Capacity M G D

FIGURE 8 System-head curves for variable-speed operation for the Forney raw water pumping station in Dallas (1 ft = 0.3048 m ; 1bhp = 0.746 bkW; 1 mgd = 157.7 m3/h) (URS/Forrest and Cotton)

and efficiency at varying speeds. Typical procedure for an installation with two variablespeed units is as follows:

1. If station flow is less than the capacity of one pump, one variable-speed unit is operated.

2. If station flow is between one and two times the capacity of a single unit, both variable-speed units are operated (in lieu of operating one unit at full speed and the other at a speed less than that required to produce minimum allowable flow).

3. If station flow is more than two times the capacity of a single unit, the two variablespeed units are operated, along with as many constant-speed units as are required to ensure operation of all pumps at speeds that will produce flows exceeding minimum requirements.

Survival Treasure

Survival Treasure

This is a collection of 3 guides all about survival. Within this collection you find the following titles: Outdoor Survival Skills, Survival Basics and The Wilderness Survival Guide.

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