Suction pump

“ These suction pipe sizes, although larger than common for trade pumps of the same size, are believed to be amply justified by experience, and exert a powerful influence toward enabling the pump to run smoothly at high speed with water cylinders filling perfectly at each stroke. No defect is more common than restricted suction pipes. ”

“ Men sometimes ask why, (if they can run a pump smoothly so as to get a delivery of 1,000 gals. per minute,) we should not accept as “a thousand gallon pump,” irrespective of its suction valve area or its exhaust port area or the size of its cylinders.
To this we reply that when new and favorably set almost any pump built according to these specifications can run at a much greater delivery than here rated, but when lift is unusually high or suction pipe long, or when the pump takes its suction under a head, no pump can be run so fast as on, for instance, a 5-foot lift. ”

“ Fig. 163 represents a widely used type of suction pump, it is designed for vessels of not more than fifteen to twenty feet deep; for contractors who wish to pump large quantities of water from excavations, etc.; for irrigation or any other purpose where a compact and capacious pump is desired.
The lever may be worked from three different points as shown by lugs on the illustration. The lever socket is made at such an angle that the bent wrought iron lever when put in one side up, is right for ordinary pumping and by simply changing it the other side up, it becomes a vertical lever. ”

“ If the combined length of suction and discharge pipe is more than 50 feet, the speed must be increased to overcome friction.
Before starting, prime the pump so that suction pipe and pump are filled with water.
Warm water can only be raised by suction to moderate heights, and if very hot it must flow to the pump. To prevent freezing in cold weather, drain by unscrewing plug provided in the bottom of the pump shell. ”

“ A suction pump would do the work of six men, but I have not seen such an innovation as a pump in all this land. In making a cart the native will take his ax and hew him out one complete, and there will be no particle of iron about it. ”

“ Should the pump operator, however, through a mistaken idea of the proper method of operation, think that the priming should be continued until all air was exhausted from the suction pipe and the pump running in normal condition, there would be some by-passing between chambers, but as there is a free vent for the air, the main result would be simply to limit the amount of air exhausted per stroke, from the main suction, by the amount of water which entered a chamber in this way. ”

“ The revolutions will, of course, correspondingly increase, and under all ordinary conditions a pump should run smoothly at this higher capacity though a little more vibration and pounding would be expected than when running simply at its rated speed.
After cushion valves are adjusted there should be no noteworthy water hammer or valve-slam. Sometimes valve-slam is not the fault of the pump, but arises from an obstructed suction pipe. It is objectionable to doctor water hammer in a pump by “snifting” air into the suction, as this cuts down the efficiency and is a poor expedient. ”

“ If the suction pipe is of gas-tube, the sockets must all be taken off, and a paint of boiled oil and red-lead be put on the screwed end, then a string of raw hemp bound round and well screwed up with the gas tongs, making a sure joint for cold water, steam, or gas.
Many plumbers prefer lead pipe, so that they can make the usual plumbers’ joint. The tail m of the pump is for fixing the suction pipe on a plank level with the ground. Stages n are fixed at every 12 ft. ”

“ If this is true, tighten up the pump plunger stuffing-box nut a little. If now the pump starts off well, you have found the difficulty; but at the first opportunity you ought to repack the stuffing-box.
If the stuffing-box is all right, examine the supply suction hose. See that nothing is clogging the strainer, and ascertain whether the water is sucked in or not. If it is sucked in and then is forced out again (which you can ascertain by holding your hand lightly over the suction pipe) , you may know something is the matter with the first check valve. ”

“ Whether a foot valve is used or not, a strainer should be attached to the suction pipe to prevent large substances from entering, that might choke or clog the pump, but be careful that suction area is not contracted. ”

“ Pressure gages were connected to the suction, discharge, and condenser inlet, as shown at G, G' and G'' respectively. When No. 1 unit was operating alone the gage G showed practically zero, indicating no vacuum in the suction pipe. Observing the same gage when No. 2 unit was running, a vacuum as high as 2 pounds was indicated, showing that No. 2 was drawing more than its share of cooling water from the main A and hence the circulating pump for No. 1 was fighting for all it received. ”

“ This dredger is 220 ft. by 40 ft. by 17 ft. 2 in., and has a hopper capacity for 1250 tons of dredgings. The buckets have each a capacity of 25 cub. ft., and are able to raise 1000 tons of ordinary material per hour. The suction pump, which is driven by an independent set of triple expansion engines, is capable of raising 700 tons of sand per hour, and of dredging to a depth of 35 ft. below the water-line. The lower end of the suction pipe is controlled by special steam appliances by which the pipe can be brought entirely inboard. ”

“ When we suck or pump, it seems to us as if the liquid was drawn up, and so we use the word draw in regard to it. So, too, we talk about the suction or drawing power. But, as I have showed you, the liquid is pushed up instead of being drawn. All that the piston in a pump does is to make room. It does not draw the water into that room, but the pressure of the air forces it in. Whenever there is any room made, the air is always ready either to go in itself or to force something else in. ”

“ No pump however good will lift hot water, for the reason that as soon [Pg 92] as air is expelled from the barrel of the pump the vapor occupies the space, thereby destroys the vacuum and interferes with the supply of water. When necessary to pump hot water, place the pump below the supply, so that the water will flow into the valve chamber. Always have a strainer at lower end of suction or supply pipe. A pump should be set up so that it is accessible for inspection, cleaning and repairs, and so that the shortest and straightest suction and delivery pipes can be used. ”

“ For such situations, a steam ejector connected to the suction pipe near the pump is advised, and may be required in addition to the regular priming pipes and tank. The size of the ejector should be sufficient to exhaust the suction pipe within about three minutes. Such ejectors will be considered as extras not included in the ordinary pump fittings. ”

“ Table 54 shows the capacities of some diaphragm pumps as rated by the manufacturers. The smaller sizes are the more frequently used and are equipped with a 3–inch suction hose with strainer and foot valve. They are not adapted to suction lifts over 10 to 12 feet. Where greater lifts are necessary one pump may discharge into a tub in which the foot valve of a higher pump is submerged.
259
Fig. ”

“ A foot valve must of necessity generally be located where it is inaccessible for quick repairs, and as they grow old, foot valves are often a source of trouble. Where a suction pipe is exposed even slightly to frost, a foot valve is specially objectionable.
A priming tank is provided for the purchaser in all cases where there is ever to be any lift on the suction. It is generally advised that this tank have a capacity of one-half of what the pump can throw at full speed in a minute. This means 250 gallons for a 500-gallon pump and 500 gallons for a 1,000-gallon pump, etc. ”

“ Another reason might be that the pump lowers the suction supply, thus increasing the lift until there is not sufficient speed for the elevation. If the pump works indifferently, delivering a stream obviously too small, it is generally because the pump was not properly primed and some air remains in the top part of pump shell. Unless primed by steam ejector, the pet cock or plug found on top of pump shell should always be open while priming, and the pump must not be started until water flows out of same. ”

“ A pump with horizontal top discharge and short length of discharge pipe is sometimes difficult to start, especially if suction lift is high, owing to the fact that the water is thrown228 out of the pump shell before the water in the suction pipe has got fairly started, thus allowing air to rush back into the pump. ”

“ Now suppose the plunger to move to the right, and as no more air can get into the pump, that already within it will expand, and will therefore become lighter, hence there will be less pressure on the surface of the water within the suction pipe than there is on the outside of it, and as a result the water will rise up the pipe, not because the plunger draws it, but because the air outside the pipe presses it up within the pipe. ”

“ 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. ”

“ A hydraulic dredge consists mainly of a centrifugal pump with its driving engine and boiler, and hoisting machinery for handling suction pipe and boat; the pump in operation creates a strong suction flow in the suction pipe, sufficient to pick up the material and draw it into the pump, from which it is again delivered through the discharge pipe any distance to point of delivery, and can at same time be elevated to reasonable heights. Sand, mud, silt, etc., are readily picked up by the suction force only, but where material is packed it must first be agitated. ”

“ Next to light, the most important creature comfort is water and plenty of it. The most common causes of failure lie with the pump itself. If one of the deep well type gets out of adjustment, repairing it is a professional job and unless you are unusually expert, don't attempt it. Telephone for a plumber or handy man. But with the shallow well pump, you can, in a pinch, replace the leathers that make the valves exert the proper suction. ”

“ The Marsh Steam Pump is so constructed that the exhaust steam may be turned into the suction, thereby condensing its exhaust steam and returning it with its heat to the boiler, thus heating the feed water to a high degree.
The pump is automatically regulated and can never run too fast to take suction, or should the water supply give out when the throttle valve is wide open no injury can occur to the moving parts. ”

“ 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 clear then, that however high the pump may be above the level of the water, the water cannot rise more than 34 feet up the suction pipe, even though all the air be excluded from it and a perfect vacuum formed, because the propelling force, that is, the atmospheric pressure, can only raise a column of water equal in weight to itself, and it is found in practice to be an unusually good pump that will lift water thirty feet. ”

“ If you place the hand on one of the open ends and exhaust the air, by attaching the long tube of the pump to the other you cannot remove the hand easily. Do not try to pump the air out entirely, as the suction may be too strong and draw blood. It is by the rarefaction of the air that the cupping-glass is applied to people who require bleeding. ”

“ When the vacuum in the cylinder becomes great enough to overcome the weights attached to the auxiliary piston, it rises, allowing vacuum to reach the main piston, which is drawn up and the suction valve closed. When this valve is closed the vacuum in the pump at once starts to build up to the maximum possible for the pump to produce, and if the pump used is of the piston type the vacuum will run up to nearly 28 in., resulting in the pump’s taking the least power on which it can be operated. ”

“ When the trench or ditch is too deep for the pulsometer to lift the water to the surface of the ground by suction, the truck can be run out on planks over the ditch, when the pump can be lowered to the necessary suction distance from the water. Suitable lengths of steam hose, with universal couplings, suction hose, also suitable lengths of light flanged galvanized pipe for the discharge, which can be readily connected may be carried on the truck, proper brackets being provided for their reception. ”

“ The valves in the discharge pipe were closed and steam admitted to the ejector, the pump being still and no water in the gauge glass on the pump casing, which must be full before the pumps will work. The suction pipe of the ejector is only two and a half inches in diameter, the steam pipe one inch in diameter. To fully charge the pumps at this point required filling the pump casing and the suction pipe containing about 2,000 gallons ”