Fig. 596.
Note.—Tank Valves. The “Corcoran” valve is made for either side or bottom outlet and for 1, 11⁄4, 11⁄2, 2 and 21⁄2 inch pipe; its action is automatic; the pull by which it is operated is controlled by a ratchet. This valve closes the pipe inside the tank. It thus becomes easy to empty the pipes in order to prevent freezing. The hoops, lugs and lock nut nipples are important parts of a well constructed tank. The foundations upon which tanks are supported should be carefully considered, as the average weight of a well made tank, when full of water, is about five tons to 1000 gallons.
The following table gives the capacity of round tanks or cisterns for each 12 inches in depth, if the tank is 24 inches deep instead of 12 inches, the result would be, twice the number of gallons.
Table.
| DIAM. | GALL. |
|---|---|
| 25 feet | 3671 |
| 20 „ | 2349 |
| 15 „ | 1321 |
| 14 „ | 1150 |
| 13 „ | 992 |
| 12 „ | 846 |
| 11 „ | 710 |
| 10 „ | 587 |
| 9 „ | 475 |
| 8 „ | 376 |
| 7 „ | 287 |
| 61⁄2 „ | 247 |
| 6 „ | 211 |
| 5 „ | 147 |
| 4 „ | 94 |
| 3 „ | 53 |
| 21⁄2 „ | 36 |
| 2 „ | 23 |
The contents of cisterns and tanks are estimated either in gallons or in cubic feet. The weight of water in any cistern or tank can be ascertained by multiplying the number of gallons by the weight of one gallon, which is 81⁄3 pounds, 8.333. For instance, taking the largest cistern in the above table containing 3671 gallons: 3671 × 8.33 = 30579.43 lbs. (nearly).
If the cistern is rectangular, the number of gallons and weight of water are found by multiplying the dimensions of the cistern to get the cubical contents. For instance, for a cistern or tank 96 inches long, 72 inches wide, and 48 inches deep, the formula would be: 96 × 72 × 48 = 331,776 cubic inches.
As a gallon contains 231 cubic inches; 331,776 divided by 231 gives 1,436 gallons, which multiplied by 8.33 will give the weight of water in the cistern. Fig. [594].