| 33,000 × 200 | ||
| A = | —————— | = 192.4 square inches. |
| 49 × 700 |
The nearest piston diameter of even inches is 16, which corresponds to an area of 201 square inches. Assume a piston rod diameter of 21⁄2 inches, corresponding to an area of 4.9 square inches, from which the average or effective piston area is found to be (2 × 201) - 4.9⁄2 = 198.5 square inches.
Determining now the new piston speed, we have:
| 700 × 192.4 | |
| ————— | = 678.5 feet per minute. |
| 198.5 |
Assuming the length of stroke to be 1.5 times the diameter of the cylinder, it will be 24 inches, or 2 feet.
This will call for 678.5 ÷ 2 = 340 strokes per minute, approximately, or 340 ÷ 2 = 170 revolutions per minute.