Chapter VII: Part 7

When pumps run very fast the piston speed is so high that the water cannot enter the pump fast enough to completely fill the cylinder and consequently a partial cylinder full of water is delivered at each stroke. _High speeds also increase slippage_, due to the _seating of the valves_. Fig. 191 represents a sectional view of the water end of a pump, showing the position of the valves during a quick reversal in the direction of the arrows, which illustrates the position of the valves corresponding to high speed. The valves in a pump, like almost every other detail in the operation of machinery, do not act instantaneously, but require time to reach the seats.

When pumps run at high speed the piston will move a considerable distance, while the valves are descending to their seats, and water flows back into the pump cylinder until the valves are tightly closed. The valves will remain in the raised position shown in Fig. 191 until the piston stops at the end of the stroke, and under high speed the piston will reach the position on the return stroke indicated by the dotted line _L_ by the time the valves are closed. The cylinder will be filled up to this point with water from the delivery chamber so that no vacuum can be formed until after the piston reaches this position. The volume of water that can be drawn into the cylinder must necessarily be represented by the cubic inches cf space, minus the quantity which flows back during the time the valves are closing. It will thus be seen that the actual volume of water discharged is considerably less than a cylinderful, and the difference, whatever it may prove to be, is called, and is due to slippage.

Fig. 190 represents the same pump running at a comparatively low speed. It will be noticed that the valves have not been raised as high as in Fig. 191, because a longer time being allowed for the discharge of the water, a smaller orifice is sufficient. It will be seen also that the piston, moving at a lower velocity, cannot travel as far in Fig. 190 before the valves seat, and consequently a vacuum can be created in the cylinder earlier in the stroke, and a larger volume of water can therefore be drawn in during the return stroke. In the latter case it is evident that the volume of water drawn into the cylinder will be nearly equal to a cylinderful and consequently the loss by slippage must be correspondingly less.

In order to reduce the loss by slippage several valves are used instead of a single valve of equal area. A flat disc valve will rise a distance equal to one-fourth the diameter of the port or of the opening in the seat to discharge the same volume of water that can flow through the port in the same time. In practice the rise exceeds this proportion of one-fourth a trifle, owing to the friction of the water, and this is especially true at high speeds.

_Reinforced pump valves._ Where pure gum has been used for pump valves it has always proved too soft and when it has been compounded with other substances it has been found too hard to withstand the severe duty to which it is subjected as a material for pump valves.

In the accompanying Fig. 192 is shown the Braden pump valve, which is made of _composition of rubber having wire rings embedded in the center of the disc_. The composition has been removed from a section to show these rings. A ferrule of composition metal forms a hub around the center through which the bolt or stud passes to guide the valve and to prevent excessive wear of the hole.

Its wire coil frame work clothed with rubber maintains a due amount of stiffness, with a degree of flexibility which prevents its bulging into the holes in the seats, or sticking therein, and thus impairing the suction and discharge. Both sides, the upper as well as the lower, are made available for service. These qualities of stiffness and flexibility combined, permit this valve to adjust itself to form a water-tight seat.

_Armored pump valves._ As represented in Fig. 193 this is a valve made by stamping a metal disc out of steel which is then plated with copper to protect the surface and secure the adhesion of the rubber. Marginal notches are left on the inside and outside edges of the plate and rubber is moulded around these, and vulcanized to the required hardness; a brass or copper plate may be used instead of steel and the plates may be corrugated radially to increase their stiffness when the area of the valve is large.

Experience proves that the water valve adopted together with its location, has a material bearing upon the efficiency of any pump; easy seating valves are subject to more or less slippage, owing to tardy seating; the location of water valves should be above the pump cylinder, inasmuch as in operation the pump is always primed, while if suction valves are placed below, any wear on the valves or valve seats, or obstruction under the valves, will cause the water to leak entirely out of the water cylinder, making it necessary to prime the pump before it can be started.

NOTE.—The screwed seat is shown in Fig. 194, Stud Fig. 195, Metal
Valve Fig. 196, Spring Fig. 197, and all put together in Fig. 198.

_Valve seats, bolts and springs_ should be of the best composition or gun-metal; and valves of composition, or hard or soft rubber, to suit the duty such pump is required to perform. These valve seats are screwed into the valve plate, and valves may be changed from composition to rubber by merely removing bolt, and substituting one for the other without removing the seat. This is of great advantage where a pump is to be used for hot water after being used for cold water.

_Air chambers_ are placed upon the top of a pump, see Figs. 199 and 200, and contain air for the purpose of introducing an _air cushion_ to counteract the solidity of the water, thus preventing shocks as the water flows through the valves; and also for the purpose of securing a steady discharge of water.

The water being under pressure in the discharge chamber, compresses the air in the air chamber during each stroke of the water piston and, when the piston stops momentarily at the end of the stroke, the air expands to a certain extent and tends to produce a gradual stopping of the flow of water, thus permitting the valves _to seat easily and without shock or jar_.

_The capacity of the air chamber_ varies in different makes of pumps from 2 to 3-1/2 times the volume of the water cylinder in single cylinder pumps, and from 1 to 2-1/2 times the volume of the water cylinder in the duplex type. _The volume of the water cylinder is represented by the area of the water piston multiplied by the length of stroke._

For single-cylinder, boiler-feed pumps and those employed for elevator and similar service the volume of the air chamber should be 3 times the volume of the water cylinder, and for duplex pumps, not less than twice the volume of the water cylinder. High speed pumps, such as fire pumps, should be provided with air chambers containing from 5 to 6 times the volume of the water cylinder.

The diameter of the neck should not exceed one-third the diameter of the chamber. When the pumps work under pressure exceeding 85 or 90 pounds per square inch, it is frequently found that the air gradually disappears from the air chamber, the air passing off with the water by absorption. In this case air should be supplied to the air chamber unless the pump runs at very low speeds, say, from 10 to 20 strokes for the smaller sizes and from 3 to 5 strokes per minute for pumping engines. At higher speed and with no air in the air chamber the valves are apt to seat heavily and cause more or less jar and noise, and the flow of water will not be uniform. The water level in the air chamber should be kept down to from one-fourth to one-third the height of the air chamber for smooth running at medium and high speeds.

NOTE.—In large pumping plants small air pumps are employed for
keeping the air chambers properly charged. In smaller plants an
ordinary bicycle pump and a piece of rubber tubing are used to good
advantage.

_Vacuum chambers_ are shown in Figs. 199, 200 and 201. These devices are attached to the suction pipe. When the column of water in the suction pipe of a pump is once set in motion, it is quite important, especially under high speeds, to keep the water in full motion, and when it is stopped, to stop it gradually and easily. This is accomplished by placing a vacuum chamber on the suction pipe, as shown in the figures.

The location of the vacuum chamber may be varied to suit the convenience of the engine room arrangements. Fig. 199 represents the vacuum chamber at the side of the pump, Fig. 200 shows it opposite the suction and Fig. 201 represents its position at the end of the pump.

_Vacuum chambers_ are practically of two designs, as shown in Figs. 202 and 203. The one shown in Fig. 203 should be placed in such position as to receive the impact of the column of water in the suction pipe. In order to do this effectively it should be placed in the position shown in Figs. 199, 200 or 201. The chamber illustrated in Fig. 202 is placed in the suction pipe below, but close to the pump.

_The action of the vacuum chamber is practically the reverse of that of the air chamber._ The object of the vacuum chamber is to facilitate changing continuous into intermittent motion. The moving column of water compresses the air in the vacuum chamber at the ends of the stroke of the piston, and when the piston starts the air expands (thus creating a partial vacuum above the water) and aids the piston in setting the column of water in motion again.

Thus the flow of water into the suction chamber of the pump is much more uniform during each stroke of the piston than without the vacuum chamber, and consequently the pump can be run at higher speeds without increasing the loss due to slippage and without “slamming” of the valves. Vacuum chambers should be slightly larger than the suction pipe and of considerable length rather than of large diameter and short. The size of the neck is substantially the same as in the air chamber.

PIPING A PUMP.

Fig. 204 on the opposite page represents the pipe connections, etc., of a pump with the delivery opening on the opposite side. D represents the _foot valve and strainer_ placed on the lower end of the suction, which should be not less than a foot from the bottom of the well; the distance named provides for the gradual filling of the well. C is the _suction pipe_ proper, screwed into _the elbow_, E, which changes its direction into the suction chamber, which contains _the strainer_, A. This strainer can be removed for cleaning by lifting _the bonnet_ secured by stud bolts on top. In connecting large pumps it is customary to attach a vacuum chamber, F, which in the absence of any regular pattern, may be made of a piece of pipe of the same diameter as the suction and screwed into a ^T^, instead of the elbow, E, with a regulation screwed cap on top as shown in the dotted lines.

A _priming pipe_ is shown by the letter J, often used to fill the pump on starting. The _discharge pipe_ connection is shown at G with the _air chamber attached_.

This figure is introduced for the purpose of showing an approved method of piping a pump. It may be observed that the flange joints in this design are so arranged that they may be disconnected without unscrewing any part of the suction pipe; this feature is almost essential in view of needed repairs.

The foregoing description of the parts of a pump relate to the water end solely; there remain the more complex and widely differing parts of the steam-end which constitute the distinguishing characteristics of the pumps built by the different makers. There remain also the particular parts belonging to the large pumping engines, air-pumps, etc.

These will be described under their respective chapters with much added and essential matter. Particular details as to the conditions of service under which it is proposed to operate pumps are to be found on the next page.

CONDITIONS OF SERVICE REQUIRED OF A PUMP.

It is especially important that the makers and also the sellers of pumps and pumping machinery should be informed regarding the proper type, size, pattern and _proportion of parts_ for any peculiar service, as well as to the plan of their connections and the kind of material to be used in their construction.

This information regarding the conditions of the service under which the pump is to be worked is quite pertinent to the foregoing pages regarding the parts of pumps. The following questions are extracted from the catalogue of an extensive manufacturer.

_First_—To what service is it to be applied?

_Second_—The quality of the liquid to be pumped, whether salt, fresh, acid, clear or gritty, and whether cold or hot?

_Third_—To what _height_ is the water to be lifted by _suction_, and what are the length and diameter of the suction and discharge pipes?

_Fourth_—Of what material is the suction pipe, and what is its general arrangement as regards other pipes leading into it, etc.?

_Fifth_—Will the supply be taken from a driven well? If not, from what source?

_Sixth_—To what height, or against what pressure, is the water to be pumped?

_Seventh_—What is the greatest quantity of water to be delivered per hour?

_Eighth_—What boiler pressure of steam is carried?

_Ninth_—Will the pump exhaust into the atmosphere, into a condenser, or against a back pressure? If the latter, how much?

BELTED PUMPS.

Fig. 205 represents an approved form of steam boiler feed pump, single acting. It has a crank shaft and a tight and loose pulley. It may be driven direct from any line shaft, a countershaft being unnecessary.

This is a compact form of a boiler feed pump; formerly the pump crank shaft was attached to floor beams or timbers above and connected by a long pitman to the pump which stood upon the floor; the objections to the older system of apparatus were found to be the vibration of the long pitman and the springing of the floors.

To obviate these two difficulties the pump and countershaft were attached to a post bringing them nearer together but finally resulting in the design of pump here shown. The broad base insures great stability in the operation of the pump especially when fixed to a rigid floor or timber foundation.

In the Table below are given some details furnished by the makers relating to six sizes of this style of pump, to which may be added that _the speed_ ordinarily used varies from 100 revolutions per minute for the small sizes, to 20 revolutions for the larger sizes.

TABLE.

===+=========+===============+================+=======+========
No.| Size |Suction fitted |Discharge fitted|Stroke.|Size
|piston. | for. | for. | |pulleys,
| | | | |in.
---+---------+---------------+----------------+-------+--------
1 |2 in.| 1 in. pipe| 1 in. pipe | 3 in. |16 × 4
2 |2-1/2 „ | 1 „ „ | 1 „ „ | 3 „ |16 × 4
3 |3 „ | 1-1/4 „ „ | 1-1/4 „ „ | 3 „ |16 × 4
4 |2 „ | 1-1/4 „ „ | 1-1/4 „ „ | 6 „ |18 × 4
5 |2-1/2 „ | 1-1/4 „ „ | 1-1/4 „ „ | 6 „ |18 × 4
6 |3 „ | 1-1/2 „ „ | 1-1/2 „ „ | 6 „ |18 × 4
---+---------+---------------+----------------+-------+--------

Fig. 206 exhibits two independent pumps. The description of the pump shown in Fig. 205 will apply to the left-hand pump which is _a boiler feed pump_. The improvement consists in the addition of another pump at the right-hand side; this is a _suction force pump with an air chamber_ and is used to draw water from a well and discharge it into a tank from which it is taken by the other pump and forced into the boiler, as occasion requires.

These two pumps work simultaneously, being driven from the same shaft with cranks set opposite each other. Like the pump previously described this has a tight and loose pulley. The larger sizes are geared, having a pinion on the pulley shaft and a spur wheel on the crank shaft.

These two pumps represent a high service and a low service, the left-hand pump working under high pressure, against that in the boiler and the right one against the head of water in the tank. Each pump has its own separate connections—one or more—to suit the required conditions.

The right-hand pump is double acting; the plunger-rod is guided by a steadiment which holds it in line and preserves this alignment and the power is transmitted through a forked connecting rod. The Table below refers to both these pumps.

TABLE.

===============================+=============================
BOILER PUMP. | DBLE.-ACTING FORCE PUMP.
---------+-----------+---------+-------+-----------+---------
Diam. | Suc. and | Gal. per| Diam. | Suc. and | Gal. per
cyl. | dis. | stroke | cyl. | dis. | rev.
---------+-----------+---------+-------+-----------+---------
2-1/2 in.| 1-1/4 in. | 1—8 | 3 in.| 1-1/2 in.| 2—5
2-1/2 „ | 1-1/4 „ | 1—8 | 4 „ | 2 „ | 4—5
---------+-----------+---------+-------+-----------+---------

In Fig. 207 is shown a double acting power pump used principally for feeding boilers but may be employed for any purpose in forcing water or other liquids against pressure. This pump is double acting, is made with four _check valves_, as shown in engraving, and will draw water through 25 feet of suction pipe. On a high lift like the foregoing a foot valve (as shown at D in Fig. 204) should be used.

The form of valves used in this type of pump are the regular commercial check valves, made of steam-metal, extra heavy; the valve proper is of the _wing_ pattern as shown in the small cuts. There are four of these wings on each valve, at right angles to one another forming a cross with arms of equal lengths.

The seat of the valve has an angle of 45° to which the valve is adjusted. A part of this valve projects above the top and has a slot, shown by the dotted line in it to receive the edge of a screw-driver, held in a bit stock to grind the valve seat in refitting. The lift of the valve is regulated by the distance between the top of the stem and the bottom of the covering nut or cap.

In hydraulic pumps it is found to be good practice to give the wings of these valves a twist, or pitch, so that the water in passing through will cause the valve to rotate and fall in a new position every time it comes in contact with the seat.

Fig. 208 represents a very compact design of _double acting low service belt driven pump_. The water cylinder is bored and has a piston fitted to it; both ends of this cylinder are covered with “heads,” one of which has a stuffing box through which the piston operates; the outer end of this piston rod is fitted to a slotted yoke which slides upon a guide at the bottom.

This mechanism, just described, takes the place of a pitman connection and occupies very much less space. The crank shaft is supported at each end in pillow blocks and is driven by a belt having a tight and loose pulley; larger sizes are geared. Access to the two sets of valves can be had by slacking up four nuts upon the long belts, two of which are shown in the engraving. The broad base secures great stability for this size pump.

Fig. 209 exhibits two _single acting plunger pumps_ actuated by one shaft having a crank upon each end with crank pins opposite to one another. This shaft is supported on the top of two pillars which form a part of the solid cast iron frame. The boxes are babbited. The crank shaft has a cast iron spur gear keyed to it and meshes into a pinion upon the pulley shaft. The teeth are cut to insure smooth and quiet running. The power is transmitted through a belt upon a tight and loose pulley. Each pump is secured to the frame by four bolts. The lower end of the pitman has an arrangement to take up the wear by means of two set screws with lock-nuts as shown in the figure on the top of each plunger. This pump is largely used as a boiler feed pump. These pumps can be used separately or together and with single or compound connections.

_Duplex Power Pump._ This engraving, Fig. 210, shows a special boiler feed pump having ball valves, as shown in section, and which is also intended for use in pulp mills and in other places where it is necessary to pump sandy or muddy water, or chemicals, soap and other heavy bodied liquids. These pumps have composition ball valves, composition plungers and composition lined cylinders and glands.

The two barrels or cylinders of this pump are brought together so as to occupy as little space as possible. Instead of cranks eccentrics are used having very large wearing surfaces. Each pitman has a ball at its lower extremity forming a “ball and socket” joint, which is adjustable to compensate for wear. All the bearings are Babbitted and like the last pump described the gears have cut teeth. It is belt driven.

_If there are two cranks as in the duplex power pump_ they are placed opposite to one another or 180° apart, the circle described by the crank-pin containing 360 degrees. _In the triplex pump_ this circle is divided into three equal parts of 120° each which is represented by the position of the cranks; _a quadruplex_ or two duplex pumps attached to the same shaft the cranks will be 90° apart. This arrangement effects a uniform distribution of load on the crank shaft and one of the pumps is continuously discharging at its maximum capacity.

This duplex _power_ pump should not be confounded with the “Duplex Pump” so called. The latter has two steam cylinders and two water cylinders and is double acting while the former is single acting.

The successful operation and durability of these, as of all power pumps, depends largely upon the judicious selection and application of a proper _packing to the stuffing boxes_. As for example, plaited flax dipped in a mixture of warm graphite and tallow, braided rawhide, Selden’s packing, etc., have proved by long service to have a _low co-efficient of friction_ and are not liable to cut the plungers.

_The triplex power gang pump_ is shown in Fig. 211. The engraving represents two triplex pumps bolted to one bed, and having an extended pulley shaft with pinions near each end to drive all of the pumps.

TABLE.

===========+========+========+========+========+========
No. | 1 | 2 | 3 | 4 | 5
-----------+--------+--------+--------+--------+--------
Size of | | | | |
Plunger | 2-1/4 | 3 | 4-1/2 | 6 | 8
in inches | | | | |
-----------+--------+--------+--------+--------+--------
Length of | | | | |
Stroke | 2-3/4 | 3-1/4 | 4-3/4 | 6-1/2 | 8-1/2
in Inches | | | | |
-----------+--------+--------+--------+--------+--------
Gallons | | | | |
per Stroke | .28 | .58 | 1.96 | 4·76 | 11.08
or 1 Rev. | | | | |
-----------+--------+--------+--------+--------+--------
Revolutions| | | | |
per |20 to 50|10 to 40|10 to 40|10 to 30|10 to 25
Minute | | | | |
-----------+--------+--------+--------+--------+--------
Size of | | | | |
Suction | 1-1/4 | 1-1/2 | 2-1/2 | 4 | 5
in Inches | | | | |
-----------+--------+--------+--------+--------+--------
Size of | | | | |
Discharge | 1-1/4 | 1-1/2 | 2 | 3-1/2 | 4
in Inches | | | | |
-----------+--------+--------+--------+--------+--------
Size of | ACCORDING TO DUTY REQUIRED
Pulleys |
-----------+--------+--------+--------+--------+--------
Geared | { *16 }| { *16 }| { *13 }| { *20 }| { *20 }
| { 72# }| { 80# }| { 71# }| { 89# }| { 80# }
-----------+--------+--------+--------+--------+--------
Pressure | 175 | 175 | 170 | 165 | 160
Pounds | | | | |
-----------+--------+--------+--------+--------+--------

* Teeth in Pinion. # Teeth in Spur Gear.

The description of the duplex power pump just given, applies to this type also. The exception is that _the triplex has three plungers and barrels_ instead of two. There are two spur wheels and two pinions on each pump to equalize the power to better advantage, as by this arrangement one eccentric is placed between each pair of spur wheels and two eccentrics outside. The pinion shaft is in one piece having tight and loose pulleys.

_The eccentrics_—six in number—are set at 60°, and an even strain on the belt at all points of the stroke is thus obtained, and connecting both discharges together insures a steady flow without shock. Where light duty only is required, these pumps are made without gears to run with the belt over pulleys.

Fig. 212 represents _a single acting triplex plunger pump_ actuated by a belt over a tight and loose pulley.

The principal characteristic of this pump is the long connecting rods. These have at their upper ends regular connecting rod straps with brasses fitted to them and adjusted by wedges and set screws. At the plunger or lower ends of these rods bronze bushings and steel pins are used.

These pumps are largely employed for pumping semi-liquids such as tar, soap, mud, tan-liquor, oils, chemicals, sewage, etc.

The teeth of the pinion and the meshing part of the two gears are protected by _a shield_ to prevent clothing being caught or parts of the body from being injured.

For these various materials different valves are necessary to be used each suited to the substance to be elevated or conveyed.

The removal of one cover, in this pump, exposes all the discharge valves and a plate uncovers each of the three groups of suction valves, as shown. The suction pipe may be attached at either end of the suction chamber while the discharge pipe may be connected with one or both ends of the discharge chamber.

The pump here represented has barrels 8-inch in diameter by 10-inch stroke. The air chamber is very large in proportion to the pump.

TABLE.

===============+=============+==================+======+==========
PLUNGERS |Capacity one | SIZES OF PIPE | | Tight
---------------+Revolution of+--------+---------+Geared|and Loose
Diameter Stroke| Crank Shaft |Suction |Discharge| | Pulleys
---------------+-------------+--------+---------+------+----------
4 in. 4 in.| 0·65 gals. | 3 in. | 3 in. |5 to 1|20 × 3 in.
4 „ 6 „ | 1· „ | 3 „ | 3 „ |5 to 1|20 × 3 „
5 „ 6 „ | 1·5 „ | 4 „ | 4 „ |4 to 1|20 × 4 „
5 „ 8 „ | 2· „ | 4 „ | 4 „ |4 to 1|20 × 4 „
7 „ 8 „ | 4· „ | 5 „ | 5 „ |4 to 1|30 × 5 „
8 „ 10 „ | 6·5 „ | 6 „ | 6 „ |5 to 1|36 × 6 „
8 „ 12 „ | 7·8 „ | 6 „ | 6 „ |5 to 1|36 × 6 „
---------------+-------------+--------+---------+------+----------

_The Deane single acting triplex power pump_ is shown in Fig. 213. Pumps of this type are used for general service in places where a large quantity of water is to be obtained in a short time and delivered under high pressure; they are adapted for tank service, water works, boiler feed, etc.

The pillar, or column design of frame is employed in this pump which secures great strength with the least weight of material, and at the same time is accessible for adjustment or repairs. The bearings for both the steel shafts are unusually long, which reduces the pressure per square inch below the factor of safety and increases the durability. The crankpins are set 120 degrees with one another so that the strokes successively overlap, which promotes an easy flow of water through the delivery pipe. The crank shaft is of the composite design, the center crank pin is of equal diameter and forming a part of the shaft, with discs and crank pins attached to each end by shrinking fits and keys. Either disc, crank, or their crank pins, can be duplicated without sacrificing any other part, which in itself is a great advantage.

The connecting rods have solid ends with adjustable boxes, with adjustment by means of wedge and screws. The brasses are lined with a special anti-friction metal bored to exact size.

The crossheads are of the box design with adjustable shoes having large wearing surfaces in bored guides. These guides are secured to the frame by studs and nuts.

The plungers are outside packed, the cylinders are submerged, thus keeping the pump primed at all times. The plungers are bolted to the crossheads and are readily removed when necessary. The cylinders are single acting and are cast separate from the base and other parts of the machine, so that repairs can be made at small cost, and, furthermore, should it be desirable to use the pump for moving liquids which would be injurious to cast iron, cylinders of other metals are substituted. The water chest is cast separate from the cylinders and is provided with large handholes, affording easy access to the interior and to the valves for inspection and cleaning. The handholes are located so that one valve may be removed independent of the others.

Improved grease cups are placed on all the bearings. This pump is very popular with the users of power driven pumps and is generally selected for high pressures and for hot or gritty water. Its simplicity of design and construction, together with the convenient arrangement of working parts, renders it desirable in isolated places where little attention is given to any kind of pumps.

Fig. 214 represents the Gould triplex single acting power pump and is one of many designs of this class of power pumps. The frame consists of two standards, which contain the two end cylinders, and the seats to which the outside crosshead guides are bolted. These are held together by two castings, one containing the center crosshead guide, and the other the center cylinder. The crankshaft is a solid steel forging, while the bearings are of phosphor bronze, and the pinion shaft bearings Babbitted.

The gear wheels are machine cut, the pinion and the adjacent teeth of the large gear are covered by suitable guards.

The crossheads are provided with adjustable shoes or gibs, which work in bored guides. The connecting rods are fitted with straps and bronze boxes, which are adjustable for wear by means of wedge and set screws, the wristpin brasses being of the marine type. The cylinders are provided with bronze liners, which are readily removable when necessary for repairs, the plungers being ground to size, present a smooth polished surface to resist the wear.

The valve boxes are separate castings, and each contains a set of suction and discharge valves. These valves are rubber discs, held firmly against the bronze seats by cylindrically wound springs. All of these pumps are furnished with air chambers, and vacuum chambers are provided when the nature of the service demands it. All valves and other working parts of the pump are accessible for inspection, cleaning and repairs, all internal parts being arranged within easy reach through the large handholes.

The pumps here shown are intended for moderately light pressures as for example not to exceed 150 lbs. per square inch, but they are also made in heavier proportions for very high pressures (5,000 lbs. to 15,000 lbs.) such as is necessary to operate hydraulic presses, draw benches for brass and copper tubing and that class of work.

A very simple automatic regulator and by-pass connection (shown in the chapter on accessories) can be attached to these pumps in situations where a constant pressure is to be maintained and allow the pump to run continuously at its maximum speed. This regulator is adjusted to open the by-pass valve whenever the pressure in the compression tank or pipe system exceeds the limit pressure, and so fills the office of a safety valve by allowing the surplus water to return to the tank.

_The Riedler belt driven pump_ is shown in Fig. 215.

The principal feature of this pump is its valve; there is but one valve for the suction and one for the discharge, which greatly simplifies the pump end. When working against high pressures, the ordinary rubber or leather faced valves are oftentimes pounded to pieces, but in this pump, on account of the mechanical control, the valves work well under all pressures.

This valve and valve seat are circular in form, and made of bronze, as shown in Fig. 216. The valve has a lift of from 1 to 2 inches, and an area sufficiently large to reduce the velocity of the water flowing through it to a few feet per second.

At the beginning of the stroke the valve opens automatically, controlled, however, by a very simple and effective mechanical device, and it remains open practically during the entire stroke. When near the end, it is positively closed at the proper moment by the controller.

This valve, see Fig. 216, may be briefly described as follows. The seat, A, is turned to slip into its place in the pump and is made tight by a round rubber hydraulic packing, B, in a groove near the bottom. A spindle or stud, C, in the center of this seat supports and guides the valve, D, which is made tight by a leather seal, E. The rubber collar or buffer spring holds the valve above its seat, and this valve unlike ordinary pump valves, always remains open except when pressure is brought to bear to close it. The valve bonnet, G, also forms the bearing for the valve stem with fork, which spans the spindle, C, at one end and having the valve lever and pin, H, for operating at the other end. The valve stem is made tight by a stuffing-box and gland as shown. The operation of this valve is substantially as follows.

At the beginning of the suction stroke the valve is opened by the rubber spring, F, the pressure upon the collar being relieved by lifting of the valve fork arms through motion of the eccentric.

It will be observed from an inspection of Fig. 215 that both the suction valve and the discharge valve are controlled by an eccentric—rock arm—and valve levers similar to the motion of _Corliss_ valves.

As the plunger nears the end of its stroke and before it starts on the return stroke, the valve fork closes the valve, and thus prevents slip and avoids pounding, so common in pumps having valves that close by their own weight. In case of any obstruction between the valve and its seat the rubber buffer spring will be compressed thus preventing all injury to mechanism.

The lost work expended in closing the valves is hardly worth any consideration as it is practically the friction only of the eccentric and the members of the valve gearing, the bearings of which are all small.

The motion for these valve gears is usually taken from an eccentric on the main shaft.

The standard speed of the Riedler pumps is about 150 revolutions per minute. Smaller pumps run even faster than this.

It may be desired to connect a pump directly to a high speed electric motor or water wheel already installed. To meet these conditions, a special design known as the Riedler Express pump, is built.

The chief feature of this pump, is its suction valve. This valve is concentric with, and outside of the plunger, and lifts in the opposite direction to that of the plunger when on its suction stroke. At the end of the suction stroke, the plunger presses the valve to its seat, thus making it certain that the valve is seated when the plunger starts on its delivery stroke, allowing practically no slip. A high air suction chamber containing a column of water is placed immediately before the suction valve, so it is certain that the pump will fill as the plunger moves. Ordinarily the pump would not completely fill, owing to the high speed of the plunger.

These pumps are also built with steam cylinders both of the plain slide valve and Corliss designs.

THE ELECTRIC
PUMP

ELECTRICITY AND ELECTRICAL MACHINERY.

Each kind of power requires its own special machinery so constructed and adapted as to utilize it; hence, to be serviceable to mankind, electricity demands machinery suited to its nature; what that is, will be indicated in the following few paragraphs.

Electricity is a name derived from the Greek word _electron_—amber. It was discovered more than 2,000 years ago that amber when rubbed with a Fox’s tail possessed the curious property of attracting light bodies. It was discovered afterwards that this property could be produced in a dry steam jet by friction, and in A. D. 1600 or thereabouts, that glass, sealing-wax, etc., were also affected by rubbing, producing electricity.

Whatever electricity is, it is impossible to say, but for the present it is convenient to consider it as a kind of invisible something which pervades all bodies. While the nature and source of electricity are a mystery, and a constant challenge to the inquirer, many things about it have become known—thus, it is positively assured that electricity never manifests itself except when there is some mechanical disturbance in ordinary matter, and every exhibition of electricity in any of its multitudinous ways may always be traced back to a mass of matter.

NOTE.—The great forces of the world are invisible and impalpable; we
cannot grasp or handle them; and though they are real enough, they
have the appearance of being very unreal. Electricity and gravity are
as subtle as they are mighty; they elude the eye and hand of the most
skillful philosopher. In view of this, it is well for the average man
not to try to fathom, too deeply, the science of either. To take the
machines and appliances as they are “on the market,” and to acquire
the skill to operate them, is the longest step toward the reason for
doing it, and why the desired results follow.

Electricity, it is also conceded, is without weight, and, while electricity is, without doubt, one and the same, it is for convenience sometimes classified according to its motion, as—

1. _Static electricity_, or electricity _at rest_.

2. _Current electricity_, or electricity _in motion_.

3. _Magnetism_, or electricity _in rotation_.

4. _Electricity in vibration._

Other useful divisions are into—

1. _Frictional_ and

2. _Dynamical_,

And into—

1. _Static_, as the opposite of

2. _Dynamic electricity._

There are still other definitions or divisions which are in every-day use, such as “vitreous” electricity, “atmospheric” electricity, “resinous” electricity, etc.

_Static Electricity._—This is a term employed to define electricity produced by friction. It is properly employed in the sense of a static charge which shows itself by the attraction or repulsion between charged bodies. When static electricity is discharged, it causes more or less of a current, which shows itself by the passage of sparks or a brush discharge; by a peculiar prickling sensation; by an unusual smell due to its chemical effects; by heating the air or other substances in its path; and sometimes in other ways.

_Current Electricity._—This may be defined as the quantity of electricity which passes through a conductor in a given time—or, electricity in the act of being discharged, or electricity in motion.

An electric current manifests itself by heating the wire or conductor, by causing a magnetic field around the conductor and by causing chemical changes in a liquid through which it may pass.

NOTE.—_Statics_ is that branch of mechanics which treats of the
forces which keep bodies at rest or in equilibrium. _Dynamics_ treats
of bodies in motion. Hence static electricity is electricity at rest.
The earth’s great store of electricity is at rest or in equilibrium.

_Radiated electricity_ is electricity in vibration. Where the current oscillates or vibrates back and forth with extreme rapidity, it takes the form of waves which are similar to waves of light.

_Positive Electricity._—This term expresses the condition of the point of an electrified body having the higher energy from which it flows to a lower level. The sign which denotes this phase of electric excitement is +; all electricity is either positive or,-, negative.

_Negative Electricity._—This is the reverse condition to the above and is expressed by the sign or symbol-. These two terms are used in the same sense as _hot_ and _cold_.

_Atmospheric electricity_ is the free electricity of the air which is almost always present in the atmosphere. Its exact cause is unknown. The phenomena of atmospheric electricity are of two kinds; there are the well-known manifestations of thunderstorms; and there are the phenomena of continual slight electrification in the air, best observed when the weather is fine; the aurora constitutes a third branch of the subject.

_Dynamic Electricity._—This term is used to define current electricity to distinguish it from static electricity. This is the electricity produced by the dynamo.

_Frictional electricity_ is that produced by the friction of one substance against another.

_Resinous Electricity._—This is a term formerly used, in place of negative electricity. The phrase originated in the well known fact that a certain (negative) kind of electricity was produced by rubbing rosin.

_Vitreous electricity_ is a term, formerly used, to describe that kind of electricity (positive) produced by rubbing glass.

_Magneto-electricity_ is electricity in the form of currents flowing along wires; it is electricity derived from the motion of magnets—hence the name.

_Voltaic Electricity._—This is electricity produced by the action of the voltaic cell or battery.

_Electricity itself is the same thing, or phase of energy, by whatever source it is produced_, and the foregoing definitions are given only as a matter of convenience.

ELECTRO-MOTIVE FORCE.

The term is employed to denote that which moves or tends to move electricity from one place to another. For brevity it is written E. M. F.; it is the result of the difference of potential, and proportional to it. Just as in water pipes, a difference of level produces a pressure, and the pressure produces a flow so soon as the tap is turned on, so difference of potential produces electro-motive force, _and electro-motive force sets up a current so soon as a circuit is completed for the electricity to flow through_. Electro-motive force, therefore, may often be conveniently expressed as a difference of potential, and _vice versa_; but the reader must not forget this distinction.

In ordinary acceptance among engineers and practical working electricians, electro-motive force is considered as pressure and it is measured in units called volts. The usual standard for testing and comparison is a special form voltaic cell, called the Clark cell. This is made with great care and composed of pure chemicals.

The term _positive_ expresses the condition of the point having the higher electric energy or pressure, and, _negative_, the lower relative condition of the other point, and the current is forced through the circuit by the (E. M. F.) electric pressure at the generator, just as a current of steam is impelled through pipes by the generating pressure at the steam-boiler.

Care must be taken not to confuse electro-motive force with electric force or electric energy, when matter is moved by a magnet, we speak rightly of magnetic force; when electricity moves matter, we may speak of electric force. But, E. M. F. is quite a different thing, not “force” at all, for it acts not on matter but on electricity, and tends to move it.

THE DYNAMO, OR GENERATOR.

The word dynamo, meaning power, is one transferred from the Greek to the English language, hence the primary meaning of the term signifying the electric generator is, the electric power machine.

The word generator is derived from a word meaning birth giving, hence also the dynamo is the machine generating or giving birth to electricity.

Again, the dynamo is a machine driven by power, generally steam or water power, and _converting the mechanical energy expended in driving it, into electrical energy of the current form_.

To summarize, the dynamo-electric generator or the dynamo-electric machine, proper, consists of five principal parts, viz:

1. _The armature or revolving portion._

2. _The field magnets_, which produce the magnetic field in which the armature turns.

3. _The pole-pieces._

4. _The commutator or collector._

5. _The collecting-brushes_ that rest on the commutator cylinder and take off the current of electricity generated by the machine.

Fig. 218 shows a dynamo of the early Edison type—the names of the principal parts are given in the note below, as well as those of the other parts of the machine.

_This is a two-pole machine_, direct current; the figure is introduced to show the “parts” only—as this dynamo has been largely superseded by others of the four pole type.

NOTE.—A, Magnet yoke; B, Magnet and field piece; C, Pole piece;
D, Zinc field piece; E, Armature; F, Commutator; I, Quadrant; JJ,
Brushes; K, Adjusting handle for the brushes; L, Switch pivot; M,
Pilot lamp receptacle; N, Negative lug; O, Switch lever; P, Positive
lug; Q, Positive terminal; R, Negative terminal; S, Negative rod; T,
Pole piece; UU, Bearings; X, Slides for belt tightener; VVV, Driving
pulley; Y, Connecting blocks, one on each side of machine.

_An electric motor_ is a machine for converting electrical energy into mechanical energy; in other words it produces mechanical power when supplied with an electric current; a certain amount of energy must be expended in driving it; the _intake_ of the machine is the term used in defining the energy expended in driving it; the amount of power it delivers to the machinery is denominated _its out-put_.

The difference between the out-put to the intake is the real _efficiency_ of the machine; it is well known that the total efficiency of _an electric distribution system_, which may include several machines, usually ranges from 75 to 80 per cent., at full load, and should not under ordinary circumstances fall off more than say 5 per cent. at one-third to half load; the efficiency of motors varies with their size, while a one horse-power motor will, perhaps, have an efficiency of 60 per cent., a 100 horse-power may easily have an efficiency of 90 per cent. and the larger sizes even more.

The general and growing application of electric power to the driving of all kinds of machinery including pumps makes _the question of motor driving one of the most important in the power field_. For many purposes, a single speed is sufficient, but for others, it is imperative that the speed should be variable; and for still others, though not absolutely necessary, a speed adjustment is very desirable.

While the _direct-current motor_ has been in this field so long that its properties are well known and its possibilities fully developed, in the operation of motors located in the immediate neighborhood of the generator the _alternating-current motor_ has marked advantages where a large area of territory has to be covered and the conditions are nearly uniform, that is to say—

Where the current has to be transmitted a long distance and the load is approximately constant, the alternating system is preferred, as it can be operated with small main lines or conductors. This effects a saving in copper, over the direct system which requires larger conductors.

Fig. 217, on page 247, shows _a four-pole generator_ designed to run by a belt or directly connected to an engine. The five parts named, as the principal parts of a dynamo, are all shown in the figure. The machine is arranged ready to be bolted to the floor.

Fig. 219 on the opposite page is the _armature_ which is made up of coils of insulated wire, the free ends of which, see Fig. 220, are united to the arms of the _commutator bars_. When the armature is finished, as shown, the wire forms an unbroken circuit.

Fig. 221 is intended to represent another form of armature, but the principle upon which it operates, is the same, as the other shown. A A, represents the wire coils of the armature, B, is the shaft with its journals, C, is the commutator. All commutators both for generators and for motor armatures are insulated by mica between the bars.

Fig. 222 shows _a woven wire brush_. The brushes on the dynamo, page 247, are made of carbon.

Fig. 223 shows an alternating _induction_ motor. Induction is a property by virtue of which an electric current is transferred from one conducting line to another _without any metallic connection_; it is that influence by which a _strong current_ flowing through a conductor controls or affects _a weaker current_ flowing through another conductor in its immediate neighborhood,—the strong current remaining unaffected.

Fig. 224 exhibits the armature for the above alternator; it is familiarly called a “squirrel cage armature” on account of its resemblance to the wheel in a squirrel’s cage.

Its peculiar construction enables it to run without producing any sparks; this feature renders it safe to run where there are explosive gases which might be ignited by an electric spark. In the machine the bearings are cast solid with the end shields, thus assuring perfect alignment when properly turned. Another feature is the automatic self adjusting bearings which are lubricated mechanically by rings resting upon the shaft. These rings were formerly a failure, but by the use of mineral oils are now a success.

This machine is one of the simplest designs of alternating motors, the example, Fig. 223, is one developing one hundred horse-power.

Fig. 225 shows a revolving _field_ with “spider.” In this construction of generators or motors the field revolves in place of the armatures, the first object of this design is to reduce the high rotative speed; it is also claimed to have a better electrical efficiency.

The field spider consists of an extra heavy cast iron pulley which is keyed to the shaft; the low speed at which it runs permits the employment of bolts to secure the field coils and laminated pole pieces to the rim of the spider, as shown in the engraving. With this construction each individual pole piece can be removed and replaced independent of the others.

_The laminated pole piece_, one of which is shown in detail in Figs. 226-229, takes its name from the fact that it is built up of a large number of layers of soft sheet iron, which it has been demonstrated give a better electrical efficiency than a solid iron. Soft iron is the most magnetic of all metals and is better suited for pole pieces than steel.

It should be understood that each individual pole piece is insulated from the others as well as from the spider. The pieces of sheet iron are stamped out—like washers and are cut apart and the ends united so as to form a continuous coil, like a coil of wire and each coil is isolated; mica is used between the layers.

Fig. 230 is designed to illustrate the front of a continuous current two wire switchboard with circuit breakers; these are made up usually of marble or slate so that they will not burn; the Insurance Underwriters require a non-combustible material at this place, as well as hangers, and insulators used for conductors.

_The Switches_ shown in the middle of the board, are enlarged in Fig. 232, and are used for closing the connections with the generators and lines running to various parts of the field to be lighted or furnished with power.

The switch handles are made usually of wood or hard rubber; the blades are of copper. The connections are soldered into the sockets shown upon the ends of the screws which project beyond the back of the switch-board.

The upper row of figures as shown in Fig. 230 and enlarged in the engraving, 231, are _circuit-breakers_. The use of these is analogous to that of the safety-valve upon a steam boiler, so that when the pressure in the circuit exceeds that at which it is set the “breaker” opens the circuit and thus prevents damage.

In this case, the main contact is formed by means of a laminated brush while the final stroke is made on carbon, the motion of this breaker is by means of a toggle-joint which so multiplies the power applied that it does not require much of an effort to close it; this device maintains the same speed in operating the breakers when the circuit-breaker is tripped.