US2566372A

US2566372A - Safety shutoff control system for gas burners

Info

Publication number: US2566372A
Application number: US669037A
Authority: US
Inventors: William A Ray
Original assignee: General Controls Co
Current assignee: General Controls Co
Priority date: 1946-05-11
Filing date: 1946-05-11
Publication date: 1951-09-04
Anticipated expiration: 1968-09-04

Description

w. A. RAY 2,566,372

SAFETY SHUTOFF CONTROL SYSTEM FOR GAS BURNERS 4 Sheets-Sheet 1 Sept. 4, 1951 Filed May 11, 1946 2 2 4 9 0 N 7.0 1" P Q a lV/LLMM A.

3mncntor:

attorney Sept. 4, 1951 w. A. RAY ,3

SAFETY SHUTOFF CONTROL SYSTEM FOR GAS BURNERS Filed May ll. 1946 4 Sheets-Sheet 2 6k Va 8a WILL/AM A. PAY,

lnnentor (Ittormeg Sept. 4, 1951 w. A. RAY 2,555,372

' SAFETY SHUTOFF CONTROL SYSTEM FOR GAS BURNERS Fil ed lay 11. 194:6 4 Sheets-Sheet s I :12 FY o- & 33

ISnvemtor: L UAM A, ,Q

Gttomeg,

Sept. 4, 1951 w. A. RAY

SAFETY SHUTOFF CONTROL SYSTEM FOR GAS Filed May 11. 1946 BURNERS 4 Sheets-Sheet 4 3nrocnlor WILL/AM A PAY,

(I Home Patented Sept. 4, 1951 SAFETY SHUTOFF CONTROL SYSTEM FOR GAS BURNERS William A. Ran-North Hollywood, Calif., assignor to General Controls 00. poration of California Glendale, CaliL, a cor- Application May 11, 1946, Serial Nassau-1 12 Claims. (cuss-117.1)

My present invention relates to gas-burner control systems of the safety-shutoii' type; and mor particularly to such systems as include a main burner and a pilot burner, and means for shutting-off supply of fuel to the main burner while lightin the pilot burner. To accomplish this result it has been proposed to employ a valve of the manually-rotatable plug type, in conjunction with a supplementary or safety valve, manually openable only while the plug is in position to obstruct flow to the main burner, for supplying fuel to the pilot burner; means responsive to the flame of the pilot burner being provided for maintaining the supplementary valve in its manually-opened condition while the flame exists.

A main object of this invention is to provide an improved burner control system wherein the safety valve or valves are of the automaticallyoperable type, .as distinguished from the "manual-reset valve employed in the above-mentioned prior-art-system.

Another object is to provide a system of the character described wherein th various conditions of the system, including one in which supply of fuel to both burners is mechanically shut off, are controlled through the medium'of a single manual-actuating means or handle.

For full understanding of the invention, and further appreciation of its objects and advantages, reference is to be had to the following detailed description and accompanyin drawing, and to the appended claims.

In the drawing:

Figure 1 is a plan view of a combination valve structure of thepresent invention;

Figures 2 and 3 are sectional views taken respectively along the lines 2-2 and 3'3:ot Fig. 1;

Figures 4 and 5 are fragmentary-sections taken respectively along the lines 4-! and 5-5 of Fig. 2;

Figures 6 and 6a are fragmentary sections taken, respectively, along the lines l6 and Sci-Ga of Fig. 2, showing the flow-controlling passages in the upper and lower sections of the plug valve 20:

Figures 7, 7a and 8, 8a are views similar to those of Figs. 6, 6a with the plug =23 in moved positions; 7

Figure 9 is a graph illustrating the various flowcontrolling functions of the plug 23;

Figure 10 is a diagrammatic view of azburner control system embodying this invention, and including the valve structure illustrated in Figs. 1 to 8;

Figure 11 is a view, corresponding generally to that of Fig. 2, of a modified form of combination valve structure;

Figure 12 is a diagrammatic view of a modified form of burner control system according to this invention, and including the valve structure illustrated in Fig. 11;

Figures 13 and 14 are diagrammatic views of still further modified forms of burner control systems according to this invention; and

Fi ure 15 is a fragmentary section of the plug valve as modified for use in the systems of Figs. 13 and 14.

Referring first to Figs. 1-8 of the drawing, the combination valve structure shown in Figs. 1, 2 and 3 comprises a manually-operable valve structure and an electromagnetic valve, generally indicated in Fig. l by the numerals 20 and 2|, respectively. In Fig. 1, the vertical arrows indicate the direction of main ilow through the valve 20, and the horizontal arrows the direction of "flow through valve 2 I.

The valve structure 20 comprises a casing 22 having a tapered bore or seat for a rotatable tapered plug 23 which is maintained in seated condition by the force of a sprin 24 compressed between the bottom of the plu and a plate 25 covering the open bottom end of the casing.

i Through thelower portion or section of the plug 23 is a main opening 26 (Fig. 3) which, when the plug is turned through from its position shown in Figs. 2 and 3, registers with an inlet and an outlet opening 21 and 28 (Fig. 31 in the casing. In the side surface of the upper portion of the plug is a groove 29 which cooperates with an inlet and an outlet passage 30 and 3| respectively, (Fig. 2) in the casing.

In a thickened portion of the side wall of casing 22 is a vertical bore 32 which joins the passage 3l; the bore being restricted toward its upper end to form a seat for a-ball 33 (urged toward seating position bythe force of a spring 34 backed by an adjusting screw 35) which controls communication between the passage 31 and another passage 38 branched from bore 32. Resting on the ball 33 is an actuating pin 31 which is closely guided in a relatively long opening through the top wall of the casing.

The flat-sided stem 38 of the plug 23 is within an elongated opening, through the top wall of the casing, encompassed by a tubular extension 33. Within this extension is a cupped member 4|] having in its bottom wall an opening fitting the plug-stem 38; four spaced fingers 41 extending outwardly and upwardly from the mouth of the 3 cup, as is better seen in Fig. (for the sake of clarity, the extension 39 is not shown in this figure). Around the extension 39 is a sleeve 42, to the flared bottom end of which a ball-race 43 is secured as by welding. This race, together with balls 44, forms a ball-bearing support for the sleeve 42 and is held in place by a snap-ring 45 cooperating with a shoulder formed on the extension 39. Providing a. lost-motion connection between the sleeve 42 and the plug-operating member 40 is an arm 46 the extremities of which are received in conforming slots in the sleeve;

. the inner or middle portion of the arm lying between the fingers 4| of member 49. Secured to the arm 46, by a screw 41, is a handle 48 comprising a cupped portion fitting over the sleeve 42 and having projections 49 formed to provide inner recesses for receiving the extremities of arm 46; an extra projection 49 being provided so that, if desired, the handle may be attached at another position 90 to that shown. Extending integrally from the ball-race 43 is a lug 50 which is cooperable with a lever 5| pivoted in a recess in the casing (Fig. 4) and in engagement with the head of the ball-valve pin 31. From the foregoing it is apparent that the plug 23 can be rotated by manipulation of handle 48, and when the handle is turned from its shown position through a small angle in a clockwise direction (as viewed in Fig. 5). the valve-ball 33 is unseated; the force of spring 34 sufllcing to return the handle to its original position, when released, due to the lost-motion connection between the arm 46 and fingers 4|,

and also due to the anti-friction mounting of the handle assembly.

As can be seen in Figs. 6, 7 and 8, the groove 29 in the upper section of plug 23 extends only'partway around, so that when the plug is in the position of Fig. 6 communication between the passages 30 and 3| is obstructed; the main opening 26 through the lower section of the plug (shown in Figs. 6a, 7a and 8a) then also being in flowaverting position. When the plug is rotated in a clockwise direction through 90 from the position of Figs. 6, 6a to that of Figs. 7, 7a, fluid can pass through both sections of th plug; and when the plug is rotated through an additional 90 to the position of Figs. 8, 8a (which corresponds to that shown in Figs. 2 and 3), fluid can still pass through the upper section,.but the main flow is obstructed. The positions of the plug-openings, when the plug is rotated through an additional small angle to unseat the valve-ball 33 as described above, are indicated by the broken lines in Figs. 8, 8a. These conditions of the plug valve ar graphically illustrated in Fig. 9 wherein the heavy lines bearing the legends Main Valve On and "Pilot Valve On indicate flow through the main openings 21-28, and through passages 3|I3|, respectively; the legend By-Pass Open referring to the unseated condition of the valveball 33. The straight lines in Fig. 9 numbered generally 6, 1 and 8 relate t the like-numbered,

figures of the drawing, as well as to the lower sections 6a. 1a and 8a; also, the solid and brokenline positions of the handle 48, as shown in Fig. 5, correspond in angular relation to the numbered lines of Fig. 9.

The electromagnetic valve 2| comprises a casing 52 which is secured to the casing 22 of plug valve 29 by screws 53 (Fig. 1) in flanged portions of the two casings. In the casing 52 is an inlet passage 54 (in register with the passage 3| of the plug valve) from which a branch passage 55 leads to a valve chamber 56 above the casing. In this chamber is a disk-shaped closure 51, of magnetlzable material, which normally has three-point support on a valve seat 58 (raised around an outlet port 59) and a pair of pins 60. By this arrangement, generally disclosed in my Patent No. 2,294,421 of September 1, 1942, only a small amount of power is required to eflect initial tilting action of the closure on its seat; the resultant relief of fluid pressure in the chamber 56 facilitating movement of the closure to its fully-open position. 'The port 59 leads to an outlet passage 6| which is also in communication with the passage 36 of plug valve 20.

: On top of the casing 52 is an electromagnet comprising an inverted cup-shaped magnetic shell 62 to which is welded a flanged supportingring 63, also of magnetic material. A central core 64 is bolted to the top wall of shell 62, the tapered enlargement 65 of the core aflording intimate engagement between the parts. The bottom end of core 64 is formed to provide a polar enlargement 66, the pole-face of which is in the plane of the pole-face of shell 62 defined by the underside of its inwardly-turned flange 61. When the electromagnet is energized by passage of current (preferably D. C.) through its coil 68. the closurearmature 51 is attracted to open position as described above (against gravity, and against fluid pressure acting on its top when fluidis supplied to the valve chamber 56 by way of the inlet passages 5455) The system of Fig. 10 includes apparatus corresponding to the combination valve structure shown in Figs. 1-8a and described hereinabove; the parts therefore being designated in Fig. 10 by the same reference numerals; the part indicated at 33'. however, being intended to represent the complete valve constituted by ball 33. The other of these parts in Fig. 10 are: plug valve 29, electromagnetic valve 2|, coil 69 of valve 2|, pin 31 for actuating valve 33', handle-lug 59 cooperable with pin 31, and passage 6| by-passing'valve 2|. The system of Fig. 10 further includes a conduit 1|1|' for supplying fluid fuel, such as ordinary gas, to a main burner 12. Connected in series in this conduit is a pair of valves, one of them (indicated at 29) being the main or lower section (controlled by the plug opening 25) of the plug' valve, the other an electromagnetic valv 13 which may be of the same type as valve 2| (but of greater flow-capacity), or of the electricallycontrolled fluid-pressure-operated typ such as the diaphragm valve disclosed in my Patent No. 2,294,693 of September 1, 1942.

The inlet passage 39 of the upper section of the plug valve is connected by a pipe 14 to the conduit 1| ahead of the valve 13, the outlet passage 3| being connected directly to the inlet 54 of the electromagnetic valve 2|, as shown in Fig. 2. From the outlet of valve 2| a pipe 15 leads to a pilot burner 16, the flame 11 of which serves as means for igniting the main burner. Arranged to be heated by another flame 11' of the pilot burner is a thermoelectric generating device 18 comprising a plurality of thermocouples connected in series to form a thermopile. The generating device 19 is connected by wires 19 to the energizing coil 89 of valve 13 in series with an automatic control device 9| which, for example, may be a thermostat responsive to the temperature of a space heated by the main burner 12. Branching from wires 19 are other wires 82 which connect the coil 68 of valve 2| directly to the generator. It is to be understood that in place of the thermoelectric generating device other well-known generating means, influenced by the pilot-burner flame, may be employed; as, for example, a conventional source of electricity controlled by a thermal cut-out, or a photoelectric system responsive to the flame.

In Fig. 10. the plug valve is in the condition shown in Figs. l-5 and Figs. 8, 8a; the handle-lug being adjacent pin 31. Since flame is shown at the pilot burner, the valve 2| is energized and in open condition; the valve 13 being either open or closed depending upon the condition of thermostat 8 I, however, no fuel can now pass to the main burner since the main plugopening 26 is in flow-averting position. To establish normal operation of the burner system, the valve plug is rotated in a counterclockwise direction through 90 to the position of Figs. 7, 7a; the valve 13 then automatically controlling fuel flow to the main burner in accordance with the requirements of the thermostat. If it is desired to completely discontinue operation of the system (as during a season when heating is not required), the plug is turned to the position of Figs. 6, 6a so that flow through both sections of the plug valve is obstructed; the valves 13 and 2| also closing due to the resultant cessation of generation of electricity by the device 18 when the pilot flame i1 is extinguished, so that positive 100% shut-off of the fuel is ensured.

In the event that during normal operation of the system (with plug in Figs. 7, 7a position) the pilot-burner flame is extinguished, both of the valves 13 and 2| close as described above. To lightthe pilot burner and thereby reinitiate operation of the system, the plug is rotated to 1 the position of Figs. 8, 8a and then slightly beyond that position (in clockwise direction) to effect opening of the by-pass valve 33 by the handle-lug 50; fuel flow to the main burner then being obstructed not only due to the fact that valve I3 is deenergized, but also due to the flowaverting position of the main plug-opening as shown in broken lines in Fig. 8a. The by-pass valve 33 is maintained in open position for an interval, following relighting of the pilot burner by any convenient means, long enough to permit generation of electricity by the device 18 in an amount suflicient to effect automatic opening of the valve 2| (which opening is evidenced by an audible click"); whereupon the plug-valve handle is released and returns (under the force of the bias spring of valve 33') to the position shown in solid lines in Fig. 5. If normal or automatic operation of the system is then desired. the plug is rotated .back to the position of Figs. 7, 7a. as described in the preceding paragraph. By the series arrangement of the valves 20 and 13 in conduit 1| fuel flow to the main burner is obstructed if either of these valves is closed. and it is to beunderstood that their order of arrangement in the conduit can be reversed (as by removing valve 13 from conduit 1| and connecting it in conduit 1| between the main burner and valve 20) without in any way affecting operation of the system.

In the combination valve structure of Fig. ii, the plug valve 20 is identical in construction with that'shown in the preceding figures; the electromagnetic valve, indicated here by the numeral 2|, being the same as valve 2| except in regard to the outlet passage which in valve 2| is enlarged to provide a chamber 6| the bottom wall 86. Inasmuch as this switching device is of conventional construction and forms, perse, no part of the present invention, it suflices to state that when the actuating button 81 is moved downwardly by gas pressure in chamber 6| acting through the medium of the diaphragm 85, a bridging element 88 is snapped into engagement with contacts 89, and when the pressure is reduced a reverse action occurs.

The burner control system shown in Fig. 12 includes the modified combination-valve-structure of Fig. 11 and differs in other respects from the system of Fig. 10 only by the provision of a separate source of electricity for energizing the coil of valve 13. In Fig. 12, the thermoelectric generating device 19 is shown connected to the coil 63 of valve 2|, only, by wires separate Wires 9|, having terminals 92 for the ordinary electric-service source, connecting the thermostat 8| to the coil 80 of valve 13 in series with the contacts 89 of switching device 88.

The operation of the system of Fig. 12 is, in effect, the same as that of the System of Fig. 10, since upon extinguishment of the pilot-burner flame, and resultant closing of valve 2 the valve 13 is deenergized due to the opening of contacts 89. It is to be observed that in Fig. 11 the switching device 86 is in normal or open condition, while in Fig. 12 it is shown as being closed due to the existence of gas pressure in chamber 6 The systems of Figs. 13 and 14 are similar to each other and each includes a plug valve, indicated at 20' in these figures, which difiers from the plug valve 20 only in the fragmentary portion of its casing 22', shown in Fig. 15, wherein the outlet passage 3| and passage 36 are each provided with a threaded

connection

93 and 94, respectively. The systems of Figs. 13 and 14 differ essentially from those of Figs. 10 and 12 mainly by the omission of the pilot-burner control valves 2| and 2| of those figures; the valve 13 being arranged to control supply of gas to both the main burner and the pilot burner, and serving as a, 100% safety shut-off. For that purpose, the inlet passage 30 of the upper section of the plug valve is connected by a pipe 95 to the conduit II at the downstream side of valve 13; the connection 94 (here, the inlet connection) of ball-valve 33 being joined to the conduit H ahead of valve 13 by another pipe 96. Hence, when valve 13 is closed, gas can be supplied to the pilot burner only by manual opening of valve 33'. The systems of Figs. 13 and 14 are associated with a boiler (assumed to be heated by the main burner 12) of which a fragmentary wall-section is indicated at 91.

In Fig. 13, the thermoelectric generating device 18 is connected by wires 98 directly to the coil 90 of valve 13, so that only in the event of extinguishment of the pilot-burner flame does the valve 13 close to effect the 100% shut-oil. Connected in the pilot-burner supply pipe 15 is a thermostatic valve 99, of conventional construction, which is mounted in an opening through the boiler-wall 91; this valve serving to shut-off the pilot-burner gas supply in the event that the boiler temperature reaches a dangerously-high limit, so that the system is then rendered inoperative due to the extinguishment of the pilot-burner flame;

In Fig. 14, there is shown, mounted in an opening through the boiler-wall 91, a compound thermostatic device I00 which may be the same as that disclosed in my PatentNo. 2,312,479 of March 2, 1943. This device comprises a thermal 7 bulb lll operatively connected by a capillary tube ll! to a pressure-operated valve I03 inserted in conduit H between the main burner and the valves 23' and 13; the device also comprising a bimetallic thermostat I04 responsive to the temperature of the thermal bulb and hence also to that of the boiler. The thermoelectric generating device 18 of Fig. 14 is connected by wires I05 to the coil 80 of valve 13 in series with the contacts of thermostat i. The units of the thermostatic device llll are so adjusted that the valve I03 is operated between open and closed positions to normally effect maintenance of desired temperature in the boiler; the contacts of thermostat I" opening only in the event that the boiler temperature rises above a safe limit, whereupon the system is rendered inoperative due to the resultant closing of valve 13 and extinguishment of the pilot-burner flame.

In the systems of Figs. 13 and 14 the relighting of the pilot burner (while flow to the main burner is positively prevented) is accomplished in the same manner as described in connection with the systems of Figs. and 12; gas being temporarily supplied to the pilot burner, when ball-valve 33' is opened, through by-pass pipe 96 and the outlet passage 3! (represented in Figs. 13 and 14 by a pipe 3!) of the plug valve; the supply then being by way of pipe 95 and the recess 29 of the plug valve when valve 13 opens in response to the heating of the thermoelectric generating device.

The feature of providing a lost-motion connection between handle 48 and plug 23 to avoid the possibility of valve-ball 33 being retained in open position due to friction between the. plug and its seat, is claimed in application Serial No. 220,033 which on April 9, 1951 was filed as a division of the present application.

The embodiments of my invention herein shown and described are obviously susceptible of modification without departing from the spirit of the invention, and I intend therefore to be limited only by the scope of the appended claims.

I claim as my invention:

1. In a burner control system: a main burner; a conduit for supplying gas to said main burner; a manually operable valve in said conduit for controlling flow therethrough; means for operating said manually operable valve; a pilot burner for igniting said main burner; a supplementary valve for temporarily supplying gas to said pilot burner and operable to open position by said operating means only while the manually operable valve is in position to obstruct flow to the main burner, said supplementary valve being biased to closed position and capable of supplying gas only while the operating means is manually held; and valve means opening in response to the flame of the pilot burner and capable only while said flame exists of supplying gas to the pilot burner.

2. In a burner control system: a main burner; a conduit for supplying gas to said main burner; a manually operable valve in said conduit for controlling flow therethrough; means for operating said manually operable valve; a pilot burner for said main burner; a supplementary valve for temporarily supplying gas to said pilot burner and operable to open position bysaid operating means only while the manually operable valve is in position to obstruct flow to the main burner, said supplementary valve being biased to closed position and capable of supplying gas only automatically operable to normally control the flow; means for operating said manually operable valve; a pilot burner for igniting said main burner; a supplementary valve for temporarily supplying gas to said pilot burner and operable to open position by said manual operating means only while the manually operable valve is in condition to obstruct flow to the main burner, said supplementary valve being biased to closed position and capable of supplying gas only while said operating means is manually held; means for supplying gas to the pilot burner while said supplementary valve is closed; electrical means for rendering said last-named means effective; and means influenced by the flame of the pilot burner for generating energy for said electrical means.

4. In a burner control system: a main burner; a conduit for supplying gas to said main burner; a pair of valves arranged in series in said conduit for controlling flow therethrough, one of the valves being manually operable, the other being automatically operable to normally control the flow means for operating said manually operable valve; 3. pilot burner for igniting said main burner; valve means responsive to the flame of said pilot burner and adapted to supply as to the pilot burner only while said flame exists; and a supplementary valve for by-passing said valve means so as to supply gas to the pilot burner when said flame is extinguished, said supplementary valve being operable to open position by said operating means only while the manually operable valve is in condition to obstruct flow to the main burner, said supplementary valve being biased to closed position and capable of supplying gas only while the operating held.

5. In a burner control system: a main burner; a conduit for supplying gas to said main burner; a pair of valves arranged in series in said conduit for controlling flow therethrough, one of the valves being manually operable. the other being electrical and automatically operable to normally eflect on-and-ofi' control of the flow; means for operating said manually operable valve; a. pilot burner for igniting said main burner; normallyclosed electrically-operated valve means for supplying gas to said pilot burner; means influenced by the flam of the pilot burner for generating electrical energy for operating said valve means to open positionand for maintaining it in that position only while said flame exists; a supplementary valve for by-passing said valve means so as to supply gas to the pilot burner when said flame is extinguished, said supplementary valve being operable to open position by said operating means only while the manually operable valve is in condition to obstruct flow to the main burner, said supplementary valve being biased to closed position and capable of supplying gas only while the operating means is manually held; and means while the operating means is manually held; for efl'ecting closure of said other of said mainmeans is manually burner-control valves upon extinguishment of the pilot-burner flame.

6. A burner control system, as defined in claim 5, wherein said means for effecting closure of the other of the main-burner-control valves upon extinguishment of the pilot-burner flame comprises electrical switching means responsive to the pressure of the gas supplied to the pilot burner.

7. In a burner control system: a main burner; a conduit for supplying gas to said main burner; a pair of valves arranged in series in said conduit for controlling flow therethrough, one of the valves comprising a manually-rotatable plug, the other being electrically and automatically operable to normally effect on-and-oil control of the flow; means for operating said plug valve; 9. pilot burner for igniting said main burner; a pipe for supplying gas to said pilot burner and connected to said conduit ahead of said mainburner-control valves; normally-closed electrically-operated valve means for controlling flow through said pipe; means influenced by the flame of the pilot burner for generating electrical energy for operating said valve means to open position and for maintaining it in that position only while said flame exists; and a supplementary valve for by-passing said electrical valve means so as to efiect supply of gas to the pilot burner when said flame is extinguished, said supplementary valve being operable to open position by said operating means only while said plug is in position to obstruct flow to the main burner, said supplementary valve being biased to closed position and capable of maintaining the supply of gas only while the operating means is manually held.

8. In a burner control system: a main burner;

a pair of valves arranged in series in said conduit for controlling flow therethrough, one of the valves being manually operable, the other being automatically operable to open and closed position when respectively energized and deenergized; a pilot burner for igniting said main burner and connected to said conduit at the outlet side of a conduit for supplying gas to said main burner;

a pair of valves arranged in series in said conduit for controlling flow therethrough, one of the valves comprising a manually-rotatable plug, the other being electrical and automatically operable to normally efiect on-and-ofl control of the'fiow; a pilot burner for igniting said main burner; a pipe for supplying gas to said pilot burner, said pipe being connected to said conduit ahead of said main-burner control valves and to the pilot burner through flow-controlling passages in said plug valve; means for manually operating said plug valve to control flow to both the main burner and the pilot burner; normally-closed electricallyoperated valve means for controlling flow through said pipe; means influenced by the flame of the pilot burner for generating electrical energy for operating said valve means to open position and for maintaining it in that position only while said flame exists; and a supplementary valve for bypassing said electrical valve means so as to effect supply of gas to the pilot burner when said flame is extinguished, said supplementary valve being operable to open position by said operating means while said plug is in position to obstruct flow to the main burner only, said supplementary valve being biased to closed position and capable oi maintaining the supply of gas only while the operating means is manually held.

9. A burner control system. as defined in claim 8, including electrical means for eflecting closure of said other of the main-burner-control valves upon extinguishment of the pilot-burner flame.

10. In a. burner control system: a main burner; a conduit for supplying gas to said main burner;

said automatically-operable valve so that normally only when the same is open can gas pass to the pilot burner; means influenced by the flame of said pilot burner for generating energy for opening said automatically-operable valve and for maintaining it in open position only while said flame exists; means for operating said manuallyoperable valve; and a supplementary valve for supplying gas to said pilot burner when said automatically-operable valve is closed, said supplementary valve being operable to open position by said operatingv means only while the manually-operable valve is in condition to 019- struct flow to the main burner, said supplementary valve being biased to closed position and capable of supplying gas only while the operating means is manually held.

11. A burner control system, as defined in claim 10, including means, responsive to a heat condition resulting from the operation of said main burner, for independently effecting obstruction of as-flowto both the main and the pilot burner in the event that said condition becomes abnormal.

12. In a burner control system: a main burner; a conduit for supplying gas to said main burner; a pair of valves arranged in series in said conduit for controlling flow therethrough, one of the valves comprising a manually-rotatable plug, the other being electrical and automatically operable to open and closed positions; means for operating said plug valve; 9, pilot burner for igniting said main burner; a pipe for supplying gas to said pilot burner, said pipe being connected to said conduit at the outlet side of said automatically-operable valve and to the pilot burner through flow-controlling passages in said plug valve; means influenced by the flame of said pilot burner for generating electrical energy for opening said automatically-operabl valve and for WILLIAM A. RAY.

REFERENCES CITED The following references are of record in the file oi this patent:

UNITED STATES PATENTS Number Name Date 2,201,398 Grayson May 21, 1940 2,217,785 Betz et a1 Oct. 15, 1940 2,253,670 Wetzel et al Aug. 26, 1941 2,861,944 Jackson et al Nov. 7, 1944 2,371,351 Paille' Mar. 13, 1945 2,403,611 Ray July 9, 194$