Ship's pump

“ My plans are to apply all the engine-power of the ship to pumps for propulsion, and which can be used for pumping out leakage and propelling at the same time. In the largest pump I have made, 800 indicated horse-power discharged 350 tons of water a minute, and propelled the vessel faster than her sister ships with twin screws. The hydraulic propeller is of greatest value for the highest speeds, and has the greatest power of control. As the hydraulic is capable of subdivision to a great degree, the greatest amount of safety is possible. ”

“ Once again our engines were causing trouble: the circulating pump had gone “phutt,” and it was necessary for all hands to turn out and pump the bilges clear. A lovely job, there in the darkness, with the ship trying to tie knots in herself! And bilge water is so pleasant! Pumping is a back-aching job at best, but when you’re performing nautical gymnastics throughout your spell it exercises every muscle in your body, and you marvel at the number of muscles you possess, when they’re all aching at once! ”

“ If her bottom does not drop out some of these odd times, and leave us in the lurch, we may think ourselves lucky."
After uttering these consolatory remarks, accompanied with a significant shrug, he resumed his labors at the pump.
The wind blew with violence through the day, and the leak kept increasing. There is probably no exercise more fatiguing than "pumping ship," as practised with the clumsy, awkward contrivances called PUMPS, which were generally in use among the merchant vessels of those days. ”

“ Close the hatches of the flooded compartments and drive the water out by forcing air in. It would not make the slightest difference how big the holes might be in the bottom, as the water would be expelled and kept out on the same principle as in the old-fashioned diving bell.' This suggestion carries with it a much larger and more important one—namely, the use of air pumps instead of water pumps to save a leaking ship while afloat. As Mr. Richards well remarks, the work of trying to pump out a leaky ship is not only enormously wasted while it is going on, but it is never finished. ”

“ We soon found our account in baling; the spare pump had been put down the fore hatchway, and a pump shifted to the fish-room; but the motion of the ship had washed the coals so small that they reached every part of the ship, and the pumps were soon choked. However, the water by noon had considerably diminished by working the buckets; but there appeared no prospect of saving the ship if the gale continued. The labour was too great to hold out without water: yet the people worked without a murmur, and indeed with cheerfulness. ”

“ To make this pump work I of course opened, and left open, the pump-pipe, so that the air from the interior rushed in and filled the tank as fast as the pump discharged the water, and at each stroke of the pump, after the first few, the boat, as I had hoped, began to rise; the water, having been just so much ballast to carry it down, being discharged by the pump, was just so much thrown overboard in weight to allow it to rise. ”

“ Let it get in and everything that before made your craft seaworthy will be an aid to your ending. Your ballast will be a weight to sink you, and the empty space that gave you buoyancy so much room to quickly fill with water.
After this, look to your pump. Where is it? In most yachts directly amidships, drawing out of a well over the lowest part of the keel. Where should it be? In the place where it can be used when most wanted—the bilge. You must have a means of drawing from the center, so you can pump out when at anchor or sailing upright. [73] But all pumps should have a bilge intake. ”

“ In the latter case, the water is kept under pressure by a large piston or ram heavily weighted, the entire receptacle being, of course, of water-tight construction and adapted to withstand pressure. The pump that supplies the tank is ordinarily made to work automatically, ceasing operation as soon as the ram [78] rises to the top of the receptacle, and beginning again whenever, through use of water, the ram begins to descend. Such an apparatus is called an accumulator. Such water engines have come into vogue only in comparatively recent times, being suggested by the steam engine. ”

“ The exhaust valve now opens and the piston starts to return. The low pressure steam instead of passing direct to the atmosphere, as is the case of a high pressure engine, flows into a chamber “C,” and is brought in contact with a spray of cold water. The heat being absorbed by the water, the steam is condensed and reduced in volume, thus forming a vacuum. It is, however, necessary to remove the water formed by the condensed steam together with the water admitted to condense the steam, also a small amount of air and vapor. For this purpose, a pump is required, which is called the air pump. ”

“ The two feedwater pumps (fig. 20) are located beneath the cab deck (1, fig. 17) . They are cast-iron construction and are driven by an eccentric on the driving-wheel axle (fig. 27) . The airchamber or dome (1, fig. 27) imparts a more steady flow of the water to the boiler by equalizing the surges of water from the reciprocating pump plunger. A steam line (3, fig. 18) , which heats the pump and prevents freezing in cold weather, is regulated by a valve in the cab (figs. 18, 27) . ”

“ Its low cost, as it does not require an engine or other machinery to operate it. A steam pipe connecting it with the boiler that is to furnish steam supply is all that is necessary, and after the pump is once adjusted, it will always be in order with free power when the steam is turned on. 2. It is absolutely noiseless in its operation; the slight click of the steam ball-valve in the neck-piece, as it changes its position, is the only evidence that it is working. ”

“ Pumps.—When steam is up, and the burner in full operation, the water in the boiler is quickly evaporated, and the renewal of the supply is performed by pump. The pump is usually driven off the cross-head, a part of the engine which has a constant up-and-down motion. On most of the smaller cars the water supply is carried in a horseshoe-shaped tank at the back, which half encircles the boiler. In the Serpollet the water-tank takes the place of the motor bonnet of a petrol car. ”

“ The automatic action of the pump and its speed are controlled by a float in the receiver operating directly, without the use of intervening levers, cranks and stuffing boxes, to open or close a governor valve in the steam supply pipe to the pump, thus making the action of the pump conditional upon the rise and fall of the float in the receiver. ”

“ With the exception of the entrance opening, the external surface of the impeller is exposed to the delivery pressure, so that there is a resultant upward pressure on each impeller, equal to the area of its entrance multiplied by the difference between the entrance and discharge pressures of that stage. If all the impellers are alike, the total upward thrust is equal to the product of entrance area multiplied by the total head on the pump. The pumps are so proportioned that this upward thrust slightly exceeds the weight of the rotating portion, consisting of impellers and shaft. ”

“ The Ballast Pumps and What They Do.—The pumps which pump the water from the ballast tanks are driven by electric motors. They must be powerful pumps, for they not only have to pump the water out of the tanks quickly, but they have to force it out against the pressure of water in which the submarine is submerged; this pressure increases the deeper the boat sinks, and it is often 80 pounds or more to the square inch. The pumps are controlled from the conning tower, and also from the navigating compartment. ”

“ The inside of the upper part of the plunger is threaded to receive the lower part with a cup leather packing and contains a valve of metal having a conical seat. Fig. 156 shows a design of a pump in common use in the 14th century.
Note.—The action of a pump is as follows: The piston or plunger by moving to one end, or out of the pump cylinder, leaves the space it occupied, or passed through, to be filled by something. As there is little or no air therein a partial vacuum is formed unless the supply to the pump is of sufficient force to follow the piston or plunger of its own accord. ”

“ As single-acting pumps give an intermittent discharge three are generally used on cranks at 120°. But with all pumps the variation of velocity of discharge would cause great waste of work in the delivery pipes when they are long, and even danger from the hydraulic ramming action of the long column of water. An air vessel is interposed between the pump and the delivery pipes, of a volume from 5 to 100 times the space described by the plunger per stroke. ”

“ In cases, however, where steam or electric power is available the pumps are sometimes worked by their means—more particularly on harbour and dock works. In such instances the air is not delivered direct from the pump to the diver, but is delivered into an intermediate steel receiver to which the diver’s air pipe is connected, the object being to ensure a reserve supply of air in case of a breakdown of the pump. ”

“ European centrifugal pumps with their small impellers and consequent high speed of rotation, are especially liable to this repelling action, and very often are wholly inefficient from this cause. One maker who claims a high duty for his pumps, attaches a screw at the sides of the impeller to coax the water into the pump, and the idea is a good one if the difficulty is not otherwise provided for. In this way a pump can be made of smaller diameter for a given duty, but it is commonly inferior to a larger one for the same work.”—Industries. ”

“ A pump is said to “hesitate” when the motion becomes uncertain.
Horse-power of a pump. Is the same as is used to designate that of a steam engine, with this exception: the initial pressure in the pump remains constant throughout the stroke. Formula is the same as for a steam engine.
“Hump.” This is an arch or bend which causes an “air pocket” in a water-pipe line.
Hydrant. A valve and spout connecting with a street main.
Hydraulic Belt. An endless woolen band for raising water. The lower bight is immersed in water, and the upper bight passes over a roller. ”

“ The suction valves require more generous port-circumference and port-area than delivery valves because when a pump has to suck its supply through a considerable height or through a long pipe there should be the least practicable waste of the atmospheric pressure in getting the water into the plunger chamber, or in retarding it from following the plunger in full contact. With the water once into the plunger chamber there is plenty of steam pressure available to force it out through the delivery valves. ”

“ It is plunged almost entirely in water, oil, mercury (or other heavy fluid) contained in the vessel A B. It’s axis carries a waved wheel a b, on which rolls a friction-pulley p, running on a pin in the mortice of the bar c d. This bar works the pump f; which by the descent of it’s loaded Piston, drives cold air (or gas) into the tube g, communicating with several collateral ones placed across the vessel, so as to convey the air to h, below and beyond the centre of the wheel. A fire being made at F under this vessel, the water (or other fluid) is brought to a proper heat ”

“ The high-class turbine pumps of to-day are simply machines in which the water is given a velocity which is partially changed to pressure before discharge, and the pump is designed so that the well-known actions, outlined above, proceed along natural lines, which are, to use the common phrase, lines of least resistance. It is simply a question of careful design.
The modern pump causes the water to flow along paths naturally due to the forces acting and to guide the stream in such a way as to avoid the production of eddies and whirls within itself which so enormously cut down the efficiency. ”

“ Careful experiments on a large number of pumps of various makes at full speed, show that in a new pump with clean valves, and an air-tight suction pipe, and less than 15 feet lift, the actual delivery is only from 11⁄2 to 5 per cent. less than plunger displacement. This slip will increase with wear, and for a good average pump in practical use, probably 10 per cent. is a fair allowance to cover slip, valve leakage, slight short-stroke, etc. ”

“ The pump at the lower right-hand corner of the engraving takes salt water through the suction at the bottom and passes it upward through the condenser and overboard through the circulation discharge. Any steam pump having a sufficient capacity may be used as a circulating pump.
169
ATMOSPHERIC PUMPS.
The Bliss-Heath Atmospheric Pumping Engine represented by Fig. 455 is novel in its construction, consisting of a low-pressure, upright, tubular steam boiler, having a safety valve loaded to carry 11⁄2 lbs. steam pressure. The large cover lifts under 2 lbs. pressure, hence explosions cannot occur. ”

“ A.--The feed pumps are of brass, with plungers 4 inches diameter and 3-1/4 inches stroke. The feed pipe is of copper, 2 inches diameter. A good deal of trouble has been experienced in locomotives from the defective action of the feed pump, partly caused by the leakage of steam into the pumps, which prevented the water from entering them, and partly from the return of a large part of the water through the valves at the return stroke of the pump, in consequence of the valve lifting too high. ”