US3692430A

US3692430A - Liquid pumping system

Info

Publication number: US3692430A
Application number: US154554A
Authority: US
Inventors: John W Timmons
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-06-18
Filing date: 1971-06-18
Publication date: 1972-09-19
Anticipated expiration: 1989-09-19

Abstract

A system for pumping liquid as the liquid is being drawn from a dispensing line of the system by a pump having a prescribed pumping rate. The system is so constructed that the pump will stay on continuously while the liquid is being drawn from the system despite the fact that the pump is pumping the liquid at a greater rate than the liquid is being drawn through the dispensing line.

Description

iltiite Sttes etet Timmons [45] Sept. 19, 1972 1541 HQ :3 PUMPING SYSTEM 3,547,559 12/1968 Tittmann ..417/3o0x 72 Ive h wmm ,45 3,343,217 9/1967 Daubenberger ..417/311x 1 n f; 3,103,891 9/1963 Fulton m1. ..417/300 22 Filed: June 18, 1971 211 App1.No.: 154,554

Primary Examiner-William L. Freeh Assistant Examiner-Frank McKenzie Attorney-Kimmel, Crowell & Weaver [57] ABSTRACT A system for pumping liquid as the liquid is being drawn from a dispensing line of the system by a pump having a prescribed pumping rate. The system is so constructed that the pump will stay on continuously while the liquid is being drawn from the system despite the fact that the pump is pumping the liquid at a greater rate than the liquid is being drawn through the dispensing line.

1 1 2 Drawing Figures PRESSURE TANK PATENTEDSEP 19 m2 WATER? .32 PRESSURE VIZ Y TANK PUMP .20 MOTOR FIG. 1

FIG. 2

INVENTOR JOHN W T/MMONS BY KM,M z MW A 7' TORNEYS LIQUID PUMPING SYSTEM In liquid pumping systems, it is conventional practice to pump the liquid by a motor driven pump that pumps the liquid at a constant rate which is usually greater than the rate at which the liquid is being drawn from the system. Usually, a pressure tank is interposed between the pump outlet and the dispensing line through which the liquid egresses from the system. The motor is operated by a pressure switch so constructed as to turn the pump on when the pressure in the system falls below a prescribed lower limit and to shut the pump off when the pressure in the system rises above a prescribed upper limit. As a result, the pump goes on and off, or recycles, a number of times while the liquid is being drawn from the system and the liquid is drawn from the system at a pressure that varies between the prescribed lower and upper limits. This recycling of the pump causes a strain on the pump motor and frequently causes the pump motor to burn out prematurely.

This invention has the object of doing away, in a system utilizing the above described type of pump, with the recycling of the pump during the drawing of the liquid from the system while enabling the liquid to be dispensed at a uniform pressure. This is accomplished by providing a pressure relief valve and a flow control valve in the system that are interposed between the pump outlet and the pump inlet. The pressure relief valve is set to open at a pressure that is between the prescribed upper and lower limits and the flow control valve is so constructed as to permit the flow of liquid therethrough at a rate that is less than the pumping rate of the pump.

In the drawings:

FIG. 1 is a schematic representation of the system; and

FIG. 2 is a partially sectional view of a manifold in the system.

A pump 10, having an inlet line 12 connected to the pump inlet and an outlet line 14 connected to the pump outlet has a capacity of gallons per minute. The pump is operated by a motor 16 which is controlled by a pressure switch 18. A control line 20 extends from the pump to the pressure switch and the pressure switch is so set that it causes the motor to start the pump when the pressure of the system falls below 30 pounds per square inch and to stop the pump when the pressure of the system rises above 50 pounds per square inch.

The line 12 isconnected to the left portion of a manifold 22 and the line 14 is connected to the right portion of the manifold. Liquid, usually water, entering the manifold 22 through the line 14 can branch leftwardly toward a pressure relief valve 24 (described below) and rightwardly through a line 26 into a pressure or storage tank 28. The pressure switch 18 is connected to the line 26. A dispensing line 30, exiting from the pressure tank 28, is connected to the place where the liquid is to be used wherein a conventional valve is provided to turn the liquid olf and on. A supply line 32, extending from the source of the liquid, is connected to the inlet line 12.

The pressure relief valve 24 comprises an orifice 32 surrounded by a seat 33 that is adapted to be closed by a valve head 34. The head is mounted to a stem 36 that is slidable in a wall 38 and whose end remote from the head 34 is slidable in a screw 40. A compression spring 42 extends between the screw 40 and a ring 44 that is secured to the stem 36 so as to yieldably urge the head 34 against the orifice 32. The screw 40 is threaded into the manifold 22 and may be moved inwardly and out wardly to thereby adjust the pressure with which the spring 42 urges the head 34 against the seat 33. In the illustrative example of the invention, the screw is so set that the valve 24 opens when liquid under a pressure of 45 pounds per square inch flows leftwardly against the valve.

A flow control valve 46 is located in the manifold 22 between the pressure relief valve 24-and the connection between the

lines

12 and 32. The flow control valve 46 is so constructed as to permit, in the illustrative example set forth herein, a flow of up to 9% gallons of liquid per minute.

In the idle position, with no liquid being drained from the tank 28 through the line 30, the pressure in the system is above 50 pounds per square inch and the motor 16 and the pump 10 are shut off. Assuming that one gallon per minute is drained form the tank 28 through the line 30, the pressure in the system will fall below 30 pounds per square inch and the switch 18 will cause the motor 16 to turn the pump on and cause liquid to flow through the line 14 at the rate of 10 gallons per minute and gradually build up the pressure in the system. However, despite the fact that the pump is forcing liquid through the system at a greater rate than is being discharged through the line 30, the pressure in the system will not rise above 50 pounds per square inch and thus cause the switch 18 to stop the pump 10 until the flow of liquid though the line 30 is terminated. This results from the fact that when the pressure in the system reaches 45 pounds per square inch the pressure relief valve 24 opens and the excess liquid, in this case 9 gallons per minute, flows through the valve 24 and the flow control valve 46 back to the pump 10.

Should the liquid flowing through the line 30 be increased, for example, to 2 gallons per minute, then 8 gallons per minute will flow back to the pump through the line 12. Put another way, the pump 10 will keep operating with the surplus liquid flowing back to the pump through the flow control valve 46 when the line 30 is drawing up to 9% gallons per minute.

When the flow of liquid through the line 30 is terminated, one-half gallon of the 10 gallons per minute being pumped will not be able to flow through the flow control valve 46 so that pressure in the system will gradually build up and reach 50 pounds per square inch so as to cause the valve 18 to shut off the motor 16 and the pump 10.

The tank 28, as is conventional, has an air compartment at its top. When the tank is full, the air in the tank is compressed by the water so that the system pressure is relatively high. When the volume of water in the tank 28 is diminished by drawing it off through the line 30, the air in the tank expands and the system pressure is diminished.

Should some of the air leak from the tank 28 so that the tank becomes waterlogged, a greater volume of water enters the tank than would have before the air leakage. With a waterlogged tank, the drawing off of a relatively small volume of water causes the same drop in the system pressure that would be caused by the drawing off of a relatively large volume of water in a tank that is not waterlogged. Thus, in the systems improved on by this invention, a waterlogged tank results in pump being turned on or off or recycled with greater frequency. Therefore this invention, by keeping the pump running continuously as long as water is being drawn through the line 30, is especially advantageous with a water-logged tank.

I claim:

1. A fluid pumping system comprising: a pump, having an inlet and an outlet, so constructed as to be actuable to pump fluid at a first prescribed rate through the outlet; a supply line, extending to a source of fluid, in communication with the inlet; a dispensing line, in communication with the inlet; a dispensing line, in communication with the outlet, through which the fluid may be drawn to a place of use; an actuating mechanism, interposed between the outlet and the dispensing line, so connected to the pump as to cause the pump to start when the pressure between the outlet and the dispensing line is below a prescribed lower limit and to cause the pump to stop when said pressure exceeds a prescribed upper limit; a normally closed pressure relief valve, interposed between the outlet and the inlet, so constructed as to open in response to the application of said pressure at a level between said upper and lower limits; and a flow control valve, interposed between the outlet and the inlet and in communication with the pressure relief valve, so constructed as to permit the flow of the fluid therethrough at a second prescribed rate that is less than said first prescribed rate.

2. The system as defined in claim 1 wherein the flow control valve is interposed between the pressure relief valve and the supply line.

3. The system as defined in claim 1 further comprising a pressure tank interposed between the outlet and the dispensing line.

4. The system as defined in claim 3 wherein the flow control valve is interposed between the pressure relief valve and the supply line.

5. The system as defined in claim 1 further comprising: a manifold having a first portion in communication with the inlet and a second portion in communication with the outlet; and means mounting the pressure relief valve and the flow control valve in the manifold between said first and second portions.

6. The system as defined in claim 5 wherein the flow control valve is so mounted in the manifold as to be interposed between the pressure relief valve and the supply line.

7. The system as defined in claim 5 further comprising a pressure tank interposed between said second manifold portion and the dispensing line.

8. The system as defined in claim 7 wherein the flow control valve is so mounted in the manifold as to be interposed between the pressure relief valve and the supply line.