To read rate of flow in GPM, drop down to the X axis and read the answer 850 GPM.

To determine the efficiency, drop down to the efficiency curve and read the percent efficiency in the

right-hand margin (70%).

The BHP is similarly read. Drop down to the BHP curve for gasoline and read the answer (35 BHP).

gravity diesel fuel.

Individual pump stations must regulate pump speed to keep suction pressures at the next pump station

downstream above the minimum. The normal suction pressure at a pump station is 20 PSI for elevations

less than 5,000 feet and where temperatures are below 100 degrees Fahrenheit (20 PSI is equivalent to 64

feet of head of MOGAS). The minimum suction pressure at a pump station must be 5 PSI because of pump

entrance friction losses and the possibility of vapor lock in the pump. Five (5) PSI is equivalent to 16 feet of

head of MOGAS. To determine flow rate, efficiency, and BHP in pump station operations, the total pressure

produced on the discharge side of the pump station must be determined first.

pressure of 480 PSI and a suction pressure of 20 PSI. They are pumping a product which has

a SP/GR 0.8254.

480 PSI minus 20 PSI = 460 PSI.

2.31*x*460

1,287

0.8254

In order to use the pump graph, divide 1,287 ft/hd by three because there are three pumps on line (429

ft/hd). Locate 429 feet of head on the graph, read to the right of the head curve (1,800 RPM). Read down to

600 GPM. At that flow rate, read up the graph until the line intersects the brake horsepower curve at 1,800

and read 68 BHP. This represents one pump and there are three on line. Multiplying by three gives you 204

BHP for the station. In the same manner, read up to the efficiency curve and read 74 percent. As shown,

the graphs can be used for pump stations as well as individual pumps.

and interpreted the same as the other pump graphs used. It shows total dynamic heads in PSI, feet of head,

and flow rate for water (1.0 sp/gr), DF-2 (0.8254 sp/gr), and MOGAS (0.7254 spgr) from 770 RPM to 2,100

RPM.

For example, at a flow rate of 500 GPM and 1,800 RPM pumping DF-2, the pressure and feet of head

can be determined. Locate 500 GPM and read up to the 1,800 RPM curve. Reading to the left gives 1,359

ft/hd at 500 PSI.

5-4

QM 5096