N. Hawkins

PUMP SPEED GOVERNORS.

The speed at which a pump is operated is a matter of more or less importance, according to its widely varying conditions. In all calculations regarding the capacity of a pump the regularity with which it makes its “stroke” is taken into consideration; the uniformity of the supply of water to a boiler is always a subject of anxiety to the attendant. The capacity of a pump is usually determined by its number of strokes in a given time, hence the need of a pump regulator or governor.

The governor is not only intended to maintain a uniform water pressure in the mains, but to prevent the pump from racing whenever a greater quantity of water is demanded than the pump is capable of delivering, as in the case of bursted mains or hose, or any other contingency whereby the pressure upon the discharge pipe is suddenly relieved.

Examples of pump governors or regulators follow.—

The Mason Pump Governor. This pump governor, shown in Figs. 566 and 567, is attached directly to the rock arm of the pump, and operates a balance valve placed in the steam pipe, thereby exactly weighing the pressure of steam to the needs of the pump. As all the working parts are immersed in oil, the wear is reduced to a minimum.

The Mason governor consists mainly of a cylindrical shell, or reservoir, as shown in sectional view, filled with oil or glycerine. The plunger, A, is connected with the arm, I, to some reciprocating part of the pump and works simultaneously with the strokes of the pump, thereby drawing the oil up through the check valve, DD, into the chambers, JJ, whence it is forced alternately through the passages, BB, through another set of check valves into the pressure chamber, EE. The oil then runs through the orifice, C, the size of which is controlled by a key inserted at, N, into the lower chamber, to be re-pumped as before. In case the pump or engine works more rapidly than is intended the oil is pumped into the chamber, EE, faster than it can escape through the outlet at, C, and the piston, GG, is forced upward, raising the lever, L, with its weight, and throttling the steam. In case the pump runs more slowly than was intended, a reverse action takes place, the weight on the end of the lever, L, forces the piston, GG, down and more steam is admitted. As the orifice at, C, can be increased or diminished by adjusting the screw at, N, the governor can be set within reasonable limits to maintain any desired speed. The piston, GG, fits over the stationary piston, forming an oil dashpot, thereby preventing dancing of the governor. This dashpot is fed from the pressure chamber, E, through a passage which is controlled by an adjusting screw, K, which is set with a screwdriver, after removing the cap screw, T. It requires no further attention after being once adjusted.

For duplex pumps up to 2-inch steam pipe, inclusive, this governor is fitted with a duplex valve, which prevents the escape of oil from the pressure chamber through the orifice, C, and thereby prevents the steam valve from opening wide during the momentary pause of the pump piston.

This governor should be placed on the pump at some point where the requisite motion can be obtained for operating it, and also in such a way that a rod can be run from the knuckle joint on the top lever, I, to the valve in the steam pipe, as shown in the engraving. Place the valve in the pipe, so that the stem shall be in a direct line with the knuckle joint on the lever, and pull out the valve stem to its full extent. With the ball on the governor in its lowest position, connect the valve rod to the lever. The governor is then ready to be filled with oil. Remove the plug on top of the gauge glass, and fill the governor about half full with a good, clean, light grade of mineral oil. The governor is then ready to work.

Start the pump at about its maximum speed; place the key in the keyhole on the side of the governor and turn to the right until the speed of the pump has diminished slightly. Open the throttle valve wide, and the pump will be under full control of the governor. Should there be much dancing or fluctuation of the ball, remove the screw, T, insert a small screwdriver, and screw the adjusting screw in, at K, until the irregular motion ceases. After the governor has run a little while, it will be found that the oil in the glass gauge has dropped considerably. It should then be refilled, so that the glass will be about half full when the governor is at work. Under no circumstances should the gauge be full, as too much oil will prevent the ball from coming down and opening the valve when the steam pressure falls. As there is no glass pressure upon the glass gauge the governor may be filled while in motion by removing the plug on the top of the gauge.

The Mason elevator pump pressure regulator. This regulator, illustrated in Fig. 569, is designed for use in connection with the larger sizes of steam pumps operating hydraulic elevators. Its important feature is in operating on the slightest change of pressure opening to its fullest extent and closing the steam valve promptly and positively.

Referring to sectional view, Fig. 570, the operation of this valve is as follows: steam from the boiler enters the regulator at the inlet, indicated by the arrows and passes through into the pump, which continues in motion until the required water pressure is obtained in the system, and through a ¹/₄-inch pipe connected to, A, acts upon the diaphragm, B. This diaphragm is raised by the excess water pressure, and carries with it the weighted lever, F, opens the auxiliary valve, D, and admits the water pressure from the connection, E, to the top of the piston, at the same time opens the exhaust ports under the piston, and allows the water under the piston to escape into the drip pipe, thereby pushing the piston down, closes the steam valve and stops the pump.

As soon as the pressure in the system is slightly reduced, the lever, F, on account of this reduced pressure under the diaphragm, is forced down by the weight, carries with it the auxiliary valve, D, opens the exhaust to the top of the piston, and also admits water pressure under the piston, which is forced up and opens the steam valve, and starts the pump.

The speed controlling device of the style A governor shown in Fig. 571 is simple and can be so set as to prevent the pump from racing, regardless of the drop in water pressure. Surrounding the upper end of the valve stem is a coiled spring, which acts as a cushion for the valve and stem, and by the use of a spring, the stem can be quite small thus reducing the friction in the stuffing-box to a minimum. The tension of this spring is sufficient to firmly seat the valve, but if excessive pressure is exerted on the piston, which is often the case when two or more pumps are connected to the same mains, the spring will be compressed and will allow the sleeve to slide down on the stem, thus relieving the valve of the increased strain, which would be liable to injure it or buckle the stem.

The regulating hand wheel remains cool, and can be manipulated without injury to the hands. The regulation is very simple, and is quickly adjusted by simply turning the wheel to the right or left, to increase or decrease the pressure. No locking device is necessary, as the wheel will remain in any set position.

The cylinder will not become coated with lime, but will retain its smooth surface over which the piston travels, insuring free action, with no leakage around the piston. The drip is located at the extreme upper travel of the piston, so as to retain sufficient water in the cylinder to prevent any air from coming in contact with leather piston packing. This arrangement insures a tight piston as the leather packing will remain soft and pliable and at the same time the water serves as a lubricant for the interior of the cylinder.

The hand wheel can be placed in different positions and all that is necessary to make the change is to take out the bolts and move the regulating hand wheel to the desired position. By this arrangement the engineer can set the hand wheel regardless of the arrangement of the steam piping.

All sizes, including 1¹/₂-inch and smaller, are made as shown in style B, Fig. 572, and are not provided with an automatic speed controlling device. This style is made especially for boiler feed pumps and for supply pumps for the street system of hot water heating. They are also fitted with a special valve for pumps working under very high steam and low water pressure.

The finished parts of these Carr steam pump governors, Figs. 571 and 572, are nickel plated.

The valves and seats in these governors and regulators are renewable, Fig. 573. The tools necessary to remove the seats are a wrench and a flat piece of iron wide enough to span the lugs on top of the upper seat. The upper seat is threaded and screwed into the upper opening in the valve chamber. The lower valve seat is fitted into the lower opening, a steam-tight fit, but is free to move sufficiently to compensate for the expansion of the valve.

The bridges, which unite the valve seats, contain about an equal quantity of metal, and are of equal length with the post that binds the valve discs, thus compensating for the expansion and contraction of the metal and insuring a perfectly tight valve, regardless of the temperature of the steam.

The Holyoke Improved Speed Governor for water wheels is shown in Figs. 574 and 575. The following is a description of the two figures where the same letters are used to designate the parts appearing in both illustrations:

The pulley, A, is the receiving pulley, and is designed to run at 400 revolutions per minute, receiving its power from the water-wheel shaft, or countershaft belted from the same.

Contained in the pulley, A, are the two governing weights, BB, of which the centrifugal forces are overcome by the springs, CC. The varying motions of the governing weights, BB, are transmitted through racks and pinions in the hub of pulley, A, to levers, K and L, which operate the valve, N, admitting water under a light pressure to the cylinder, O. The water is admitted to the cylinder, O, through ports at either end, causing the piston to move forward or backward, governed by the movement of the governing weights, BB.

The pulley, A, is keyed to the main shaft, and at the opposite end is keyed a bevel pinion running in mesh with a bevel gear on either side, all of which are contained in the gear-case, P. These gears cause the clutch discs, D, to run in opposite directions. In each disc is a clutch, E, keyed to a shaft, transmitting power to the pinion, S, running in mesh with the spur gear, R, which is loose on the shaft, J, and transmits its power through the pin clutch, T, to gate shaft, J. The gate shaft, J, is connected by a pair of bevel gears to the shaft and hand wheel, Q.

The motion of the piston rod, I, caused by the movement of piston in cylinder, O, is carried by the lever, G, to the clutch shaft, F, by means of the pivoted nut at V. The clutch shaft, F, operates either clutch, E, corresponding to the movement of the governing weights, BB, caused by the variation in speed. From the clutch thus engaged, the power is carried by the clutch shaft, F, through the gears, S and R, and the pin clutch, T, to the gate shaft, J.

The governor is provided with a steadying device operated by the chain, H. The gate shaft, J, is designed to make four, six or eight turns to open the gate, four being the regular number.

The receiving pulley and governor gate shaft may revolve in either direction, as desired.

The receiving pulley is designed to run at 400 revolutions per minute, and is driven by a 4-inch double belt.

The governor gate shaft may be arranged to open the gates in four, six or eight turns, and may be extended on either or both sides of the governor to meet the necessary requirements.

The governor is capable of exerting a pressure ranging from 25,000 to 50,000 foot pounds on the governor gate shaft.

The advantages claimed for this improvement on the Lombard governor are thus stated:

1. It requires only a light water pressure to handle the heaviest gates.

2. It is simple in construction. All parts are easy of access.

3. There are no pumps working under high pressure.

4. There are no dash pots to get out of adjustment, due to the change in temperature of oil, etc.

5. There is but one belt on this machine.

6. All parts which are constantly in motion are equipped with ring-oiling bearings.

Fig. 576 is an illustration of the mechanism necessary to raise and lower the head gates which are used to admit and regulate, also to shut off the water supply from pond or lake to the flume conveying it to the wheel. In this case there are two head gates having racks upon the upright timbers connecting with the gates. Two shrouded pinions engage these racks, which are keyed upon a shaft having a large spur wheel at its end, as represented. A pinion upon a second shaft engages this spur wheel which in turn has also a spur wheel which engages a pinion upon the crank shaft having two cranks opposite one another. By means of these cranks with two to four men upon each crank the gates are operated very satisfactorily. These shafts and gears are mounted upon heavy cast iron brackets bolted to the floor. Altogether it forms a very massive piece of mechanism.

The Utility combination pump governor is shown in the figure below. This mechanism may be bolted on any tank or receiver where the water level is to be automatically maintained. It consists of a closed pocket containing a float, A, which rises and falls with the water level inside the tank.

When the water rises above the desired level the float opens the throttle valve and starts the pump, and when it subsides the float falls and shuts off the steam.