US3434634A - Liquid dispensing apparatus - Google Patents

Description

March 25, `1969 LIQUID DISPENSING APPARATUS Filed Jan. 25. 1967 sheet of s ATTORNEY R. K. GELLATLY 3,434,634 i March 25, 1969 R. K. GELLATLY 3,434,634

LIQUID DISPENSING APPARATUS Filed Jan. 25, 1957 sheet Z of s izo' :25

no `FWIIS E He .438 152` @Se se 'zo 25 A90 a@ a 114 '83 1223d v xof |76 Y@ 12B INVENTOR ROBERT K. GELLATLY ATTORNEY March 25, 1969 R. K. GELLATLY 3,434,634

LIQUID DISPENS ING APPARATUS Filed Jan. 25, 1967 sheet 3 of 3 me i= @J me S I 'I E E H2 88 l 8O Y 202 g 20A 20a f/-d HO INVENTOR. ROBERT K. GELLATLY ATTORNEY United States Patent Ofiice 3,434,634 LIQUID DISPENSING APPARATUS Robert K. Gellatly, Santa Clara, Calif., assignor to FMC Corporation, San Jose, Calif., a corporation of Delaware Filed Jan. 25, 1967, Ser. No. 611,629 Int. Cl. G01f 1.1/32; B65b 37/00 U.S. Cl. 222-450 6 Claims ABSTRACT F THE DISCLOSURE Cross reference to related applications T he subject liquid dispensing apparatus is designed for use in a carton forming and filling machine of the type disclosed in the pending application of Vadas et al., Ser. No. 461,73 8, and is an improvement of the dispensing apparatus disclosed in the pending application of Gellatly, Ser. No. 514,181 which issued on Aug. l5, 1967 as Patent No. 3,335,921, said applications both being assigned to the assignee of the present invention.

Background of the invention This invention pertains to liquid dispensing apparatus and more particularly relates to a positive displacement filling apparatus having an improved foot valve for rapidly filling a predetermined quantity of liquid such as milk, into a container.

When filling cartons in excess of the rate of about 125 quart cartons per minute with the type of filler disclosed in the above mentioned Vadas et al. application, it has been noted that the milk tends to foam because of the high velocity and turbulence imparted to the milk by the restriction caused by the foot valve in the valve body or filling tube. Experimental data also appears to indicate that the rapid opening of the foot valve causes the milk to -ow out of the filling tube past the foot valve in the form of a large diameter tubular, as distinguished from a cylindrical, stream of liquid, and that an air bubble is trapped within the tubular stream thereby increasing the tendency of the milk to foam.

Summary of the invention The dispensing apparatus of the present invention is designed to overcome the foaming problem by providing a double-opening foot valve which initially opens a relatively small diameter central port in a sealing ring of the foot valve thereby causing the initial flow of milk to be in substantially the form of a small diameter cylindrical stream through the central port thus preventing the formation of a bubble therebelow. Thereafter the ring is lifted from its seat in the filling tube to completely open the foot valve permitting a high volume, slow speed fiow of milk from the filling tube past the outside surfaces of 3,434,634 Patented Mar. 25, 1969 the ring as well as through the central port in the ring thereby greatly reducing the velocity and turbulence at the foot valve, and accordingly, reducing the foaming tendency to a minimum.

Brief description of the drawings FIGURE 1 is a vertical central section of a turret upon which a plurality of dispensing apparatus-es of the present invention are mounted, only two dispensing apparatuses being illustrated therein.

FIGURE 2 is an enlarged side elevation of one dispensing apparatus shown in its retracted position with the foot valve closed, a major portion of the apparatus being cut away to illustrate certain operative components in central vertical section.

FIGURE 3 is an enlarged vertical section of the foot valve taken substantially along lines 3*.-3 of FIGURE 5 illustrating the valve in partially open position.

FIGURE 4 is a section similar to FIGURE 3 but illustrating the foot valve in a fully open position.

FIGURE 5 is an enlarged horizontal section taken along lines 5-5 of FIGURE 4 and illustrating the structure for centering the foot valve within the filling tube.

FIGURE 6 is an enlarged central section illustrating the variable orifice valve in solid lines in a position wherein the foot valve is closed and in a phantom lined position wherein the foot valve is fully open.

FIGURE 7 is an enlarged central section similar to FIGURE `6 but illustrating a modified form of the invention in two operative positions.

Description of preferred embodiment In general, each of a plurality of liquid dispensing apparatus 10 (only two being shown in FIGURE 1) of the present invention is bolted to an outlet opening 12 of a liquid supply tank 14 which is supported upon the upper end of a turret 15. The turret 15 comprises a stationary vertical column 16 which rotatably supports the tank 14 and a stabilizing wheel 17 near its upper end, and which rotatably supports a sprocket 18 and a lower stabilizing wheel 19 near its lower end. A continuously driven conveyor 20 is provided with evenly spaced carriers 21 thereon. Each carrier is adapted to support a carton C in alignment with an associated dispensing apparatus 10 as the carton and the dispensing apparatus 10 is moved around the axis of the column 16, which axis defines the axis of rotation of the turret 15. The sprocket 18 is connected in driving engagement to the lower stabilizing wheel 19 by a drive post 22, and the lower stabilizing wheel 19 is connected to the upper stabilizing wheel 17 and to the tank 14 by a plurality of evenly spaced vertically extending inner guide rods 23 and a plurality of evenly -spaced vertically extending outer guide rods 24.

As clearly shown on the right side of FIGURE 1, each dispensing apparatus is provided with two cam actuated arms 25 and 26 which are guided for vertical movement during the filling operation by one of the rods 23 and by one of the rods 24. An upper nonrotatable cam 27 is rigidly secured to the stationary column 16 and cooperates with the upper arm 25 to vertically reciprocate a first portion of each dispensing apparatus 10, and a. lower non-rotatable cam 28 is silmilarly secured to the stationary column 16 and cooperates with the arm 26 to vertically reciprocate another portion of the dispensing apparatus 10. A large diameter foot valve latching cam ring 29 is mounted in fixed position around the turret 15 outside the path of movement of each dispensing apparatus -by one or more brackets 30 and by a utility post 31, whcih brackets and post are rigidly secured to the frame of the machine. The cam ring 29 is not a truly circular member but includes a small diameter arcuate portion 29a which holds a foot valve of the apparatus 10 closed, and a large diameter portion 29h which permits opening of the foot valve during the filling operation.

It is to ybe understood that the specific details of the turret form no part of the present invention. If a more detailed description of the turret and its actuating mechanism is desired reference may be had to the aforementioned Vadas et al. application. It is also to be understood that the dispensing apparatus 10 need not be limited to turret mounted operation as above described, but the apparatus 10 may be mounted in fixed position and may cooperate with a conveyor which intermittently advances cartons into and out of filling position.

Each liquid dispensingr apparatus 10 (FIG. 2) cornprises an upper tubular housing 66 having a flanged upper end 68 boltoed to and communicating with the tank 14 through one of the openings 12. A generally tubular inlet valve housing 70 has its upper end 70a disposed around the lower end of the housing 66 and sealed thereto by a fiexible sleeve 74 which permits vertical movement of the inlet valve housing 70 relative to the upper housing 66. The lower reduced diameter end 70b of the inlet valve housing 70 is provided with an inlet valve 76 which is alternately moved between an open and a closed position by a cam operated actuated device 78. The upper end portion 80a of a generally tubular liquid measuring housing 80 is slidably received around the lower end portion 70b of the inlet valve housing 70 for vertical movement relative thereto and is sealed thereto by an O-ring 81 and a flexible sleeve 82.

The O-ring 81, sleeve 82 and the adjacent wall of the end portions 80a and 70b define a vacuum chamber 83 which has a check valve 83a communicating therewith that prevents air from entering the vacuum chamber but permits air to be forced therefrom. When the measuring housing 80 moves downward the sleeve displaces substantially all the air from the vacuum chamber 83 through the check valve 83a. During movement of the inlet housing 70 and liquid measuring housing 80 in directions which cause the measuring chamber 88 to diminish in size, the check valve 83a prevents air from entering the vacuum chamber thus creating a vacuum therein as the vacuum chamber enlarges. The vacuum causes the flexible sleeve 82 to fold and cling to the outer wall of the end portion 70b during the carton filling stroke thereby preventing any volume disturbing accordian folds from occurring in the flexible sleeve 82 which would vary the quantity of liquid discharged -from the apparatus 10 during each filling stroke of the liquid dispensing apparatus.

The liquid measuring housing 80 includes a reduced diameter filling tube 84 at its lower end, which filling tube is inserted into a carton C to be filled and has the im- -proved double-opening foot valve 86 of the present invention at its lower end. The liquid measuring housing 80 defines a variable capacity, volumetric liquid measuring chamber 88 which is at all times filled with liquid. A valve actuating device 90 is operatively connected to the foot valve 86 and responds to an increase of pressure within the measuring chamber 88 to open the foot valve 86, the pressure increased in the chamber 88 caused by decreasing the size of the chamber 88 upon movement of the inlet valve housing 70 and the liquid measuring housing 80 toward each other after the inlet valve 76 has first been closed.

The improved foot valve 86 (FIGS. 2 to 5) is of the inwardly opening type and is disposed within the filling tube 84 for movement by the actuating device 90 between the closed position illustrated in FIGURE 2, the partially 4 open position illustrated in FIGURE 3, and the fully open position illustrated in FIGURE 4.

The foot valve 86 comprises a vertically elongated rod having its upper end pivotally connected to a lever 112 of the actuating device 90. A relatively small diameter frusto-conical valve plug 114 is rigidly secured to the lower end of the rod and has a narrow stop lug 116 projecting upwardly therefrom. The foot valve also includes a valve cage 118 having a generally tubular body 120 with a resilient sealing ring 122 rigidly secured to its lower end. When the foot valve 86 is closed, the ring 122 rests on and seals against an inturned lip 123 of the filling tube 84, and the plug 114 rests on and seals a central port 124 in the ring 122.

The body 120 is provided with several elongated vertical slots 125 in its periphery, which slots permit the legs of a rod centering spider 126 to pass therethrough. The centering spider 126 cooperates with an upper spider 128 and both spiders are rigidly secured to the rod 110 and slidably engage the inner cylindrical surface of the filling tube 84 to maintain the rod 110 centered at all times.

As indicated in FIGURE 3, the stop lug 116 projects through one of three lower slots 130 in the body 120 and engages a horizontal edge 132 of said one slot 130 after the rod 110 has been moved upwardly a sufficient distance to space the plug 114 from the central port 124 in the ring 122 thereby partially opening the foot valve. Further upward movement of the rod 110 causes the entire cage 118 to move upwardly thereby completely opening the foot valve 86 as indicated in FIGURE 4. During this movement of the cage 118, the cage is maintained centered by three equally spaced legs 136 formed on a lower spider 138, and similar legs formed on an upper spider 140, both spiders being integrally formed on the cage 118.

In order to prevent chattering of the foot valve during filling, a variable orifice valve 144 (FIG. 2) is provided in the inlet end of the filling tube 84, which valve 144 cooperates with the foot valve 86. The variable orifice valve 144 and foot valve 86 cooperate to eliminate chattering of the foot valve during both a relatively slow preliminary filling operation and a nal rapid filling operation by assuring that sufficient back pressure is retained in the measuring chamber 88 against the valve actuating device 90 during both preliminary and final filling, and by assuring that the flow passages within the dispensing housing are sufficiently open during both preliminary and final lling to accommodate the rate of liquid flow therethrough without a loss of accuracy as to the quantity of liquid being discharged into the cartons.

The variable orifice valve 144 comprises an orifice plate 146 (FIG. 2) which includes an annular flange 148 formed integrally with an annular dish 150 that is inclined downwardly toward a central circular orifice 152. The orifice plate 146 is loosely fitted into the upper end of the filling tube 84 and has the upper end of the foot valve actuating rod 110 of the foot valve 86 extending therethrough.

A cylindrical valve head of substantial length is secured to the rod 110 and is disposed in partially closed or an orifice restricting position in the orifice 152 when the foot valve 86 is in both the closed and partially open positions. It has been found that a radial clearance of between 15-30 thousandths of an inch is necessary between the walls of the orifice 152 and the periphery of the valve head 160 to assure that a sufficient build up of pressure in the portion of the measuring chamber 88 above the Orifice valve 144, will occur, even at slow filling speeds, to fully open the foot valve, and yet will permit a limited amount of the liquid to flow past the orifice valve 144 permitting this limited amount of liqud to How out of the foot valve 86 initially through the port 124 in the ring and thereafter through the port as well as around the outer periphery of the ring. It will be noted that the thickness of the valve head 160 is sufficient to remain within the orifice 152 when the valve is closed and will remain in the orifice until after the foot valve is completely opened as indicated in FIGURE 4.

As indicated previously, the movement of the inlet valves 7'6 is controlled by the actuating device 78 which includes a movable lever 172 that is pivotally supported by the inlet valve housing 70 at 174 and is sealed to the hous` ing by a flexible diaphragm 176. One end of the lever 172 is pivotally connected to a vertically extending actuating rod 178 of the inlet valve 76. A cam follower 180 is journalled on another portion of the lever 172 and rides along a lower camming surface 182 of the cam 27. The inlet valve 76 is normally held in a closed position by a spring 184 connected between the lever 172 and the inlet valve housing 70 and is opened in response to the cam follower 180 riding along a raised arcuate lobe 183 on the camming surface 182.

Since the construction of the foot valve actuating device 90 is substantially the same as that of the inlet valve actuating device 78, the device 90 will not be described in detail. It will be noted now, however, that the lever 112 is pivoted to the measuring housing 80 at 186 and that the foot valve 86 is positively held closed by the small diameter portion 29a (FIG. 1) of the cam ring 29 during a portion of a cycle of operation of the turret and is opened by a build up of pressure within the measuring chamber 88 as the device 80 moves through the arcuate range of the large diameter portion of the ring 2,9.

The inlet housing 70 is vertically reciprocated by an upper flange 188 of the cam 27, which flange engages a cam follower 190 journalled on the upper arm 25. The measuring housing 80 is vertically reciprocated relative to the inlet housing 70 and relative to the carton C to be lilled by a flange 192 on the cam 28 which engages a cam follower 194 journalled on the arm 26.

At the beginning of the cycle of operation of the liquid dispensing apparatus of the present invention, the components of the apparatus are positioned as shown in FIGURE 2 with a carton C to be filled being supported by a carrier 21 directly below the associated filling tube 84. As illustrated in FIGURE 2, the inlet valve 76 is held open by the cam follower 180 of the valve actuating device 78 `which engages an actuating lobe 183 on the annular cam 27, which cam is concentric with the vertical axis of rotation of the turret-supported liquid supply tank 14. At this time, the cam follower 190` that is journalled on the arm 25 holds the inlet valve housing 70 in its uppermost position by riding along the upper iiange 188 of the cam 27. The cam follower 194 on the end of the arm 26 rides along the ange 192` of the annular cam 28, which cam includes adjustable portions (not shown) that may be vertically adjusted so as to control the vertical travel of the measuring housing. Thus, -when it is desired to fill different size cartons with predetermined quantities of liquid, both the adjustable portion of the cam 28 and the vertically adjustable carton carrier 21 are raised or lowered to the desired vertical positions by means fully disclosed in the Vadas et al. application.

In order to positively hold the foot valve 86 closed dur ing the period when the inlet valve 7-6 is opened, latching means such as the annular cam ring 29 is positioned outwardly of the apparatus 10 and engages a portion of the valve actuating device 90 to positively hold the foot valve closed at all times when the inlet valve 76 is open. When the inlet valve is closed, the actuating device 90 enters the portion 29b of the ring 29 permitting the valve 86 to open. The portion 29b also serves to limit the maximum amount of opening permitted the foot Valve 86. It will also be understood that when the inlet valve 76 is closed, atmospheric pressure acting on the external surfaces of the actuating device 90 will be greater than the negative pressure within the measuring chamber 88 and will hold the foot valve 86 closed until the housings 70 and 80 are moved toward each other to provide a positive pressure Within the measuring chamber 88 that is greater than the pressure outside the chamber. In this regard the O-ring 81 and check valve 83a prevent atmospheric pressure from acting on the sleeve 82, and accordingly, a negative pressure Iwill be present within the vacuum chamber 83 and measuring chamber 88 upon any movement which tends to enlarge the measuring chamber 88. It will be understood that the cam track 29 is sufiiciently tall to maintain a position in horizontal alignment with the actuating device 90.

Upon rotation of the liquid supply tank 14 and liquid dispensing apparatus 10 about the cams 27 and 28, the measuring housing 80 is first lowered to draw liquid through the open inlet valve 76 into the measuring chamber 88 of the liquid measuring housing 80, and to move the filling tube 84 into the carton with its lower end disposed immediately adjacent, i.e., about lV16 to 3/8 of an inch, from the bottom closure of the carton. The inlet valve 76 is then closed in response to the cam follower 180 moving off the lobe 183 of the cam 27. With the inlet valve closed and the actuating mechanism 90 released, continued rotation of the dispensing apparatus 10v about the vertical turret axis causes the inlet valve housing to gradually lower, thereby increasing the pressure in the measuring chamber 88 and causing the foot valve 86 to first partially open as indicated in FIGURE 3 and immediately thereafter to fully open as indicated in FIGURE 4, permitting liquid to relatively slowly enter the carton during a prefilling operation to a depth slightly above that of the lower end of the iilling tube. The annular cam 28 then rapidly raises the measuring housing 80 while the housing 70 is held 4from vertical movement, thereby rapidly reducing the volume of the measuring chamber 88 and causing the liquid therein to rapidly flow through the filling tube into the carton.

After the carton has been filled with the desired quantity of liquid and the lower end of the filling tube 84 is within the liquid in the carton, relative motion between the inlet housing 70 .and the measuring housing 80 ceases, thus again establishing the aforementioned negative pressure within the measuring chamber causing the foot valve 86 to close. After the 4foot valve has closed, the cams 27 and 28 raise the inlet housing 70 and measuring housing 80 as a unit thereby withdrawing the filling tube from the carton. Shortly after the foot valve has been closed by negative pressure within the measuring chamber 88, the actuating device 90 enters the small diameter arcuate portion 29a of the latching ring 29 thereby latching the foot valve 86 closed until the cycle of operation is completed.

As mentioned previously, the rapid opening of the foot valve tends to draw a bubble of air within the stream of liquid being discharged lfrom the filling tube. However, in accordance with the present invention, the double opening valve eliminates this problem by first lifting the plug 114 away from the central port 124 in the ring 122 thereby causing the initial stream of liquid Abeing discharged from the filling tube to be in the form of a cylindrical stream of liquid, as opposed to a tubular stream of liquid, thus preventing the entrapment of any measurable amount of a1r within lboundaries defined by the owing liquid. The variable orifice valve 144 (FIGS. 2 -and 6) is arranged to effect the full opening of the foot valve immediately after the initial raising of the plug 114 even during the slow filling rates and pressures which occur during the prefilling operation.

After the liquid discharged into the carton has risen to a height slightly above the lower end of the filling tube 84, the pressure within the chamber 88 is increased due to the rapid upward movement of the measuring housing 80, causing the orifice valve head to raise above the orice 152 permitting a large volume of liquid to flow pastv the orifice plate 146 while maintaining sufficient pressure on the valve actuating device 90 to hold the foot valve completely open and to prevent chattering of the same. With the foot valve 86 completely opened as indicated in FIGURE 4, the remaining portion of the carton can be very rapidly filled without danger of foaming or excess turbulence occurring at the discharge end of the filling tube since the flow passages externally of the ring 122 and through the central port 124 of the foot valve are sufiiciently large to minimize turbulence.

It will be appreciated that the varia-ble orifice valve 1 44 cooperates with the foot valve 86 to control the openlng of the foot valve so that the initial ow of fluid out of the foot valve will be through the central port 124 and so that the foot valve will move to the fully open position immediately thereafter even if the pressure within the measuring chamber 88 is low as is the case when the size of the chamber 88- is slowly reduced during the prefill operation.

As mentioned above, the variable orifice valve 144 includes a cylindrical valve head 160 which is sufficiently long to remain within the orifice 152 until after both the plug 114 and ring 122 have been moved to positions which fully open the foot valve 86. Thus, in the preferred embodiment of the invention the ring 122 moves away from the lip 123 immediately after the plug 114 has moved `away from the ring 122 to fully open the valve even in response to a low pressure within the measuring chamber 88.

In the embodiment of the invention illustrated in FIG- URE 7 a vari-able orifice valve 200 is disclosed which causes the foot valve 86 to open different amounts as determined by the pressure within the measuring chamber 88. The orice valve 200 may be substituted for the valve 144 and is identical to the valve 144 except that a frustoconical valve head 202 is provided rather than the cylindrical valve head 160. As indicated in FIGURE 7, the valve head includes a narrow cylindrical upper portion 204 which is loosely fitted within the orifice 206 so as t provide the desired -30 thousandth of an inch therebetween which is necessary to provide the initial valve opening pressure. As the valve head 202 and foot valve moves upwardly in response to an increase of pressure within the measuring chamber 88, a frusto-conical portion 208 of the valve head 202 enters the orifice 206 thereby increasing the clearance between the orifice and the valve head 202 permitting the liquid to more rapidly fiow past the variable orifice valve 200 thereby reducing the pressure in cham-ber 88 and lowering the valve head 202 and ring 122 of the foot valve 86. Lowering of the ring 122 causes the fiow passage between the ring 122 and lip 123 to be restricted in size.

Thus, the use of a frusto-conieal valve head 202 within the orifice is utilized to regulate the size 0f the fiow passages through the foot valve in direct proportion to pressure charges within the measuring chamber. It is also t0 be understood that the cylindrical upper portion 204 can be omitted or be wider or narrower than illustrated so as to control the amount of upward movement permitted of the valve head 202 before the pressure control of the frusto-conical portion 208 begins to take effect.

Although the preferred embodiment of the invention illustrates a double-opening valve, it will be understood that the invention is to be considered broad enough to cover a multiple-opening valve wherein additional rings are disposed between the ring 122 and the lip 123 and are interconnected so that each ring can be lifted from the next following ring in step-by-step progression during opening of the valve.

From the foregoing description it will be apparent that the liquid dispensing apparatus of the present invention includes a double-opening foot valve which is -first partially opened to direct a solid stream of liquid centrally through the valve thereby preventing the entrapment of an air bubble within the liquid, and immediately thereafter, under the control of the variable orifice valve, further opens the foot valve to reinforce the central cylindrical stream with an outer stream thereby providing a very large exit area so that a large quantity of liquid will fiow past the foot valve at a relatively slow speed thereby minimizing turbulence with the result that foaming is reduced to a minimum. The apparatus also includes a pressure responsive variable orifice valve which controls the opening of the foot valve so that full opening of the foot valve occurs immediately after partial opening thereof even at very low operating pressures.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention as set forth in the appended claims.

Having completed a detailed description of the invention so that those skilled in the art could practice the same, I claim:

1. In a liquid dispensing apparatus comprising means defining a variable capacity liquid measuring chamber which includes a filling tube having an inlet end and an outlet end; means for filling said chamber with a quantity of liquid; means defining a double-opening valve movable between a closed position, a partially open position permitting a centrally disposed relatively small diameter substantially cylindrical stream of liquid to ow through the outlet end of the filling tube, and a fully opened position permitting a large diameter stream of liquid to fiow through the outlet end of the filling tube and to supplement the small diameter cylindrical stream; means for decreasing the size of said liquid measuring chamber thereby increasing the pressure within said chamber; valve opening means in said measuring chamber connected to said valve for controlling the position of said valve; said double-opening valve being a foot valve; means defining an orifice valve at the inlet end of said filling tube, means defining an orifice in said orifice valve, an orifice `valve head associated with said orifice and having a relatively small clearance when disposed fully within said orifice, said orifice `valve head being movable between a partially closed position and an open position to vary the size of said orice from a substantially closed restricted condition to a substantially unrestricted open condition, and means connecting said orifice valve head to said foot valve to open both of said valves simultaneously.

2. An apparatus according to claim 1 wherein said orifice 4valve head includes a large diameter cylindrical portion which remains within said orifice until after the foot valve has been moved from the closed to the fully open position.

3. An apparatus according to claim 1 wherein said orifice valve head includes a frusto-conical portion and wherein said frusto-conical portion enters said orifice after the foot valve has first moved from the closed position to the partially open position.

4. An apparatus according to claim 1 wherein said means for decreasing the size of said liquid measuring chamber decreases said chamber size at variable rates thereby varying the pressure within said chamber, and wherein said means for opening the foot valve controls the amount of opening of said orifice valve and said foot valve in direct proportion to the pressure changes in said measuring chamber.

5. An apparatus according to claim 1 wherein said means for decreasing the size of said liquid measuring chamber decreases said chamber size at variable rates thereby varying the pressure within said chamber, wherein said orifice valve head includes a large cylindrical portion which remains within said orifice until after the foot 9 10 Valve has been moved from the closed to the fully open References Cited position, and wherein said means for opening the foot UNITED STATES PATENTS valve fully opens the foot valve at low pressures and re- 519,307 5 /1894 Perkins 141 128 tains said foot valve at said fully open position independ- 3,128,915 4/ 1964 Matter 222-355 ently of pressure variations in said chamber that are 5 3,295,722 1/1957 Gordon et 211 222-52 greater than Said 10W presslfre' ROBERT B. REEVES, Primary Examiner.

6. An apparatus according to clalm 5 wherein the clearance between said orice and said orifice valve when H S LANE Asslstam Examiner in the partially closed position is between about 15-30 10 US @1 XR. thousandths of an inch. 141-147

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