c. The following table gives minimums for aggregate valve port area and aggregate valve outlet area, for the different size plungers, figured on a basis of 56% of plunger area for a 12-inch stroke, and 64% for a 16-inch stroke.
| Size of Pump. | 500 gal. | 750 gal. | 1000 gal. | 1500 gal. | |
|---|---|---|---|---|---|
| 1 | Diameter of plunger. Inches | 71⁄4″ | 9″ | 10″ | 12″ |
| 2 | Area of plunger in sq. inches | 41·28 | 63·62 | 8·54 | 113·10 |
| 3 | 56% of plunger area,or Minimum aggregate valve port area allowed per section. Square inches | 23·11 | 35·63 | 43·98 | 64% = 72·38 |
| 4 | Minimum aggregate valve port circumference, allowed per section. Inches | 46·22 | 71·26 | 87·96 | 144·76 |
| 5 | Minimum aggregate valve outlet area allowed per section for valves lifted 1⁄2 inch high. Square inches | 23·11 | 35·63 | 43·98 | 72·38 |
d. If we consider using any one of the three sizes of valves below, whose port areas may be assumed approximately as
| Diam. Valve. | Diam. of Valve Port. Circ. | Circ. of V. C. Circle. | Valve Port Area (Net). Square inches. |
|---|---|---|---|
| 3″ | 21⁄2″ | 7·85″ | 3·5 |
| 31⁄2″ | 3″ | 9·42″ | 4·7 |
| 4″ | 31⁄2″ | 10·99″ | 6·3 |
given, then the necessary number of valves per section will be as in the table following:
| Size of Pump. | 500 gal. | 750 gal. | 1000 gal. | 1500 gal. | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Size of Valves. | 3″ | 31⁄2″ | 4″ | 3″ | 31⁄2″ | 4″ | 3″ | 31⁄2″ | 4″ | 3″ | 31⁄2″ | 4″ |
Necessary number of valves to satisfy (4) under c | 6 | 5 | 5 | 9 | 8 | 7 | 11 | 10 | 8 | 19 | 16 | 14 |
Necessary number of valves to satisfy (3) under c | 7 | 5 | 4 | 10 | 8 | 6 | 13 | 10 | 7 | 21 | 16 | 12 |
The exact number and size of valves will, however, not be insisted upon provided the aggregate valve area and the aggregate valve outlet area for each section is not less than that given in the table under c for the limiting lift of 1⁄2 inch.
Manufacturers will note that with the established lift of 1⁄2 inch, the 31⁄2-inch valve will permit a valve outlet area more nearly equal to its port area than will either the 3-inch or 4-inch valves, and a relatively less number of valves will satisfy the specifications.