US3733449A

US3733449A - Pump protection system with pressure responsive switch and float valve

Info

Publication number: US3733449A
Application number: US00182727A
Authority: US
Inventors: L Parker
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-09-22
Filing date: 1971-09-22
Publication date: 1973-05-15
Anticipated expiration: 1990-05-15

Abstract

A safety cutoff device mounted on a pressure tank between the tank and the pressure activated pump switch for automatically locking the switch open upon the reduction of air in the tank to the point at which damage could result to the pump electrical system should the pump be allowed to continue to operate. The safety cutoff includes a float valve which is activated to segregate a pressure accommodating auxiliary tank in direct communication with the switch from the pressure tank upon the reduction of air and elevation of water level in the pressure tank to a predetermined point. The air, under pressure, locked within the auxiliary tank in turn locks the switch open and in effect deactivates the entire system until reset.

Description

HD1196 States Patent 91 Parker 51 May 15, 1973 Laurence J. Parker, Guthrie, Okla.

George C. Chiga, Guthric, Okla. a part interest Sept. 22, 1971 Inventor:

Assignee:

U.S. Cl. ..200/81 R, 137/209, 200/83 Q, 417/44 Int. Cl. ..H0lh 35/24 Field of Search ..200/84 B, 83 Q, 81 R, 200/83 R; 137/399, 405, 456, 209; 417/9,

References Cited UNITED STATES PATENTS 3,478,688 11/1969 Lind ..4l7/44 X 2,692,558 10/1954 Garrett ..417/44 3,393,641 7/1968 Miedaner et a1. 1 37/209 Primary Examiner-Robert K. Schaefer Assistant ExaminerRobert A. Vanderhye AttorneyClarence A. OBrien [57] ABSTRACT A safety cutoff device mounted on a pressure tank between the tank and the pressure activated pump switch for automatically locking the switch open upon the reduction of air in the tank to the point at which damage could result to the pump electrical system should the pump be allowed to continue to operate. The safety cutoff includes a float valve which is activated to segregate a pressure accommodating auxiliary tank in direct communication with the switch from the pressure tank upon the reduction of air and elevation of water level in the pressure tank to a predetermined point. The air, under pressure, locked within the auxiliary tank in turn locks the switch open and in effect deactivates the entire system until reset.

6 Claims, 4 Drawing Figures PAIEMED HAY] 5197a SHEET 1 [1F 2 Fig.

Fig. 4 T

PA HA IENTED "51975 v 3.733.449

SHEET 2 UP 2 Fig.2

PUMP PROTECTION SYSTEM WITH PRESSURE RESPONSIVE SWITCH AND FLOAT VALVE The present invention is generally concerned with automatic domestic water systems utilizing hydropneumatic accumulators or pressure tanks, and more particularly relates to a safety device for such systems to prevent excess cycling and damage to the electrical system of the pump.

A pressure tank of the type with which we are herein concerned generally operates in accordance with Boyles law concerning the inverse varying between volume and pressure. In other words, when water is pumped into a pressure tank against a cushion of compressed air, the pressure rises as the air space is reduced. As the air space is reduced, the space containing water increases. It thus follows that within a pressure tank of known volume. a difference in pressure represents a specific quantity of water.

In an automatic water system, the pressure levels are controlled by a pressure activated switch which will turn the pump on at one pressure level and turn it off at another. The quantity of water that can be drawn from the pressure tank between these pressure levels determines the frequency of starts imposed on the pumps electrical system. Because of the heat generated in starting such an electrical system, the life of such a system can be substantially diminished if excessive starts are required. Thus, the greater amount of water which can be drawn between the starts, the greater will be the life expectancy of the pumps electrical system. When the time interval between starts becomes so short as to not provide sufficient time for the heat in the electrical components to dissipate, the situation becomes critical and is known as short-cycling.

The short-cycling problem will arise as the quantity of water available between pressure levels diminishes due to a decrease in the pneumatic cushion. The maintenance of such a cushion is extremely difficult due to air exiting entrained in the water, leakage around pipe fittings, as well as possibly through the porosity of the material of the tank itself, etc.

The aforedescribed air leakage is, for all practical purposes, almost impossible to prevent. Accordingly, it is the primary object of the instant invention to provide a safety cutoff device which automatically locks the pump switch open and deactivates the system upon the air cushion diminishing to the extent that the quantity of water that can be drawn from the tank before the pump starts is inadequate and continued operation could have a detrimental effect on the system. The safety device, while highly unique, is of a relatively simple and trouble-free construction, operating automatically and efficiently so as to lock a pocket of pressurized air within an auxiliary tank in direct communication with the pressure responsive pump switch for maintaining the switch open until the system can be properly reactivated.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIG. 1 is an elevational view of a pressure tank with the safety device of the instant invention mounted thereon;

FIG. 2 is an enlarged cross-sectional view through the tank communicated safety device;

FIG. 3 is a cross-sectional view taken substantially on the plane passing along line 3-3 of FIG. 2; and

FIG. 4 is an elevational view of the cutoff valve in its closed or system-sealing position.

For purposes of illustration, the pressure-tank 10 in FIG. 1 represents a standard 42 gallon tank with a 16- inch diameter and a 50-inch altitude. It is the practice of those skilled in the trade to pump compressed air into such a tank to a gauge pressure of about 5 psi less than the cut in pressure level of the pressure activated switch 12. Water is then pumped into the tank 10 until the pressure has risen to the cut out level of the switch 12. In the illustrated tank, the initial charge of compressed air will be l5 psi with the cut in pressure level of the switch 12 being 20 psi, represented by level indicating line 14. The cut out pressure level will be 40 psi represented by level indicating line 16. The amount of water which can be drawn from the tank between the levels 14 and 16 is approximately 13.1 gallons. However, as the tank 10 loses its initial charge of compressed air, the water level changes as well as the performance of the system. For example, when the initial air charge is gone, the water levels between the 20 psi cut in and the 40 psi cut out will occur much higher in the tank, between the cut in level 18 and the cut out level 20. Further, the amount of water between the new cut in and cut out levels 18 and 20 is substantially reduced, being on the order of 6.5 gallons. This amount of water offers only marginal protection for the electrical components of many domestic water systems and, depending on the volume of water, its pressure, and the manner in which it moves through the system, the continued loss of air could result in an acute short-cycling which will damage and possibly destroy the pumps electrical components. It is the purpose of the invention herein to provide a safety device 22 which will lock the pump pressure switch 12 open and terminate operation of the system when the area of marginal protection is reached.

The safety device 22 mounts on the side of the tank 10 and is in water-flow receiving communication therewith through a nipple 24 engaged with the tank at out out level 20.

The safety cut out device 22 includes a control valve unit 28 with which the nipple 24 communicates. The nipple 24 defines the inlet to the valve unit 28 and communicates therewith above a downwardly directed valve seat 30 against which a floatable ball valve 32 selectively engages. The valve seat 30 is located at the upper end of a cylindrical chamber 34 which vertically guides the ball 32 for proper seating thereagainst. The lower portion of the chamber 34 is in turn communicated with a second upright chamber 36 which includes an upper end outlet 38, also located above the valve seat 30 and generally at a heighth corresponding to the heighth of the nipple 24. The outlet 38 communicates the chamber 36 directly with the enlarged auxiliary tank 26.

The pressure switch 12 is mounted directly over the auxiliary tank 26 and communicated therewith through an aperture 40 and mounting nipple 42 whereby the pressure in the auxiliary tank can be directly communicated thereto. An appropriate pressure gauge 44 is also mounted on and communicated with the interior of the tank 26. I

In normal operating conditions of the system, the water level within the pressure tank is below level 20, and as such, the safety cutoff device is inoperative with the ball float 32 dropped downward away from the valve seat 30 and the compressed air pressure within the tank 10 in free flowing communication through the safety device 22 for a controlled operation of the pressure switch 12. However should over a period of time a substantial loss of air within the tank 10 occur, the water levels therein will eventually rise to the danger levels indicated by lines 18 and 20. At such time as the cutoff level reaches a height within the pressure tank sufficient so as to allow for a flow of water through the nipple 24 into the safety cutoff device 22, the pressure within the auxiliary tank 26 will be sufficient so as to cut off the pressure switch 12. At the same time, water from the pressure tank 10 will flow into the control valve unit 24, float the ball valve 32 upward into sealing seated engagement against the valve seat 30, and lock the pressure switch in its open or cutoff position. Further, the pressure within the auxiliary tank 26, which directly controls the pressure switch 12, will be locked in or maintained by the water seated ball 32, this being illustrated in FIG. 4, and as such, any continuing decrease in the air pressure within the pressure tank 10 will not reactivate the pressure switch 12. Thus, the entire system is rendered inactive so as to prevent possible damage to the pump or electrical components thereof.

Once the system has been deactivated, a series of steps are necessary to reactivate the system. These steps include first a turning off of the current to the pressure switch, and then draining the water from the control valve 28, auxiliary tank 26 and pressure tank 10. Appropriatedrain cocks 46 can be provided as required. Once the water has been drained, air is pumped into the tanks through an appropriate air valve 48 communicating with the control valves immediately above the nipple 24. Air is pumped into the system until the desired precharge of compressed air has been established, the pressure gauge 44 enabling an easy determination thereof. The system is then ready to commence operation and the current to the pressure switch is turned on.

While several steps are required to reactivate the system and may thus be considered an inconvenience to.

the home owner, the avoidance of damage to the pump and/or electrical system is considered to more than offset such inconvenience. Further, in any system incorporating a well constructed pressure tank, loss of air will be at a minimum and the safety cut out device only operative on very rare occasions.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

What is claimed as new is as follows:

1. In a pressurized water system, a pressure tank, a pump controlling pressure switch, a cut out device interposed between the pressure tank and the pressure switch and providing selective free communication therebetween, and cutoff means within said cutoff device for termination of communication between the pressure tank and pressure switch and selectively locking a predetermined pressure within said cutoff device in pressure switch controlling communication with the pressure switch, said cutoff means including an upper portion directly communicated with said pressure tank for the selective reception of water therefrom upon the rising of the water in the pressure tank to a preselected height, said cutoff means comprising buoyant float valve means, and a valve seat positioned vertically above the float valve means and between the float valve means and the point of communication with the pressure tank whereby upon the introduction of a selected amount of water from the pressure tank into the cutoff means, the buoyant float valve means will rise and seat against said valve seat, thereby effecting said termination of communication between the pressure tank and pressure switch.

2. In a pressurized water system, a pressure tank, a pump controlling pressure switch, a cut out device interposed between the pressure tank and the pressure switch and providing selective free communication therebetween, and cutoff means within said cutoff device for termination of communication between the pressure tank and pressure switch and selectively locking a predetermined pressure within said cutoff device in pressure switch controlling communication with the pressure switch, said cutoff means being responsive to the water level within the pressure tank, said cutoff means comprising a buoyant ballvalve and a valve seat positioned vertically thereabove for selective engagement by the ball valve upon the introduction of a sufficient level of water into the cutoff means.

3. The system of claim 2 wherein said cutoff device includes an auxiliary tank between the cutoff means and the pressure switch, said predetermined pressure being locked within said auxiliary tank.

4. The system of claim 3 wherein said valve seat is located vertically below the points of communication between the cutoff means and the pressure tank and the cutoff means and the .auxiliary tank.

5. The system of claim 3 wherein said cutoff means includes a vertical chamber containing said ball valve and acting as a vertical guide therefor, the upper end of said chamber communicating directly with the pressure tank, said valve seat being positioned at the upper portion of the chamber vertically below the point of communication with the pressure tank, the lower portion of the chamber communicating directly with the lower portion of a second adjacent vertical chamber, the upper portion of the second chamber, at a height above the valve seat, communicating directly with said auxiliary tank.

6. The system of claim 5 including water draining means within the cutoff device for a selective withdrawal of water therefrom and a resultant disengagement of the ball valve from the valve seat.

Claims

2. In a pressurized water system, a pressure tank, a pump controlling pressure switch, a cut out device interposed between the pressure tank and the pressure switch and providing selective free communication therebetween, and cutoff means within said cutoff device for termination of communication between the pressure tank and pressure switch and selectively locking a predetermined pressure within said cutoff device in pressure switch controlling communication with the pressure switch, said cutoff means being responsive to the water level within the pressure tank, said cutoff means comprising a buoyant ball valve and a valve seat positioned vertically thereabove for selective engagement by the ball valve upon the introduction of a sufficient level of water into the cutoff means.

4. The system of claim 3 wherein said valve seat is located vertically below the points of communication between the cutoff means and the pressure tank and the cutoff means and the auxiliary tank.