HAND PUMPS.
Thetheoretical action ofa pump has already been described and illustrated;—thepractical operationis described in the note below. The subject is important enough to justify the space it takes to present these two descriptions of the action of a pump.
Fig. 156.
Fig. 156.
The parts of which a pump is composed are: 1,the barrel or cylinder; 2,the plunger or piston; 3,the valves; 4,the pipes.
The barrel of a modern pump is a tube of metal having a water tight plunger or piston which moves freely up and down at the pleasure of the operator. This plunger is in its simplest form made of cast iron in two parts. The upper part consists of an arched part having a hole in its center to receive a bolt which passes through it and a jaw on the lower end of the pitman or connecting rod. The upper end of this pitman is attached to the pump handle by means of a bolt. 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. If this is not the case, however, as it is when the water level from which the pump obtains its supply is below the pump itself, there being a partial vacuum produced, the atmospheric pressure forces the water into the space displaced by the plunger or piston, continuing its flow until the end of stroke is reached.The water then ceases to flow in, and the suction valve of the pump closes, forbidding the water flowing back the route it came. The piston or plunger then begins to return into the space it has just vacated, and which has become filled with water, and immediately meets with a resistance which would be insurmountable were the water not allowed to go somewhere.(See next page.)Its only egress is by raising the discharge valve by its own pressure, and passing out through it. This discharge valve is in a pipe leading to the boiler, and in going out of the cylinder by that route the water must overcome boiler pressure and its own friction along the passages. Water is inert and cannot act of itself; so it must derive this power to flow into the feed pipe and boiler from the steam acting upon the steam piston of the pump. The steam piston and pump piston are at the two ends of the same rod. Therefore the steam pressure exerted upon the steam piston will be exerted upon the pump piston direct.
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. If this is not the case, however, as it is when the water level from which the pump obtains its supply is below the pump itself, there being a partial vacuum produced, the atmospheric pressure forces the water into the space displaced by the plunger or piston, continuing its flow until the end of stroke is reached.
The water then ceases to flow in, and the suction valve of the pump closes, forbidding the water flowing back the route it came. The piston or plunger then begins to return into the space it has just vacated, and which has become filled with water, and immediately meets with a resistance which would be insurmountable were the water not allowed to go somewhere.(See next page.)
Its only egress is by raising the discharge valve by its own pressure, and passing out through it. This discharge valve is in a pipe leading to the boiler, and in going out of the cylinder by that route the water must overcome boiler pressure and its own friction along the passages. Water is inert and cannot act of itself; so it must derive this power to flow into the feed pipe and boiler from the steam acting upon the steam piston of the pump. The steam piston and pump piston are at the two ends of the same rod. Therefore the steam pressure exerted upon the steam piston will be exerted upon the pump piston direct.
Between the upper and lower parts of the plunger a cup leather is introduced before these parts are screwed together. This cup leather, while it allows the plunger to move freely, also makes a water-tight joint.
The lower valve consists of a piece of cast-iron flat on the bottom and circular in shape about three-eighths inch thick with a curved toe at one side. This iron disc is secured to the flat leather valve by a screw that passes through the valve and is threaded in the disc.
Fig. 157.
Fig. 157.
The object of this toe upon the disc is to open the lower valve by means of raising the pump handle as far as it will go which lowers the plunger upon the toe and tips the lower valve upon its seat. This same operation also lifts the valve in the plunger off its seat, so that all the water in the barrel drains back into the well so the pump is kept from freezing up in winter.
Fig. 158.
Fig. 158.
The leather which forms the lower valve is held in place by clamping the pump barrel upon it, so that it is held between the barrel and the base plate.
Hand pumps are primarily divided into: 1, suction or lift pumps; 2, force pumps, and 3, suction and forcing pumps; 4, also pumps for exhausting air from vessels.
Of the first class, the common single-acting house-pumps shown in Figs. 157 and 158 are examples; the pumps are simply modifications of the suction-pump; a common form of lift-pump has a pitman-rod which pushes the water up instead of lifting it through a spout at or near the top of the cylinder.
The details of the suction-pump are as follows—at the bottom of the cylinder is a pipe communicating with the liquid to be raised, and a valve which opens from beneath. A similar valve is placed in the piston.
A force-pump is shown in Fig. 159; from the two figures the difference between the lift and the force-pump may be understood; while the former raises the liquid above its piston from which it flows under no pressure, the latter forces it out of the barrel under a varying pressure which depends upon circumstances. When the piston rises the suction valve opens, and the valve in the piston closes by the air-pressure. The liquid then enters the barrel beneath the piston. On the descending stroke the suction valve closes, and the liquid flows upward into the discharge pipe.
Fig. 159.
Fig. 159.
In Fig. 160 is shown an air-chamberattached to a force-pump for the purpose of preventing shocks in the discharge, and for producing a steady flow; air-chambers are also frequently attached to suction pipes for a similar purpose.
According to the underlying principles of action thus far explained hundreds of thousands of pumps have been constructed and operated. It is beyond the limits of this volume—or any single book to give the names and details of these so-called “hand-pumps,” however, three approved styles are shown in Figs. 161, 162, 163.
Fig. 161 represents adouble acting force pumpused extensively on ship-board, wharves, around factories, mills, etc., and in residences, for tank pumping. On ships these pumps perform the three-fold purpose of filling boilers when cold, washing down decks and to satisfy government inspection as to fire protection; in service in mines they are unaffected by mine water, the working parts being made non-corrosive. It is claimed that a three-inch diameter cylinder with a stroke of four and a half inches with a 11⁄4-inch suction pipe and 1-inch discharge pipe will lift and force water 150 ft. high and has a capacity of ·28 gallons for each stroke, with the water not more than twenty-five feet below the pump.
Fig. 160.
Fig. 160.
Fig. 162 representsa two cylinder force pump; this has vertical single acting pistons actuated by one lever, producing the same results as a double-acting pump. It is claimed that the total lift and force, from supply to point of delivery, withthe pump not more than twenty-five feet above water will attain one hundred feet; that a 3-inch × 4 inch cylinder, 11⁄2-inch suction and 11⁄4-inch discharge will deliver ·24 gallons of water for each stroke.
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. The valves are accessible and removable by hand from above. It is claimed that with 81⁄2-in. diameter cylinder and 6-in. stroke that the capacity is 147⁄100gallons for each stroke, with 20 feet lift—the suction pipe being 3-in. in diameter.
Fig. 161.
Fig. 161.
In the illustrations (Figs. 161 and 162) it will be noticed that the discharge is conveniently arranged to receive either fire hose, or iron pipe connections for other uses, as in mines and on ship-board.
Being made in large factories, there are immense numbers in world-wide use; every detail of these pumps is carefully considered; the sizes manufactured range from 2 inches to 6 inches diameter of cylinders, with strokes 4, 41⁄2and 5 inches.
The capacityof each pump is also given in the published lists by the makers; this is given under the heading “Capacity per Revolution” with the added information as to the best sizes to be used for the suction and discharge pipes.
Fig. 162.
Fig. 162.
Note.—It were well for the student to know that in case of breakage or worn out parts of an otherwise serviceable apparatus that the makershave provided for their repairsas will be indicated by the following taken from the catalogue of a well known manufacturer. “In the following lists will be found descriptions of pieces for all the staple pumps, which will prove of decided convenience. In this connection we desire to impress most emphatically on the minds of dealers that the threads are cut to exact and accurate gauges; all holes in flanges, etc., drilled to templets; all castings made from exact metal patterns, similar parts being always the same. Therefore, repairs will invariably take the place of the broken parts.”
Note.—It were well for the student to know that in case of breakage or worn out parts of an otherwise serviceable apparatus that the makershave provided for their repairsas will be indicated by the following taken from the catalogue of a well known manufacturer. “In the following lists will be found descriptions of pieces for all the staple pumps, which will prove of decided convenience. In this connection we desire to impress most emphatically on the minds of dealers that the threads are cut to exact and accurate gauges; all holes in flanges, etc., drilled to templets; all castings made from exact metal patterns, similar parts being always the same. Therefore, repairs will invariably take the place of the broken parts.”
Fig. 163 represents a Pitcher Spout Pump, of large size for contractors, and Fig. 164 the parts of a common house pump. The two figures show pumps substantially the same.
Fig. 163.
Fig. 163.
The smallest size “listed” of this pump has a cylinder diameter of 21⁄2inches, fitted with 11⁄4in. pipe and it has a capacity of ·09 gal. per stroke and it takes more than eleven strokes to pump a single gallon. With a cylinder 41⁄2inches, with pipe 11⁄2in. diam., the pump has a capacity of ·34 gal. per stroke.
Fig. 164.
Fig. 164.
The engraving 164 shows a pitcher pump dissected, in which A represents the lever or handle, B the plunger which contains the discharge valve and is made tight by a cup leather packing, C is the fulcrum for the lever, D the barrel or cylinder, E the lower or suction valve, F the base which supports the pump. The leather which forms the valve E also makes the joint between the cylinder and the base.
Fig. 165 represents aTwo-Cylinder Suction and Force Pumparranged with extension levers. When these levers are put in place, they afford room for a large force of men to work, renders this pump a most powerful engine for throwing water on fires, or supplying it for many uses about factories, warehouses, wharves, etc.
The discharge hose can be fitted both ends for wrought-iron pipe or either end for hose. The Table below gives the makers’ numbers, the diameter of the cylinders, etc., and also distance to which the water can be lifted or forced.
Fig. 165.
Fig. 165.
TABLE OF SIZES, CAPACITIES, ETC.
No.DiameterCylinderStrokeCapacityper Rev.DischargeSuction*Lift andForce43in.61⁄2in.·40gal.11⁄4hose in.11⁄2pipe in.100ft.631⁄2„61⁄2„·54„11⁄2„2„75„84„8„·87„2„21⁄2„75„1041⁄2„8„1·10„2„21⁄2„75„125„8„1·36„2„21⁄2„75„166„7„1·96„21⁄2„4„50„
*Total lift and force from supply to point of delivery, Pump not more than 25 feet above water.
Fig. 166 representsa hand, rotary force pumpprovided with a balance wheel. A sectional view of this pump is given in Fig. 167; these pumps are adapted for almost any place or purpose where lift or force pumps can be used, they can be moved to any place where water is within suction distance and immediately operated.
Fig. 166.
Fig. 166.
The provision of a foot valve at the end of the suction pipe will keep it always filled.
In the rotary pump there are no pistons.As will be seen in theFig. 167, there are two pinions of extremely coarse pitch meshing into one another with neat fit in the case; the joints become practically air-tight by the water which surrounds them and passes through the case.
Fig. 167.
Fig. 167.
Both pinions are supported by a journal at each end, the shaft of one being extended to receive a pulley or hand wheel as shown in Fig. 166, hence, one pinion causes the other to revolve. The teeth on the bottom side of the pinions move away from each other and form a partial vacuum which the water fills and is carried around between the teeth of the pinions on opposite sides and is discharged through a central opening in the case at the top, thence through the discharge pipe into the tank or reservoir.
In the small sizes of the rotary pump there is no trouble from leakage, until the parts become much worn.
Fig. 168.
Fig. 168.
Bag Pump.This is a form of bellows-pump in which the valve disc A, which takes the place of the bucket, is connected with the base of the barrel by an elastic bag distended at intervals by rings. This bag may be made of leather or of double canvas. The upper end of the bag should be firmly tied with a cord in a groove gouged out of the rim of the board at A. Into this board is fixed the fork of the piston rod, and the bag is kept distended by a number of wooden hoops or rings of wire, fixed to it at a few inches distance from one another, and kept at equal distances by three or four cords binding them together and stretching from the top to the bottom of the bag. Now let this trunk be immersed in the water: it is evident that if the bag be stretched from the compressed form which its own weight will give it by drawing up the piston rod, its capacity will be enlarged, the valve A will be shut by its own weight, the air in the bag will be rarefied, and the atmosphere will press the water into the bag. When the rod is thrust down again, the water will come out at the valve A, and fill part of the trunk. A repetition of the operation will have a similar effect; the trunk will be filled, and the water will at last be discharged at the spout.
Fig. 169.
Fig. 169.
Bellows-pump(Page 186). This is an atmospheric pump in which the part of the piston is played by the top leaf of the bellows. A verysimple method of describing an invention, from which great good in drainage of waste lands in Europe, was realized. “There was of course a valve covering the interior orifice of the nozzle and opening outwards, to prevent the air from entering when the upper board was raised. This valve is not shown because the art of representing the interior of machines by section, was not then understood, or not practiced. The lower board is fastened to the ground by a platform while the suction pipe dips into the water. A weight is placed on the upper board to assist in expelling the water.”
Fig. 169 represents aDouble Lantern Bellows-Pumpas used in the 16th century. This engraving is plain and requires no description. Fig. 170 shows a diaphragm pump in which a sheet of rubber or its equivalent is used as a substitute for a piston in a cylinder.
Fig. 170.
Fig. 170.
Note.—When an ox or a horse plunges his mouth into a stream, he dilates his chest and the atmosphere forces the liquid up into his stomach precisely as up the pipe of a pump. It is indeed in imitation of these natural pumps that water is raised in artificial ones. The thorax is the pump; the muscular energy of the animal, the power that works it; the throat is the pipe, the lower orifice of which is the mouth, and which he must necessarily insert into the liquid he thus pumps into his stomach. The capacious chest of the tall camel, or of the still taller cameleopard or giraffe, whose head sometimes moves twenty feet from the ground, is a large bellows-pump which raises water through the long channel or pipe in his neck. The elephant by a similar pneumatic apparatus, elevates the liquid through that flexible “suction pipe,” his proboscis; and those nimble engineers, the common house-flies, raise it through their minikin trunks in the manner of the gigantic animals which in remote ages roamed over this planet, and which quenched their thirst as the ox does. There could have been none which stood so high as to have their stomachs thirty feet above the water they thus raised into them.
Note.—When an ox or a horse plunges his mouth into a stream, he dilates his chest and the atmosphere forces the liquid up into his stomach precisely as up the pipe of a pump. It is indeed in imitation of these natural pumps that water is raised in artificial ones. The thorax is the pump; the muscular energy of the animal, the power that works it; the throat is the pipe, the lower orifice of which is the mouth, and which he must necessarily insert into the liquid he thus pumps into his stomach. The capacious chest of the tall camel, or of the still taller cameleopard or giraffe, whose head sometimes moves twenty feet from the ground, is a large bellows-pump which raises water through the long channel or pipe in his neck. The elephant by a similar pneumatic apparatus, elevates the liquid through that flexible “suction pipe,” his proboscis; and those nimble engineers, the common house-flies, raise it through their minikin trunks in the manner of the gigantic animals which in remote ages roamed over this planet, and which quenched their thirst as the ox does. There could have been none which stood so high as to have their stomachs thirty feet above the water they thus raised into them.
Rope Pump.This machine consists of one or more endless ropes, all stretched on two pulleys as shown in Figs. 171 and 172. These pulleys have grooves formed in their surfaces for the reception of the ropes. A rapid rotary motion is communicated to the upper pulley, by a multiplying wheel, and the ascending side of each rope carries up the water absorbed by it, and which is separated from it while passing over the upper pulley, partly by centrifugal force, and partly by being squeezed in the deep groove.
Fig. 171.
Fig. 171.
Fig. 172.
Fig. 172.
In the beginning of the motion, the column of water adhering to the rope, is always less than when it has been worked for some time, and continues to increase till the surrounding air partakes of its motion. By the utmost efforts of a man, nine gallons of water were raised by one of these machines from a well, ninety-five feet deep, in one minute. (Adam’s Philos.)
The hydraulic beltis a similar contrivance. It is an endless double band of woolen cloth, passing over two rollers, not here shown. It is driven with a velocity of not less than a thousand feet per minute; when the water contained between the two surfaces is carried up and discharged as it passes over the upper roller, by the pressure of the band. Some machines of this kind are stated to have produced an effect equal to seventy-five per cent. of the power expended, while that of ordinary pumps seldom exceeds sixty per cent. (Lon. Mechan. Mag.)
Spray Pump.Fig. 173 exhibits a carefully designed pump made to spray trees, plants, etc. All the working parts are of brass, the valves are metal; the air chamber is made of galvanized iron or copper and has large capacity. It will hold sufficient compressed air to keep the spray going from six to ten minutes after the pumping stops. The “agitators” are placed so that they keep the liquid thoroughly stirred. The plungers can be easily removed and packed without the necessity of taking the pump to a shop.
Fig. 173.
Fig. 173.
The pump is fastened to the bottom of the barrel by a bolt passing through the barrel and secured by a nut underneath, with packing to prevent leakage, and by an iron plate at the top covering the opening through which the pump is placed in the barrel. This pump is arranged with one, or two levers, and for one or two lines of discharge hose. The cylinders are 21⁄2inches diameter with stroke 3 inches; its capacity per stroke is 0·13 gal.
Combined Pump and Horse Power.The “horse power” (apparatus) with its “pole” for one horse and two poles for two horses and its wrought iron “tumbling shaft” has been so modified that a horse operates the pump, by means of a “sweep,” direct connected to the pump crank shaft.
The animal will make three to four circuits per minute, giving the pump crank shaft a speed of 40 to 50 revolutions per minute. The capacity of a 4 in. plunger and 8 in. stroke is given as 3·120 gallons per hour; the suction pipe is given as 31⁄2in. diam. and the discharge as 3 in. pipe.