US2546963A - Float gate - Google Patents

Description

April 3, 1951 c. M. BLACK 2,546,963

l FLOAT GATE i Filed Sept. 5, 1946 VKQTEFT/f/T CHA/waff? 5MM-WALL /2 r 2,3 /4 ANAL 111111111111 1 l 1 1 l l 1 l l 1 l l r l 1 l 1 11111111111 ATTORNEY Patented Apr. 3, 1951 UNITED STATES PATENT FFICE (Granted under the act of March 3, 1883, as

3 Claims.

amended. april 30, 1928;

The invention described herein may be manufactured and used by or for the Government of the United States for governmental purposes without the payment to me of any royalty thereon, in accordance with the provisions of the act of April 30, i928 (Ch. 460, i5 Stat. L. 467).

This invention relates to the art of controlling `the flow delivered by a centrifugal pump, or the like, above the pump and below the surface ofy a body of water subject to variations in surface level; and to means such as a float gate for this purpose.

In many installations it is desirable to have an outlet above a pump or pumps for discharge pipes thereof emptying into a canal or reservoir so that the total head against which the pumps have to operate may be a minimum in order to reduce power costs, and also in case a pump ceased to operate for any reason, as due to shutdown, power failure, or the like, to prevent the' water in the canal from being lost through backflow down the discharge pipe of the pump. A centrifugal pump without power, for example, will reverse due to pressure in its discharge line and allow considerably more water to return down the discharge lpipe than the pump can deliver.

While it is common practice for a pump outlet pipe to be arranged to discharge above the high water surface of a canal, for example, this requires that the pump be always operated against the maximum head, even for low water surface elevations in the canal, with a consequent waste of power. Also, a concrete outlet in the form cf a Siphon discharging under the low water level in the canal, with an electrically or otherwise controlled air vent to break the Siphon when the pump shuts down, may be provided to obtain an economical use of power,

but this results in a high first cost due to the A large amount of reinforced concrete required.

Objects of the invention are to improve the efficiency of installations of the class described; to provide an installation of the class described having an improved construction and relative arrangement of parts; and also to provide an inexpensive and reliable outlet into a canal or other body of water for the discharge pipe of one or more centrifugal pumps, or the like, which will discharge beneath the water surface in the canal and will automatically prevent the loss of water due to backflow through the discharge pipe when any or all of the pumping units are shut down.

rl`he features of the invention are shown in the accompanying drawing, wherein:

Fig. l is a diagrammatic view of a centrifugal pump connected to discharge below the surface level of a canal through an improved outlet, the pump being shut down and the outlet closed; and

Figs. 2 and 3 are diagrammatic views showing the controlled outlet under different conditions of flow.

The apparatus shown in Fig. l comprises a centrifugal pump it having a discharge pipe il extending above the pump and emptying into a suitable channel l2 disposed in a body of water, such as a canal I3. This channel comprises like side walls it connected by a bottom wall lli. These parts are so arranged that water delivered by pump lll issues from discharge pipe il into the channel below the low water surface level in the canal.

For controlling the flow through channel l2 there may be provided a buoyant iloat gate il disposed in the channel and mounted to pivot about a substantially horizontal axis, as by means of a transverse pin i8 extending between side walls iii of the channel. This is a radial float gate having a hollow body comprising like substantially sector shaped side walls I9 joined by a substantially straight and continuous bottom wall 2i and an arcuate valve member 22. Preferably the hollow body is closed by a top wallv 2S extending between the side Walls and the valve member, thus providing a watertight chamber inside the gate.

In Fig. 1, the pump is not operating, the canal is full of water and pump discharge pipe ll is empty. Gate il remains at rest since the water pressure on the curved surface of valve member 22 acts through pin is without producing a rotating force on the gate and the weight of the gate pulls it down.

In Fig. 2, the pump is operating and water flows from the pump discharge pipe beneath the gate and out into the canal. The height of the water at A is slightly higher than at C in the canal, since a loss oi' head occurs at B due to the restriction in the area of the water passage. The buoyancy -provided by the water-tight chamber in the gate supports that part of the weight of the gate not carried by pin i8. These two forces govern the depth of flotation of the gate and hence the amount of restriction and the head loss at B.

In Fig. 3, the motor driving centrifugal pump I 0 has been shut off, the direction of the rotation of the pump has reversed and water has just started to ow back down the pump discharge pipe. The height of the water in the canal at C remains the same, a head loss occurs at i31 and the height of the water at Al drops to less than that at C, due to the head loss at B1 and the outflow or" water back down the pump discharge pipe. The gate starts vto close due to the lower water surface at A1, further restricting the water passage and increasing the head loss at B1 which lowers the water surface at A1 still more and causes the gate to continue closing. The action is self-sustaining and the gate will dropl until closed.

The pin I8 of the gate should be placed at a short distance above the maximum water surface for best results, and seals should be provided at the down-stream side and `bottom of the gate for water-tightness when closed. The gate should also be placed far enough down stream from the end of the pump discharge pipe to permit free atmospheric pressure to occur here. This aids the back flow or" water dow-n the pump discharge pipe and also prevents any vacuum forming beneath the float gate, due to the action or the ivater owing down the pump discharge pipe, with a resulting extremely violent closure of the gate caused. by atmospheric pressure on its upper side. For optimum conditions of operation oi iicat gate, it should be possible for unrestricted iiow of .waterto occur down the pump discharge pipe as just described.

I claim:

l. The combination with a centrifugal pump, a discharge conduit therefor, and a channel for conning water in a stream between the discharge conduit and a body of water subject to variations in surface level such as water in a supply canal or reservoir, said discharge conduit being arranged to discharge above the pump and into the stream connned in said channel below the high water surface level of the body ci water subject to variations in surface level, of a buoyant substantially radial gate for controlling the flow ofthestream in said channel between the discharge conduitrand the body of water, means for mounting Saidgate for pivotal motion about a substantially horizontal axis disposed above and in Yrelatively close proximity to the maximum surface level of said body of water, said gate comprising a substantially arcuate valve member spaced from said axis toward said body ci water and asubstantially straight continuous Surface extending between said axis and the lower edge of said valve member for riding on and coacting with water beneath said gate.

2. rEhe combination with a centrifugal pump, a discharge conduit therefor, and a channel for confining water` in a stream between the discharge conduit and a body of water subject to variations in surface level such aswater in a supply canal or reservoir, said discharge conduit being arranged to discharge above the pump and into the stream confined in said channel below the high water surface level of the body of water subject-to variations in surface level, of a buoyant substantially radial gate for controlling the ow ofthe stream in said channel between the discharge conduit and the body of water, means for mounting said gate for pivotal motion about a substantially horizontal axis disposed above and in relatively close proximity to the maximum surface level oi said body of water, said gate comprising a substantially arcuate valve member spaced from said axis toward said body of water, means for subjecting water on the other side of said axis t0 atmospheric pressure, and a substantially straight continuous surface extending between said. axis and the lower edge of said valve member for riding on and coacting with water beneath said gate.

3. The combination of a channel open to atinosphere for conducting a stream or water between a pump discharge conduit and a body of water subject to variations in surface level, such as water in a supply canal or reservoir, a buoyant substantially radial gate for controlling iiow through said channel, means for mounting said gate for pivotal motion about a substantially horizontal axis disposed across said channel at an elevation adapted to be a short distance above the maximum surface level of said body oi water, said axis being spaced from the end oi the channel adjacent the pump discharge conduit to subject water in this portion of the channel to atmospheric pressure, said gate comprising a valve member spaced from said axistoward the end of saidA channel adjacent said body of water, and a substantially straight continuous surface extending between said axis and the lower edge of said valve member for riding on and coa-:ting with water beneath said gate.

CHARLES M. BLACK,

No references cited.

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