ASSEMBLY AND PREPARATION FOR USE - cont

Section III. OPERATION UNDER USUAL CONDITIONS - TM-10-4320-345-13_40

ASSEMBLY AND PREPARATION FOR USE - cont - TM-10-4320-345-13_42

TM-10-4320-345-13 Tactical Water Distribution System Model TWDS20 NSN: 4320-01-361-9232 Manual
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TM 10-4320-345-13 2-11. ASSEMBLY AND PREPARATION FOR USE - cont. (e) Keep security precautions in mind. Utilize natural camouflage wherever possible and avoid routing hoseline through populated areas. (5) In selecting pumping station installation sites, the location of the lead or first pumping station will be determined by location of the water source. Boost pumping stations are intended to be spaced at approximately two mile intervals, assuming that the route is reasonably direct and terrain is level. However, a substantial rise or fall in elevation along the hoseline route may require adjustment of standard spacing intervals. (a) If the next downline pumping stations is substantially higher in elevation than the upline pumping station, the distance between them must be shortened. (b) If the next downline pumping station is substantially lower in elevation than the upline pumping station, the distance between them must be lengthened. (6) Adjustments to spacing between pumping stations (due to elevation change) assure that water pressure will be maintained within optimum operational range. Under normal conditions, TWDS will deliver water to the suction port of each boost pumping station at a pressure of 20 psig. Whenever suction pressure falls below 20 psig, boost pumping stations are designed to begin reducing speed, when operated in the electric mode. Therefore, if an upline pumping station is substantially lower than the next downline station, and the elevation difference has not been offset by spacing adjustment, suction pressure at the downline pumping station may fall below 20 psig and cause that pump to slow down. This in turn will cause remaining downline boost pumping stations to slow down, seriously degrading overall performance of TWDS. (7) A ground profile (drawn on graph paper) and a pump spacing triangle can be utilized to determine the location of each boost pumping station. To construct a ground profile, first obtain a topographical map or other source material which provides accurate information concerning terrain along projected hoseline route. Then, using this information, draw a ground profile of the hoseline route on graph paper as follows (refer to figure 2-8). (a) Divide the horizontal base of the graph into spaces that represent uniform distances, such as 1000 ft intervals. However, any suitable scale can be used. The base of the graph represents the horizontal distance that the hoseline will cross. (b) Divide the vertical, left-hand edge of the graph into spaces that represent uniform changes in elevation. (c) At the left-hand edge of the graph, mark a point that represents the elevation of the lead pumping station. (d) Continuing across the graph, mark points where significant changes in elevation occur along the hoseline route. (e) To complete the ground profile, join the points marked on the graph with a straight line. 2-24

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