US2391043A - Poppet changeover for liquefied gas systems - Google Patents

Description

3W 18, 1945. T. A. ST. CLAIR 2,391,043

POPPET GHANGEOVER FOR LIQUEFIED GAS SYSTEMS Filed Dec. 16, 1941 2 Sheets-Sheet 1 mum:

INVENTOR T. A. .ST CLAIR Dec. 18, 1945. T. A. sT. CLAIR POPPET CHANGEOVER FOR LIQUEFIED GAS SYSTEMS Filed Dec. 16, 1941 2 Sheets-Sheet 2 INVENTOR T.A. STCLAIR ,ATTO EY Patented Dec. 18, 1945 UNITED STATE s PATENT OFFICE 1 POPPET CHANGEOVER FOR .LIQUEFIED GAS SYSTEMS Theodore A. St. Clair, Pontiac,

Phillips Petroleum Company, a

- Delaware Micln, assignor to corporation of Application December is, 1941, Serial No. 423,235 7 Claims. (01. 62-1) The present invention relates to a fully automatic changeover valve for use in dispensing systems utilized in the vending of fuel gases for domestic consumption.

Heretofore, domestic equipment for the dispensing of liquefied petroleum gases of the selfservice type, that is, customer operated two-drum systems including supply and reserve containers, have employed some means for efiecting the automatic change in withdrawal connections from the supply source previously utilized to the reserve container. Various fully and semi-automatic de-' vices have been proposed for eifecting the changeover, thereby avoiding temporary cessation of fuel supply. The most satisfactory semi-automatic system employed primary pressure regulators in connection with the respective cylinders provided with manual means for adjusting outlet pressure by limiting diaphragm area and spring pressure. Preferential withdrawal is obtained in the latter case from the cylinder having the highest outlet pressure setting. This system had the disadvantage in addition to requiring special regulators that each regulator had to be initially set on the replacement of an exhausted container. resulting sometimes in confusion on the part of customers unversed in mechanical contrivances.

So far as I am aware, fully automatic changeover devices have uniformly employed a. complicated array of diaphragms and pressure responsive springs which added to manufacturing as well as installation and servicing costs. It is the purpose of the present invention to provide a changeover valve for self-service systems for the utilization of fuel gases which is fully automatic and efllcient without diaphragms and pressure responsive spring devices. The present device, as later more fully described, is fool proof in operation and preferably employs a simple first stage regulator with a fixed outlet setting.- The improved changeover valve is characterized by simplicity of construction and a minimum number of operating parts, the operation for effecting change of withdrawal connections depending upon pressure differential existing across a simple valve. Each sourceof gaseous supply is provided with respect to a selectively operable loading device that changeover will occur when the pressure of the reserve cylinder supersedes the combined force of the loading means and the failing pressure of the supply cylinder. Indicatingmeans are provided so that the customer may A primary object of the present invention is to provide an improved changeover device which is fully automatic and of simplified construction requiring no manipulation of mechanical settings by the operator. Another object is an automatic changeover which is operable by the connection of a'supply cylinder. A further object of the invention is the submission of a fully automatic changeover device which enables utilization of simplified pressure reducing means. A still further object of the invention is to produce a system for the dispensing of fuel "gases which will require sumer.

a minimum amount of attention from the con- Another and very important objectis the development of an automatic changeover valve in which the preferential withdrawal is obtained through the use of mechanical loading means thereby eliminating diaphragms and similarly frangible devices. A further object is the provision of an automatic changeover which will of exhaustion of matic dispensing equipment of the present invention. set up for attachment to liquefied petroleum gas containers and showing one of the first stage regulators in partial vertical section. F gure 5 is a diagram showing the forces involved in the-changeover.

Referring first to Figures 1 and 2, the number I refers generally to the poppet changeover of this invention which includes a cast brass or iron with a valve of the aforementioned type so located body 2 provided with two inlet passages 3 and 4 and one outlet passage 5 having a connection 6 for attachment ,to a second stage regulator shown in outline in Elgure 3 to be later described. A

base 1, integral with the changeover body, is provided for Zmounting the device on a suitable bracket w'hen connected in the dispensing system. )f'alve seat bushings or sleeves 8 and 9, provided with integral valve seats I0 and II of narrowed cross section, are mounted within the inlet massages in the body 2 and pass through openings readily observe when a changeover, from one source of supply to the other source has occurred.

IA and 9A in the rocker support l2 shown moutline in Figure 3. The rocker support has a censs tral openlng J1 registering with the outlet passage 5. The arms I and I5 are provided with apertures in their outer ends to form bearings when bent into supporting position for the rocker shaft It as shown in Figure 1. The shaft l6 extends through the lower portion of a rocker I1, properly weighted to apply the requisite loading to the poppet valves l8 and I9 which slide within the bushings 8 and 9. The bushings are each provided with a number of ports 20 and 2|, respectively. A transparent cap 22 of glass, lucite or other suitable plastic encloses the weighted rocker or semaphore and valve assembly enabling observance of .a changeover and defining a chamber 22A above the valves.

The poppet valves are elongated so as to be selectively loaded against outlet pressure of the reserve cylinder by the rocker when seated thereby obtaining preferential withdrawal from the supply cylinder. The valve faces are preferably of tapering contour so as to expose a relatively limited area through the restricted inlet passage at the valve seat. When th differential across the valve reaches a magnitude suflicient to eflect a changeover and unseat the, valve, the larger area exposed to inlet pressure moves the valve the balance of its travel with sufficient force to move the weighted rocker pastthe center and seat the valve controlling flow from the previously utilized supply cylinder.

Referring to Figure 4, the poppet changeover is shown connected to first stage pressure regulators 23 and 24 by flexible hoses 25 and 26, respectively. Any suitable regulator may be employed, although the regulators are preferably similar to the type shown and described in my application Serial No. 281,967, filed June 29, 1937,

which utilizes a back flow check'valve to prevent gas loss on reversal of flow when an exhausted container is disconnected. This contingency is not paramount with the present invention, however, since reversal of fiow is reduced or entirely eliminated by the changeover valves. A double insurance against leakage on cylinder disconnection results where check valveregulators are employed by virtue of the more positive seal between the regulator diaphragm and the valve seat. The regulator 23 is shown in partial vertical section and includes a diaphragm 21 clamped between the body 28 and dome 29, vented to the atmosphere through an aperture 30. A coil spring 3| is disposed in the dome above the diaphragm and an enlarged diaphragm chamber 32 is provided for the elimination -of buzzing between the push-pin 33 and conduit 34 communicating with the fuel container, not shown. The check valve seat 35 is adapted to' be engaged by the diaphragm when a container is disconnected. The operation of the pressure regulator in connection with the fuel container outlet valve will not be here fully described, since it forms no part of the present invention and is adequately shown and explained in my above-mentioned application. It is noted that the present invention permits a simplified form of regulator which may be built to deliver a constant outlet pressure, thus eliminating the diaphragm adjusting mechanisms shown in my earlier application. The outlet 6 of the changeover mechanism is connected to a second stage pressure regulator 36 of conventional design, which in turn communicates with the service line 31 leading to gas consuming appliances. A clamp or tab 38 serves to identify the cylinder which is on supply when flow is initiated. Cylinders 40 and 4| serve to supply gas under pressure to the changeover mechanism I via regulators 23 and 24, and hoses 25 and 26, respectively.

The operation of the device is readily understood by reference to the attached drawings and foregoing description. Upon connection of a first tank of gas to the arrangement shown in Figure 4, for example to the regulator 23, a differential pressure is created across the valve port and poppet valve on the connected side of the changeover. The identification clamp 38 is then applied to the hose of the reserve container, as shown in Figure 4. Differential pressure causes the valve l3 to rise to the position shown in Figure 1, forcing the rocker ll past center and loading valve I9. Upon connection of the second cylinder to the regulator 24, valve is remains seated by virtue of the applied loading and due to the larger area exposed on the valve l8 to inlet pressure. The rocker, therefore, points to the right, or reserve cylinder, as shown in Figures 1 and 4. Flow will occur from the supply source through the primary regulator 23, hose 25, ports 20, outlet 5 and second stage regulator 36 to the service line 31 in accordance with the demand of the consuming appliances. The primary regulators are preferably constructed to deliver an outlet pressure of approximately 4.5 pounds per square inch at a tank pressure of pounds per square inch to the changeover valve. The second stage regulator is conventionally adjusted for an outlet pressure to the service line of 11 inches of water, i. e., about 0.4 pound per square inch. On the failure of pressure from the supply cylinder, changeover will occur when the effecexceeded by the reserve cylinder pressure on the valve area exposed through the valve seat. When this condition occurs the valve position shown in Figure 1 is reversed tipping the rocker to point in the direction of the empty cylinder.

In Figure 4 regulators 23 and 24 hold the pressure in both passages 3 and 4 of Figure 1 at about 4.5 pounds per square inch; even though the pressure in the full and as yet unused reserve tank attached to 24 may be 100 pounds per square inch, and that in the used tank attached to 23 may be 4.5 pounds per square inch. In Figur 1, hole 20 allows space 22A to also be at 4.5 pounds per square inch. Therefore, as the pressure in the almost exhausted used tank, and in spaces 8 and 22A, falls below 4.5 pounds per square inch the opposing forces are (A) about 4.5 pounds per square inch times the area of valve seat ll acting upwardly on pin I9; and (B) the falling pressure in passage 22A times the area of pin I 9, plus the weight of pin I 9 and the weight of rocker I1 acting downwardly on pin I9. Pin l8 has dropped away due to its weight if the rate of flow through pipe 5 is at all reasonable, but if the flow through 5 were great, it would add to force B the difference of pressure between points 8 and 22A times the area of the pin l3 minus the weight of pin l8; which obviously i a, relatively minor force.

The weight of rocker ll of course acts through its center of gravity about pin l6, which gives it a shorter lever arm than pin l9 has relative to pin I 6 as shown in the illustrative embodiment of the invention in Figure 1. Other proportions could be chosen giving different lever arms.

When force A becomesgreater than force B a quick changeover occurs; because as rocker I1 is tilted the lever arm of the center of gravity about pin I6 is constantly reduced until grav can calculate the proper diameter of to a supply line,

ity becomes an aiding force instead'of a resisting force; and because pin is presents a larger diameter than seat ll forthe same gas pressure as soon as pin I9 leaves pin 19, seat H, and the proper size and weight of rocker H to give a quick changeover when the pressure in the exhausted cylinder falls any desired substantial amount below 4.5 pounds per square inch, and the pressure can fall to 0.4 pound per square inch before the user would notice any change. This is due to second stage regulator 36 which is set at 0.4' pound per square inch delivery pressure through pipe 31.

The formula to use is obvious from Figure 5. The sum of the torques about any point being equal to the moment of inertia times the annular acceleration (in this case the annular accel eration is zero). In these formulas W=weight of rocker, w=weight of pin, P=4.5 pounds per square inch, p=desired lesser pressure, j=failing pressure in the used tank, A=area of pin, a=area of orifice H, e is the pivot point, the center of gravity of the rocker, and b, d and h the distances indicated in Figure 5.

2Te=0 -Wd+ (PapAw)b((f-p)A-w)h=0 Wd-Pab+wb+fAh-t o h AXE- 5 In most cases the flow through passages 8, 22A and 5 will be always slow enough so that w can be made greater than (f-p)A and then pin i8 falls away and the formula becomes:

It is understood that other loading means may be employed for the valves in lieu of the weighted rocker.

It is thus apparent that by the present invention I provide a fully automatic device which is characterized by simplicity, durability, and ease of operation by the consumer.

I claim:

l. A system for the storage and utilization of liquefied gascomprising two sources of gas under pressure, a conduit leading from each source to a supply line, a valve controllin the flow of gas in each conduit, each of said valves having a vertically moving element which rises under fluid pressure in its respective conduit as the valve opens and lowers as the valve closes, and a weighted rocker movable into loading engagement with oneof sad elements by the movement of the other of said elements in response to the pressure in the conduit controlled by said other element as the pressure in the conduit controlled by said one element falls to a low value.

2. A system for the storage and utilization of liquefied gas comprising two sources of gas under pressure, a conduit leading from each source a valve controlling the flow of gas in each conduit, each of said valves having a movable element which moves under fiuid pressure in its respective conduit as the valve opens, and loading means movable into loading engagement with one of said elements by movement of the other of. said elements under the pressure the seat. Any engineer in the conduit of said other element as the pressure in the conduit controlled by said one element falls to a low value.

3. A system for the storage and utilization of liquefied gas comprising a sealed valve housing having two gas inlet ports opening into said housing through passages, means for connecting two sources of gas under pressure to said inlets, said housing having an outlet for connection with gas consuming app 'ances, the inlet ports in said housing being shaped to form valve seats. valve members in said passages for engaging said seats against the pressure of said sources respectively, and a loading member in said housing alternately movable by each or said valve members to urge the other of said valve members in a seating direction, the arrangement being such that when the pressure of the gas source associated with one of said valve members falls substantially below the pressure of the other source said loading member is urged into engagement with said one valve member by the movement of the other of said valve members under the pressure of said other source and the pressure of said other source aids said loading memher in holding said one valve member in seated position.

4. In the combination of claim 3, said loadin member being pivotally mounted in said housing on a pivot point below its center of gravity.

5. In the combination, of claim 3, said housing being transparent so that the position of said loading member indicates which source is sup p y as to the service line.

6. -A system for the storage and utilization of liquefiedgas comprising two sources of gas under pressure, a sealed housing, a portion at least, of

which is transparent, a conduit leading from.

each source of gasunder pressure to an opening into said housing, a supply connection from and open to the interior of said housing, a valve controlling the fiow of gas in each conduit, each avertically moving elethe position of said loading means being visible.

'7. A device for utilization of liquefied gas from two sourcescomprising'a sealed valve housin having two gas housing through passages, means for connecting two sources of gas under pressure to said inlets, said housing having an outlet for connection with gas consuming appliances, the inlet ports in said housing being shaped to iorm valve seats, valve members in'said passages for engaging said seats against the pressure of said sources respectively, and the loading member in said housing alternately movable by each of said valve members to urge the other of said valve members in a seating direction, the arrange-' ment being such that when the pressure of the gas source associated with one or said valve members falls substantially below the pressure or the other source said loading member is urged into engagement with said one'valve member by the movement of the other or said valve members under the pressure of said other source, and the pressure or said other source aids said loadin member in holding said one valve member in seated position.

THEODORE A. ST. CLAIR.

inlet ports opening into said 1

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