US3392740A

US3392740A - Gas burner control device

Info

Publication number: US3392740A
Application number: US527258A
Authority: US
Inventors: Thomas P Fleer
Original assignee: Individual
Current assignee: Individual
Priority date: 1966-02-14
Filing date: 1966-02-14
Publication date: 1968-07-16
Anticipated expiration: 1985-07-16

Description

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July 16, 1968 Filed Feb. 14, 1966 T. P. FLEER GAS BURNER CONTROL DEVICE 2 Sheets-Sheet l [NI EN 7'02 7' 140M415 FL FEE July 16, 1968 'r. P. FLEER 3,392,740

GAS BURNER CONTROL DEVICE Filed Feb. 14, 1966 2 Sheets-Sheet 2 fi 1 II F76. 5 F/a. 95

IN l hvroz I'HOMAS I. FIFE-2 a 54411 United States Patent 3,392,740 GAS BURNER CONTROL DEVICE Thomas P. Fleer, Sunset Hills, Mo. (29 Black Oak Drive, St. Louis, Mo. 63127) Filed Feb. 14, 1966, Ser. No. 527,258 7 Claims. (Cl. 137-65) This invention relates to fuel flow control devices for gas burners which include a thermostatically controlled valve for controlling the on-and-off operation of a main burner and a manual reset cutoff valve responsive to pilot burner flame.

The primary object of the invention is to provide a generally new and improved safety control device for gas burners which is particularly compact and economical to manufacture.

A further object is to provide a gas burner control device having an on-and-off, thermostatically controlled valve controlling the flow of fuel to a main burner and an anterior, series-arranged, manual reset, cutoff valve responsive to pilot burner flame, in which both valves move slidably on surfaces intersected by fuel passages to control the flow through said device.

A further object is to provide a gas burner control device of the above character in which the on-and-otf valve and cutoff valve are rotated on a common axis and have arcuate surfaces which move slidably on cooperating arcuate surfaces intersected by the fuel passages these valves control.

A further object is to provide a fuel control device having an on-and-off, thermostatically controlled valve controlling the flow of fuel to a main burner and a manual reset cutoff valve, in which the on-and-off valve has a surface which is moved slidably in fluid sealing relationship on a cooperating surface between open and normal closed positions with respect to a fuel passage intersecting the cooperating surface, in which the valve surface and cooperating surface are sufficiently extensive to permit substantial further movement of the on-and-olf valve in a closing direction beyond its normal closed position while still maintaining closure of the intersecting fuel passage, and in which movement of the on-and-oif valve in a closing direction beyond its normal closed position effects the opening of the cutoff valve.

Further objects and advantages will appear from the following description when read in connection with the accompanying drawings.

In the drawings:

FIG. 1 is a longitudinal sectional view of a control device for gas burners constructed in accordance with the present invention, shown in a first operative position and schematicall associated with main and pilot burners;

FIGS. 2 and -3 are similar, longitudinal, sectional views of thecontrol device shown in second and third operative positions;

FIG. 4 is a cross-sectional view of the control device taken along line 44 of FIG. 1;

FIG. 5 is a longitudinal sectional view of a second form of control device constructed in accordance with the present invention, shown in a first operative position;

FIG. 6 is a left end elevational view, with parts sectionalized, and is taken along line 66 of FIG. 5;

FIG. 7 is a right end elevational view of the control device shown in FIGS. 5 and 6;

FIG. 8 is a fragmentary cross-sectional view taken on line 88 of FIG. 5;

FIG. 9 is a fragmentary cross-sectional view taken on line 9-9 of FIG. 5;

FIGS. 10 and 11 and 8A and 9A are right and left end elevational views and cross-sectional views, respectively, showing the device of FIGS. 5 to 9 in a second operative position; and

3,392,740- Paterited July 16, 1968 ICC FIGS. 8B and 9B and 12 are cross-sectional views and a right-end view, respectively, showing the device of FIGS. 5 to 9 in a third operative position.

Referring to the drawings in more detail, the form of control device shown in FIGS. 1 to 4 inclusive comprises an elongated valve body 10 having a longitudinal bore 12 extending therethrough. Slidably fitted in bore 12 is a cylindrical main burner control valve 14 and a cylindrical manual reset cutoff valve 16. Valve 14 has an integral reduced diameter portion 18 at the right end thereof which under certain conditions, as shown in FIGS. 1 and 2, abuts the left end of valve member 16. The reduced diameter portion 18 provides an annular space 19 for a purpose to be described. Valve member 16 also has an intermediate reduced diameter portion 20 which forms an annular grove and a shoulder 22.

Valve body 10 is also provided with an inlet passage 26, a main burner outlet passage 28, and a pilot burner outlet passage 30, which passages intersect the longitudinal bore 12. Gas is conducted to the inlet passage 26 from a source of supply through a conduit 32, and fuel is conducted from main and pilot

burner outlet passages

28 and 30 to a main burner 34 and a pilot burner 36 through fuel conduits 38 and 40, respectively.

The sliding fit of

valves

14 and 16 in bore 12 is such that the wall of the bore and engaging surfaces of the valves are in fluid sealing relationship, and the ends of bore 12 are closed against fluid leakage to the exterior irrespective of the operative positions of the valves, whereby the intermediate portion of bore 12, in essence, forms a chamber intersected by the

inlet passages

28 and 30. Communication between an intersecting fuel passage and the chamber is cutoff when the arcuate surface of a valve overlies the passage. A fluid sealing lubricant is preferably applied to the surfaces of the valves and the wall of bore 12.

Attached to the left end of the valve body 10 is a solenoid actuator 42 having a reciprocating plunger 44, a plunger stop member 45, and a winding 46. The solenoid is attached to the end of valve body .10 by scerws 48, and the plunger 44 is arranged concentric with bore 12 and

valves

14 and 16. The solenoid plunger 44 is provided with a collar 50 and a reduced diameter right end portion 52, the end of which enters a bore 54 in the left end of valve 14 in loose fit relationship and is connected to valve 14 by a cross pin 56. The cross pin 56 is press fitted into a transverse bore through valve 14 and is loosely fitted in a transverse bore in the reduced diameter plunger portion 52.

The solenoid plunger 44 and the connected valve 14 are biased toward the right by a conical spring 58, the rightward movement of plunger 44 and connected valve 14 being limited by the engagement of collar 50 on plunger 44 with the downwardly extending legs 60 of a pivoted lever generally indicated at 62. The lever 62 is disposed in a longitudinally extending slot 64 formed in the upper wall of valve body 10 at its left end and is pivotally mounted on a horizontally arranged pivot pin 66 press fitted in the valve body 10. The lever 62 is also provided with an upwardly extending handle 68 by which the lever may be rotated manually. The lever 62 is biased in a clockwise direction by a relatively strong spring 70, and a stop element 72 on lever 62 engages the upper surface of valve body 10 to limit the clockwise rotation of lever 62 under the urging of spring 70 to the position shown in FIGS. 1 and 3. The spring 70 is considerably stronger than the plunger return spring 58, so that the rightward movement of solenoid plunger 44 and connected valve 14 under the bias of conical spring 58 is definitely stopped when collar 50 engages the legs 60 of lever 62 when lever 62 is in the positions shown in FIGS. 1 and 3.

The cutoff valve 16 is biased in a leftward direction by a relatively strong spring 76 positioned between the right end of valve 16 and a cover plate 78 attached to the right end of the valve body by screws 80. A headed pin 82 threadedly engaged in the right end of valve 16 passes through an aperture in the cover plate 78 and definitely limits the leftward movement of valve 16 under the urging of spring 76.

Y The manual counterclockwise rotation of lever 12 causes downwardly extending legs 60 to engage the left end of valve 14, and continued counterclockwise rotation of the lever causes valve 14 and valve 16 to be moved toward the right to the position shown in FIG. 2, in which the annular groove 21 in valve 16 is positioned to receive a transversely movable detent pin 84. Detent pin 84 is slidably received in a transverse bore in the body and is moved from a retracted position, as shown in FIG. 1, to an extended position, as shown in FIGS. 2 and 3, by expansion of an expansible chamber 86. Upon contraction of the expansible chamber, the detent pin is returned to a retracted position by a return spring 87.

The expansible chamber 86 comprises a rigid outer cup member 88 attached to the valve body by screws 89 and an inner flexible cup member 90. The space between the bottoms of inner and

outer cup members

88 and 90 communicates with a bulb 91 through a capillary tube 92. The bulb 91, the capillary tube 92, and the space between the bottoms of

cup members

89 and 90 form a sealed system containing a high boiling point liquid such as mercury.

The solenoid winding 16 is connected across a source of electrical power by a circuit controlled by a line switch 73 and a thermostatic switch 74 (space thermostat). The thermostat 74 is responsive to the temperature of a space being heated by main burner 34 and effects the on-andoff energization of solenoid 42 in accordance with heat riquirements to maintain a predetermined space temperature. The solenoid 42 is shown in FIG. *1 in a deenergized position. When energized, the plunger 44 and connected main burner valve 14 are moved toward the left until the plunger 44 engages plunger stop member 45, as shown in FIG. 3.

Operation of first form shown in FIGS. 1 to 4 In FIG. 1 the device is shown in an off condition. In this condition, the line switch 73 being open, the solenoid 42 is de'energized and the main burner control valve is biased by spring 58 in its normal closed position with respect to main burner fuel outlet passage 28. Also, in this condition, the detent pin 84 is retracted and the cutoff valve 16 is biased in a closed position with respect to fuel inlet passage 26.

To operate the main and pilot burners the lever 62 is manually rotated counterclockwise to the position shown in FIG. 2 and is held in this position. In rotating lever 62 to this position, the main burner control valve 14 is moved toward the right sufficiently to engage and move cutoff valve 16 toward the right sufficiently to align the annular groove 21 therein with detent pin 84 and to uncover fuel inlet passage 26. The pilot burner outlet passage 30 is also uncovered under these conditions so that fuel may now flow from inlet passage 26 through annular space 19 and through outlet passage 30 to pilot burner 36.

The pilot burner is now ignited by any suitable means and thereafter the bulb 91 becomes sufficiently heated by the pilot flame in a short time to effect the expansion of expansible chamber 86 and the extension of detent 84 into the annular groove 21 in cutoff valve 16. When this occurs the lever 62 may be released and the cutoff valve 16 will remain in an open (set) position by reason of the engagement of shoulder 22 thereof with extended detent pin 84. Upon release of lever 62, spring 70 will return main burner fuel control valve 14 to its normal closed position with respect to main burner outlet passage 28, as in FIG. 1, by reason of the engagement of collar 50 by legs 60 as the lever 62 returns in a clockwise rotation.

It will be noted, referring to FIG. 2, that valve 14, although moved beyond its normal closed position to effect opening of inlet passage 26 has a sufficiently extensive surface to still maintain closure of main burner outlet passage 28. This precludes the possibility of fuel flowing to the main burner while pilot burner 36 is being ignited. It is to be understood that while in the arrangement shown the pilot burner outlet 30 is closed by valve 16 when in the cutoff position shown in FIG. 1, it is not essential to safe operation that it be closed.

With the cutoff valve in an open (set) position, the line switch 73 is now closed. Energization of solenoid 42 will now occur upon a closure of thermostat 74, and such energization will effect the movement of main burner valve 14 from its normal closed position of FIG. 1 to its open position of FIG. 3 with respect to main burner fuel outlet 28. Fuel now flows from inlet passage 26 directly across the bore 12 and through main and pilot

burner fuel passages

28 and 30 as indicated by arrows. The main burner valve 14 will now be operated between its open and normal closed position under control of thermostat 74, and the main burner will be ignited by pilot burner flame each time the main burner valve is opened. Failure of flame at the pilot burner will result in contraction of expansible chamber 86, the retraction of detent 84, and the closure of fuel inlet passage 26 by cutoff valve 16 under the bias of relatively strong spring 76.

The form of control device shown in FIGS. 5 to 12 comprises an elongated valve body having a longitudinal bore 102 extending therethrough. Fitted for rotation in bore 102 is a cylindrical main burner control valve 104 and a cylindrical manual reset cutoff valve 106. The cutoff valve 106 has a semicylindrical portion 108, and the main burner valve 104 has an axially extending pin 110 disposed at a point spaced radially outward from its center which under certain conditions causes valve 106 to be rotated counterclockwise when valve 104 is rotated counterclockwise with reference to FIG. 7.

The valve body 100 is further provided with a fuel inlet passage 112, a main burner fuel outlet passage 114, and an intermediate pilot burner fuel outlet 116, which passages intersect bore 102 forming ports in the wall thereof. The main burner control valve 104 has a longitudinal groove 118 formed therein which is open at the left end of the valve. The

valves

104 and 106 are retained against axial movement in bore 112 by annular grooves and ball-end set screws 122.

Fuel inlet passage 112 is closed when cutoff valve 106 is in the position shown in FIGS. 5 and 8, with the arcuate surface of its semicylindrical portion overlying the intersecting passage 112, and is open when the valve 106 is rotated to the position shown in FIGS. 8A and 8B. Main burner fuel outlet passage 114 is closed when longitudinal groove 118 in main burner valve 104 is out of register therewith, as shown in FIGS. 8, 9, 8A, and 9A, and is open when valve 104 is rotated to a position wherein groove 114 registers therewith, as shown in FIGS. 8B and 9B. The pilot burner outlet passage 116, being positioned in bore 112 between

valves

104 and 106, provides open communication between bore 112 and a pilot burner under all conditions. It will be understood, however, that the pilot outlet passage 116 may be positioned toward the left of the position shown so as to be controlled by valve 108 if this is desired. In the arrangement shown, the pilot outlet passage 116 may be positioned angularly around the bore 102 as desired, while if it is positioned leftward longitudinally so as to be controlled by valve 108, it will have to be positioned substantially in radial alignment with inlet passage 112.

At its right end valve 104 is provided with a reduced diameter portion 124 extending exteriorly of valve body 100. Mounted for rotation on portion 124 is a lever 126 having an arm 128 and an arm 130. Fixed in the right end of valve 104 near its periphery is a stop pin 132 extending exteriorly of the valve body and arranged to be engaged by arm 128 of lever 126 as the lever is rotated counterclockwise with respect to FIG. 7. There is also a stop pin 134 fixed in the right end of the valve body 100 arranged to be engaged by arm 130 of lever 126 as the lever is rotated counterclockwise. A relatively strong spring 136 biases lever 126 counterclockwise on valve portion 124 with its arm 128 bearing firmly against stop pin 132.

Mounted on a bracket 138 at the right end of valve body 100 is a solenoid actuator 140. The solenoid has a reciprocating plunger 142, the axis of which is arranged at a right angle to the axis of valve 104. A link 144 pivotally connected to the end of lever arm 128 and to the end of plunger 142 transmits reciprocating motion of the plunger to rotational motion of the lever 126. A relatively light return spring 146 biases plunger 142 in an extended position when the solenoid'is de-energized and also biases connected lever 126 in a counterclockwise direction with the lever arm 130 bearing against stop pin 134, as shown in FIG. 7. When the solenoid 140 is energized the plunger 142 is retracted downward, causing the lever 126 and valve 104 to be rotated clockwise to the position shown in FIG. 12. Clockwise rotation is imparted to valve 104 from lever 126 through the relatively strong spring 136 which bears at one end against lever arm 130 and at its other end against stop pin 132 in valve 104.

Attached to the left end of valve 106 and exterior of the valve body is a latch member 150. The latch member 150 is fixed on the end of valve 106 with pins or screws 152 for rotation with valve 106 and has a right angularly formed portion 153 adapted to engage a detent pin-154 under certain conditions. The valve 106 is biased in a counterclockwise direction, with reference to FIG. 6, against a stop pin 156 fixed in the valve body 100 by a relatively strong spring 158. The detent pin 154 is slidably mounted in a bore in an extension of valve body and is moved from an upwardly retracted position, as shown in FIG. 6, to a downwardly extended position, as shown in FIG. 10, by the expansion of an expansible chamber 160. Upon contraction of the expansible chamber, the detent pin is returned to a retracted position by a spring 162. The valve 104 is provided with a handle 164 attached to its reduced diameter position 124, whereby the valve may be rotated manually.

Operation of the second form shown in FIGS. 6 to 12 In FIGS. 5 to 9, the device is shown in an off condition. In this condition the solenoid 140' is de-energized, the main burner valve 104 is biased by spring 146 in a normal closed position with respect to outlet passage 114, as shown in FIG. 9, and cutoff valve 106 is biased in a closed position by relatively strong spring 158 with respect to inlet passage 112, as shown in FIG. 8. Also, in this position the pin 110 on valve 104 is closely adjacent the flat surface of the semicylindrical portion 108 of valve 106.

To supply fuel to the main and pilot burners, the valve 104 is manually rotated counterclockwise with respect to FIGS. 7 and 11, by means of handle 164, to the position shown in FIG. 11, and is held manually in this position. When manually rotating valve 104 to this position, valve 106 is moved to an Open position with respect to inlet passage 112, and latching portion 153 is moved into a latching position. Fuel may now flow, therefore, through inlet 112 to bore 102 and through pilot outlet passage 116 to the pilot burner. It will be noted, however, that valve 104 remains closed with respect to main burner outlet 114 by reason of its having been rotated in a closing direction beyond its normal closed position.

The pilot burner may now be ignited and in a short period of time expansion of expansible chamber 160' occurs and detent pin 16-2 is extended downwardly so as to be engaged by latch portion 153. When this occurs handle 164 may be released. Upon release of handle 164, cutoff valve 106 now remains open with respect to inlet passage 112, and main burner valve 104 is returned to its normal closed position by relatively strong spring 136. It will be noted, referring to FIG. 11, that when valve 104 is manually rotated counterclockwise, spring 136 is stressed by reason of its dead end bearing against lever arm and by reason of stop pin 134 which prevents further counterclockwise rotation of lever 126. When released, valve 104 returns under the bias of spring 136, in a clockwise direction with reference to FIG. 7, to a definite point at which the stop pin 132 on valve 104 engages the lever arm 128.

With cutoff valve 106 being held in an open position as a result of pilot flame, fuel will now flow to the main burner to be ignited by the pilot burner when the main valve 104 is moved to an open position, as shown in FIGS. 8B, 9B, and 12, by the solenoid each time the solenoid is energized. Failure of pilot burner flame will result in contraction of expansible chamber 160, retraction of detent pin 154, and closure of cutoff valve 106.

It is to be understood that in some arrangements it may be desirable to control the supply of fuel to the pilot burner by means other than the fuel flow control devices described. -In this case the pilot outlet passages 30 and 116 may be omitted.

It will be seen from the foregoing that I have provided a fuel flow control device meeting the safety requirements for gas burner operation, in which the fuel flows along a relatively short and substantially direct path from the inlet to outlet passages thereby reducing pressure drop encountered in conventional devices of this kind. This permits a substantial reduction in the size of passages and over-all size of the device.

I claim:

1. In a fuel flow control device for gas burners, a valve body, means forming a chamber therein having a wall, a fuel inlet port and a main burner fuel outlet port in said wall, an on-and-ofl valve controlling said outlet pont and a manually resettable cutoff valve controlling said inlet port, said valves being movably mounted in said body and each of said valves having a surface portion in said chamber contiguous with said chamber wall, which surface portions move slidably on said wall in fluid sealing relationship therewith between open and closed positions with respect to the ports they control as said valves are moved between open and closed positions, said ports being disposed so as to lie between said valve surface portions when said valves are in open position and said valves being arranged to be moved oppositely with respect to each other in opening and closing directions, spring means biasing said cutoff valve in a closed position, relatively light spring means biasing said on-and-olf valve in a closing direction and relatively strong springpressed stop means limiting its movement in a closing direction to a normal closed position, whereby said onand-oif v-alve may be moved manually in a closing direction beyond its normal closed position and upon release will be returned to its normal closed position, said surface portion of said on-and-off valve being sufficiently extensive to permit further movement of the valve in a closing direction beyond its normal closed position while still maintaining closure of said outlet port, means on said on-and-off valve operative to engage said cutoff valve and it move it to an open position when said onand-off valve is moved manually in a closing direction beyond its normal closed position, a solenoid actuator operative under certain conditions to open and hold open said on-and-oflf valve, manual means for moving said on-and-olf valve in a closing direction beyond its normal closed position to effect opening of said cutoff valve, and

movable condition responsive detent means operative under certain conditions to retain said cutoff valve in an open position.

2. A fuel flow control device as set forth in claim 1 in which said chamber comprises the intermediate portion of a bore extending through said valve body, in which said inlet and outlet ports are disposed in the wall of said intermediate bore portion, in which said valves are disposed in said bore and in which each valve has a cylindrical portion extending outwardly from said intermediate bore portion, which cylindrical valve portions are movably fitted in said bore in fluid sealing relationship.

3. A fuel flow control device as set forth in claim 1 in which said chamber comprises an intermediate portion of a bore extending through said valve body, in which said inlet and outlet ports are spaced axially in the intermediate bore portion, in which said valves are of cylindrical form and are fitted in said bore in movable fluid sealing relationship, in which adjacent end portions of said valves extend axially over the ports they control, in which the arcuate surfaces of said adjacent end portions of said valves are interrupted to form axial fuel passages between said ports and the inner adjacent ends of said valves when said surface interruptions are registered with said ports, and in which said valves are rotated between open and closed positions with respect to the ports they control.

4. A fuel flow conrol device as set forth in claim 1 in which said chamber comprises the intermediate portion of a bore extending through said valve body, in which said inlet and outlet ports are spaced axially in the intermediate bore portion, in which said valves are of cylindrical form, are fitted in said bore in movable fluid sealing relationship, and lie generally on opposite sides of said intermediate portion, in which said valves are moved slidably axially toward each other in a closing direction and outwardly away from each other in an open ing direction, and in which said solenoid actuator includes a reciprocating plunger operatively connected to the outer end of said on-and-off valve and arranged in substantially axial alignment with said bore.

5. A fuel flow control device as set forth in claim 1 which further includes a pilot burner outlet port in said wall positioned so as to lie between said valve surface portions when said on-and-off valve is moved manually beyond its normal closed position sufficiently to open said cutoff valve, and in which said condition responsive detent means is operative in response to the combustion of fuel passing through said pilot outlet to retain said cutoff valve in an open position, and is operative to release said cutoff valve to be returned to a closed position when such combustion ceases.

6. A fuel flow control device as set forth in claim 1 which further includes stop means for limiting the movement of said cutoff valve in a closing direction under its said biasing spring to a predetermined closed position.

7. A fuel flow control device as set forth in claim 1 which further includes a pilot outlet port in the wall of said chamber, in which said chamber comprises the intermediate portion of a bore extending through said valve body, in which said inlet and main burner outlet ports are spaced axially in said intermediate bore portion and said pilot outlet port is spaced axially from said main burner outlet port in the direction of said inlet port, in which said valves are of cylindrical form, are fitted in said bore in movable fluid sealing relationship and lie generally on opposite sides of said intermediate bore portion, in which said valves are moved slidably axially toward each other in a closing direction and outwardly away from each other in an opening direction, in which said means on said on-and-off valve engaging said cutoff valve comprises a reduced diameter portion at the inner end of said on-and-off valve whereby an annular space between said valves is formed when said reduced diameter portion engages the inner end of said cutoff valve, and said pilot outlet port being axially positioned in said bore so as to be axially in registry with said reduced diameter portion when said 0n-and-off valve is moved sufliciently beyond its normal closed position to open said cutoff valve.

References Cited UNITED STATES PATENTS 1,831,021 11/193'1 Markel .137

2,612,946 10/1952 Cobb 137-65 XR 2,637,390 5/1953 Perl et al 158--131 XR FOREIGN PATENTS 1,000,447 8/1965 Great Britain.

WILLIAM F. ODEA, Primary Examiner.

R. GERARD, Assistant Examiner.

Claims

1. IN A FUEL FLOW CONTROL DEVICE FOR GAS BURNERS, A VALVE BODY, MEANS FORMING A CHAMBER THEREIN HAVING A WALL, A FUEL INLET PORT AND A MAIN BURNER FUEL OUTLET PORT IN SAID WALL, AN ON-AND-OFF VALVE CONTROLLING SAID OUTLET PORT AND A MANUALLY RESETTABLE CUTOFF VALVE CONTROLLING SAID INLET PORT, SAID VALVES BEING MOVABLE MOUNTED IN SAID BODY AND EACH OF SAID VALVE HAVING A SURFACE PORTION IN SAID CHAMBER CONTIGUOUS WITH SAID CHAMBER WALL, WHICH SURFACE PORTIONS MOVE SLIDABLY ON SAID WALL IN FLUID SEALING RELATIONSHIP THEREWITH BETWEEN OPEN AND CLOSED POSITIONS WITH RESPECT TO THE PORTS THEY CONTROL AS SAID VALVES ARE MOVED BETWEEN OPEN AND CLOSED POSITIONS, SAID PORTS BEING DISPOSED SO AS TO LIE BETWEEN SAID VALVE SURFACE PORTIONS WHEN SAID VALVES ARE IN OPEN POSITION AND SAID VALVES BEING ARRANGED TO NE MOVED OPPOSITELY WITH RESPECT TO EACH OTHER IN OPENING AND CLOSING DIRECTIONS, SPRING MEANS BIASING SAID CUTOFF VALVE IN A CLOSED POSITION, RELATIVELY LIGHT SPRING MEANS BIASING SAID ON-AND-OFF VALVE IN A CLOSING DIRECTION AND RELATIVELY STRONG SPRINGPRESSED STOP MEANS LIMITING ITS MOVEMENT IN A CLOSING DIRECTION TO A NORMAL CLOSED POSITION, WHEREBY SAID ON-