MARINE PUMPS.
These are made both horizontal and vertical; the prime consideration being in all cases the amount of floor space the pump will require. This is especially true in reference to small steam vessels, pleasure craft, etc.
Owing to the unusual corrosion, caused by galvanic action, salt and various impurities, marine pumps are built of iron with brass linings, but frequently with the entire water ends of bronze.
The arrangement of the water valves in the most approved forms of vertical pumps is such that the pistons are always submerged, and the water valves sealed, thereby securing immediate lift of water through the suction pipe, and steady, quiet operation of the pump; many horizontal pumps of the ordinary duplex design are also used on shipboard.
The ship’s pump is common to all vessels and used to keep the “hold” free from water. It is usually worked by hand but it is the law in certain countries that the “ship’s pump,” aside from steam vessels—shall be driven by windmill power; it is said to be an odd sight to see the practical working of these at sea.
Fig. 447.
The illustration on page 156 shows a marine vertical pump of the Davidson pattern, designed to work against a pressure of 250 pounds per square inch. The table given herewith will show the sizes and principal details of these pumps.
Table.
| Steam Cylinder | Water Cylinder | Stroke, Inches. | Gallons per Single Stroke of Each Piston. | Horse-power of Boiler, based on 30 lbs. of water per H. P. per hour, which the pump will supply with ease. | Steam Pipe | Exhaust Pipe | Suction Pipe | Discharge Pipe |
|---|---|---|---|---|---|---|---|---|
| 4 | 21⁄2 | 4 | .084 | 165 H. P. | 1⁄2 | 3⁄4 | 2 | 11⁄2 |
| 41⁄2 | 23⁄4 | 6 | .154 | 300 „ | 1⁄2 | 3⁄4 | 21⁄2 | 2 |
| 51⁄2 | 31⁄2 | 6 | .15 | 500 „ | 1 | 11⁄4 | 3 | 21⁄2 |
| 6 | 4 | 8 | .435 | 870 „ | 1 | 11⁄4 | 31⁄2 | 3 |
| 7 | 4 | 8 | .435 | 870 „ | 11⁄4 | 11⁄2 | 31⁄2 | 3 |
| 7 | 41⁄2 | 8 | .55 | 1,100 „ | 11⁄4 | 11⁄2 | 4 | 3 |
| 8 | 5 | 10 | .85 | 1,700 „ | 11⁄2 | 2 | 41⁄2 | 31⁄2 |
| 8 | 5 | 12 | 1.02 | 2,000 „ | 11⁄2 | 2 | 41⁄2 | 31⁄2 |
| 9 | 51⁄2 | 10 | 1.03 | 2,000 „ | 11⁄2 | 2 | 41⁄2 | 4 |
| 10 | 6 | 10 | 1.225 | 2,450 „ | 2 | 21⁄2 | 5 | 41⁄2 |
| 10 | 6 | 12 | 1.469 | 2,900 „ | 2 | 21⁄2 | 5 | 41⁄2 |
| 12 | 7 | 12 | 2.00 | 4,000 „ | 2 | 21⁄2 | 6 | 5 |
The capacity for boiler feeding in the table is based upon sixty single strokes for each pump per minute.
The suction and discharge openings, as will be seen in the figure, are on both sides. The water piston is packed for hot and cold water and special valves are furnished as may be necessary.