(c) Determine flow in cubic feet per second by multiplying velocity by
cross-sectional area. Example:
A = 24.5 ft2
V = 0.5 ft/sec
Q = .85 X 24 5 ft2 X 0.5 ft/sec = 10.4 ft3/sec.
The flow in ft3/sec may then be converted to gallons per minute by multiplying by 448.8:
10.4 ft3/sec x 448.8 gal/ft3 = 4,668 gpm (4,667.52).
OPERATION OF FIELD WATER PURIFICATION EQUIPMENT
Field water purification equipment was briefly discussed in Lesson 1. The
following paragraphs describe in considerably more detaiI the flow of water through the
erdlator and the specific operations that take place. It is once again emphasized that
the preventive medicine specialist need not be a trained erdlator operator; however, the
more knowledge he has of the operation of the equipment, the better able he wiII be
able to inspect a water point and make recommendations for improvement.
INSTALLATION OF WATER PURIFICATION EQUIPMENT
Figure 5-5 illustrates a typical field water purification unit (WPU) installation. The
following points are important in the proper selection and setting up of the unit:
a. Site Selection. Although it is not always possible under tactical conditions to
select an ideal site for the WPU, the site selected should meet as many of the following
requirements as possible:
(1) The site should provide natural camouflage; access to roads, water
supply sources, and power Iines, and surrounding bivouac areas for operating
The site should require minimum improvements.
The terrain should be as level as possible.
(4) The area should be large enough to accommodate all component parts
of the WPU and to provide turn-around space for the water transporting vehicles.
b. Locating Equipment.
(1) The truck mounted WPU (see figure 5-5, circle A) should be located as
close to the water as possible, preferably not more than 50 feet away. Avoid taking
water near a bathing area, sewer outlet, or latrine. A firm, level footing should be
selected and improved, as necessary, by digging ditches and/or installing blocks or
timbers under the wheels and leveling jacks. The van body housing the WPU should be