water above the slurry blanket in
the erdlator tank looks clear but large particles are rising and the blanket looks light and fluffy, increase the limestone
slurry rate of discharge. Move the variator feed indicator FEI-6 (1, fig. 2-14) to a higher feeder scale reading. Use the
limestone slurry calibration chart (fig. 2-12) as an aid in determining the proper setting. Use Water Quality Analysis Set
to determine the best chemical feed rate.
(e)
Visible limestone in sample from sludge concentrator tank. If a sample of slurry, withdrawn from the bottom
of the sludge concentrator tank, contains visible quantities of limestone, decrease the limestone slurry rate of discharge.
Move the variator feed indicator FEI-6 (1, fig. 2-14), to a lower feeder scale reading.
Use the limestone slurry calibration chart (fig. 2-13) as an aid in determining the proper setting.
(f)
Chlorine residue. In order to maintain a chlorine residual in the filtered water, determine the chlorine residual
(para
Change 4 2-53
