US2319676A

US2319676A - Safety shutoff system

Info

Publication number: US2319676A
Application number: US334159A
Authority: US
Inventors: Stanley S Guelson
Original assignee: Milwaukee Gas Specialty Co
Current assignee: Milwaukee Gas Specialty Co
Priority date: 1940-05-09
Filing date: 1940-05-09
Publication date: 1943-05-18
Anticipated expiration: 1960-05-18

Description

Patented May 18, 1943 UNITED STATES PATENT oFFIce SAFETY SHUTOFF SYSTEM Stanley S. Guelson, Milwaukee, Wis., assignor to Milwaukee Gas Specialty Company, Milwaukee, Wis., a corporation of Wisconsin Application May 9, 1940, Serial No. 334,159 I 9 Claims. (01. 236--21) This invention relates to improvements in safety shutoff systems for fuel burners and the like.

One of the main objects of the invention is to provide an improved multi-controlled safety shutoff system which is operable to maintain a supply of fuel to a burner as long as a pilot light in juxtaposition to the burner is burning and as long as other means, such as a thermostat or other-condition responsive device, is operative to permit the same, and which syste'm is operable automatically to shut off the supply of fuel to the burner when the pilot light is extinguished and also when the other means, such as the thermostat or other condition responsive device, is operated to accomplish that result as, for example, where such other means is a thermostat, when the temperature adjacent the same reaches a predetermined maximum, or where such other means is some other form of condition responsive device, upon some other abnormal, defective, or insufficient functioning or non-functioning of the apparatus.

It is a further and more specific object of the invention to provide an improved safety shutoff system characterized by the combination with a diaphragm or other equivalent valve in the fuel supply pipe leading to the main burner, of a vent or bleed tube for venting said valve, a fuel supply pipe adapted to receive fuel from said vent or bleed tube and leading to a normal pilot burner in juxtaposition to the main burner, a second fuel supply pipe also adapted to receive fuel from said vent or bleed tube and leading to a second pilot burner in juxtaposition to the normal pilot burner, means responsive to the heat of either or both of the pilot burners and operative to shut off the supply of fuel to both pilot burners when the pilot lights go out, whereupon there is a building up of pressure at the diaphragm or equivalent valve with an accompanying operation of said valve to closed position; the

thermostatic or other responsive device, when acted upon by any outside influence, operates independently to shut off the supply of fuel to said second pilot burner with an accompanying building up of pressure at thev diaphragm or equivalent valve, thereby causing said valve to close.

Another object of the invention is to provide a thermoelectric safety shutoff system embodying the features herein disclosed.

Another object of the invention is to use the bleed fuel of constant and sufficient quantity and pressure from the diaphragm or equivalent valve in the fuel supply pipe leadingtojthe burner as the pilotburner fueL. I Another object is to provide'a system in winch a 100% shutoff may be secured; also a system in which the pilot flame responsive means comprises an electromagnetic valve and a thermocouple placed in position to be heated by the pilot light or lights and so located that it may be energized by the flames from either or both of the pilot burners and connected incircuit with the electromagnet, and a system of the character described having reset m eans for resetting the electromagnetic valve and in which the diaphragm or equivalent valve in the fuel .supply pipe leading to the burner cannot open during the resetting operation] I 1 Another object is to provide a system in which the reset means is operative "to establish a flow of fuel to the normal pilot burner and inwhich means is provided to interrupt or shut oil' the flow of fuel to the other pilot burner'during the resetting operation.

Another object of the invention is/to provide a safety shutoff system of the class described in which simple typesof thermostatsor other condition responsive device's, orfsmall "electric valves or the like, may be employed to control the action of the diaphragmyalve.

Another object is to provide a diaphragm valve which will fail'safe or operate to closed position if the diaphragm breaks.

Further features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings, in which: j

Figure 1 is a more or less schematic view showing a thermoelectric safety shutoif system embodying the present invention; 1, I v p Figure 2 is a vertical section through the dia-' phragm valve of the system shown in Figure 1;

Figure 3'is an axial section'through the electromagnetic valve of the system shown in Figure 1;

Figure 4 is a section through thethermostatic valve of the system shown in Figure l; and, Figure 5 is a section through the pilot burner structure. The invention can be embodied in a wide variety of forms for use with a wide variety of devices, but for purposes of illustration the invention has been shown more orless schematically as embodied in a manner automatically to close a valve in a fuel supply pipe leading to a burner when the pilot light for the 'burner'goes "out and also when a thermostat is operated to accomplish that result.

In Figure l of the drawings, the burner i is any suitable or preferred main burner, such as the burner of a room or space heater, water heater, floor furnace, or any other burner. A fuel supply pipe ll leads to the burner ID for the delivery of gaseous or other fuel thereto through the mixing chamber II, and a suitable valve, such, for example, as a diaphragm valve i2, is positioned in the pipe H.

The diaphragm valve l2 has a partition I3 dividing the interior thereof into an inlet chamber l4 and an outlet chamber [5. Formed in the partition I3 is a valve opening it having a valve seat I! formed about the upper end thereof. A valve casing part I8 is suitably secured to the main valve casing part, and clamped in place marginally by the casing part i8 is the flexible diaphragm l9. The diaphragm l9 divides the space between the valve casing part l8 and a second partition on the main valve body into an inner diaphragm chamber 22 and an outer diaphragm chamber 23. The partition 20 is shown as formed separate from the main valve body to facilitate mounting the valve 28 and its valve stem in place. This may vary.

The inlet chamber H of the valve communithe interior of the inner diaphragm chamber 22 so as to subject the inner side of the diaphragm I! to the pressure of the fuel in the fuel supply pipe II. The diaphragm l8 carries at the center thereof the valve stem 26 which has reciprocatory movement in the partition 20. The valve member 28, shown as of disk-like form, is carried by the inner end of the stem 28 and is adapted to seat upon the valve seat ll to shut off the flow of fue1 to the burner H). The diaphragm i9 is shown as provided with weights 38 clamped in place upon the stem 28 for actuating the valve member 28 to closed position, as shown in Figure 2, when pressure is allowed to build up in the outer diaphragm chamber 23 by the closing of one or both of the vents or bleed tubes, as will hereinafter appear. The diaphragm. valve is of a character to fail safe-that is, the weights 38 will operate the valve member 28 to closed position to shut off the flow of fuel to the burner [0 if the diaphragm breaks.

The valve stem 28 has a diametrical orifice which opens from the inlet chamber |4 into an Orifice 3B which extends axially through the valve stem 25 and opens at the outer end of the valve stem into the outer diaphragm chamber 23.

A pipe or tube 88 leads from the outer diaphragm chamber 23 to the inlet 38 of the electromagnetic valve designated in its entirety at 40.

The particular electromagnetic valve selected for illustration comprises a valve body 4| having, in addition to the inlet 38, a pair of

outlets

42 and 43.

A magnet mounting cup 44 of Bakelite" or any other suitable or preferred insulating material is mounted upon the outer end of the valve body 4| and closes the outer end of the bore 45. The cup 44 has, at its inner end, an integral extension which fits into the counterbore 48, and the cup 44 may be fastened in place by screws, or in any other suitable or preferred manner, preferably with a washer 41 between the cup and the valve body.

The magnet housing is in the form of an outwardly opening metal cup 48 mounted upon the mounting cup 44, for example by pressed fit engagement of its outer open end in the mounting cup at 48. The magnet cup 48 is reduced at its inner end at 58, and the armature housing, which is also in the form of an outwardly opening metal cup 5|, is mounted on the cup 48, for example by pressed fit engagement of its outer open end telescopically over the reduced inner end of the cup 48. The inner end of the cup 5| is preferably reduced as shown.

The electromagnet comprises a generally U- shaped magnet frame 54 positioned within the cup 48 with its legs extending through openings in the inner end of the cup 48 and presenting pole ends within the armature cup 5|. The form of the magnet frame may be varied and variations in the other parts of the apparatus are also contemplated within the scope of the present invention. The particular magnet frame 54 selected for illustration has a threaded stud 55 integral therewith, or welded or otherwise joined thereto. This stud 55 extends into an opening or recess 56 in the mounting cup 44 and has threaded engagement with a nut 58 for clamping the magnet frame 54 rigidly and, at the same time, removably in place. The nut 58 has a kerf for engagement by a screw driver or other suitable tool, and a sealing washer 59 may be provided between the nut 58 and the inner end of the recess 56.

Fixed in the mounting cup 44, as, for example, by molding the insulating material of the cup thereto and extending endwise from the cup 44, are a pair of spaced metallic terminal connectors 60 and BI having aligned openings 82. The terminal connectors 60 and ii are split outwardly of the openings 62, and the split portions are adapted to be clamped together by screws 64.

The magnet coil 66 surrounds the legs of the magnet frame 54, and the leads or end of this coil have their bared ends connected to the terminals 60 and GI in a manner to have good conducting contact therewith, as, for example, at 68 and 69. The coil 68 is preferably covered with insulation between the bared ends. If desired, additional insulation may be provided between the turns of the coil and the legs of the magnet frame and between the inner end of the cup 48 and the adjacent end of the coil.

The armature H is disposed in\ the armature cup 5| and is adapted to be held in attracted position against the pole ends of the magnet frame 54 when the electromagnet is energized. as will presently appear. The armature ll isof disc-like form and is secured to the outer end of a reciprocatory valve stem 12. The attachment of the armature II to the valve stem 12 may be sufficiently loose orotherwise of a character to permitself-accommodation of the armature to the pole ends of the magnet frame by a generally universal movement of the armature upon the'outer nd of the valve stem. The stem 12 is disposed generally concentrically of the armature housing 5| and extends inwardly for reciprocatory movement through an opening 18 in the inner end of the housing 5|.

The valve member 15 is fixed by a pin 18 upon the inner end of the valve stem", preferably for some relative movement thereon, so as to.

have self-accommodating seating engagement with the cooperating valve seat 18 at the outer end of the valve seat member 18. Packing '88 of felt or other suitable or preferred material is interposed between the bottom of the armature housing 5| and a, metal valve spring seating dis]; 82. The valve spring 83 is in the form of a coiled spring interposed between the valve member 15 and th spring seating disk 82 and centered, if desired, at opposite ends about the integral hub-like portions on thevalve member I and valve seating disk 82. The spring 83 resiliently moves the armature II to retracted position and the valve member I5 to closed position seating upon th valve seat I8 to shut off the flow of fuel to the

outlets

42 and 43 when the electromagnet is deenergized.

The disk 82 seats inwardly upon a shoulder in the bore 45, and the action of the spring 83 tends to compress the packing 80 and maintain same in sealing engagement with the bore 45 and with the valve stem I2, thus tending to seal the interior of the armature housing 5| from the gaseous or other fuel which passes through the valve body and to seal the valve body against the escape of fuel out around the magnet mounting cup and armature housing assembly. The deviceis further sealed against the escape of fuel by the washer 41.

A reset stem 88 extends through the inner end of the valv body 4I. This reset stem is mounted coaxial with the valve 15 and for reciprocatory movement. The stem 88 is provided at its outer end wtih a reset stem knob or button 89.

Fixed upon the stem 88 for reciprocatory movement therewith is a reset member 90 which has abutting engagement with a spring disk 92. The spring disk 92 is slidable in the cooperating cylinder part of the valve housing and constitutes a reset guide in the resetting operation. A spring 95, shown as of coiled form, is-interposed between this disk 92 and the valve seat member I9. A fuel flow interrupter spring 98 is interposed between the spring disk 92 and a flow interrupter disk valve 98. A retainer is provided at 99 for limiting inward movement of 'the disk valve 98 relative to the reset stem 88.

The disk valve 98 is adapted to seat upon the valve seat I00 at the adjacent end of the valve seat member I9 to shut off or interrupt the fiow of fuel to the outlet 43 .during the resettting operation and until the valve member 15 is held in open position by the thermoelectric current and the reset stem 88 is released. The reset member 88 has a tapered or generally conical portion which, under the action of the spring means, is held seated against a cooperating annular shoulder or seat on the valve body to seal the opening through which the reset stem 88 extends when the reset stem is positioned as shown in Figure 3.

The pilot burner means H2 comprises two pilot burners H8 and H8, the body portion of which is cast or formed integrally as shown in Figure 5. The pilot burner H8 constitutes the normal pilot burner. The side or pilot burner part H8 is mounted injuxtaposition to the main burner I0 and remains lighted in themanner presently to appear for the purpose of lighting the main burner.

When the valve member 15 is open, fuel is supplied through the outlet 42 of the electromagnetic valve 40 and connected pipe or tube ill to the normal pilot burner H8. Also, when the valve member I5 and flow interrupter disk valve 98 are open as shown in Figure 3, fuel is supplied through the other outlet 43 of the electromagnetic valve and a connected pipe or tube H4 to the other pilot burner. The flow of fuel through the tube H4 is controlled by a condition responsive device shown in the form of a thermostatic valve HIS.

It is to be understood that other condition responsive devices operated by contemplated within the scope of the broader aspects of the present invention. i

It will be noted that the outlet 42 opens out through the valve seat member I9 and the body of the electromagnetic valve outwardly of the valve seat I00 and between this valve seat I00 and the valve seat I8 at the outer end of the valve seat member I9. Thus, fuel passes out through the outlet 42 as long as the valve member I5 is open, and as long as the valve member I5 and fiow interrupter disk I00 are both open, fuel passes out through the outlet 43. The seating of th flow interrupter disk 98 upon the valve seat I00 during the resetting operation shuts off the fiow through the outlet 43 without shutting off the flow through the outlet 42.

The integrally cast body portion of the two pilot burners H8 and H8 has a recess H9 into which the fuel from the pipe H0 is delivered through an orifice I20; also a second recess I2I into which the fuel from the pipe H4 is adapted to be delivered through an orifice I22. The recess H9 has air inlet openings I23, and the mixture of air and fuel at the pilot burner H8 passes through a Venturi opening I24 to the pilot tip III from which it is discharged through an axial port I25 and a lateral port I26 to maintain, when ignited, the pilot flames indicated at I21 ings I30, and the mixture of air and fuel at the pilot burner part I I8 passes through a Venturi opening I32 to the pilot tip H5 from which it is discharged through an axial port I33 and a lateral port I34 to maintain, when ignited, the pilot flames indicated at I35 and I38.

The orifice 35 at the diaphragm valve is larger than the normal pilot burner orifice I20. The area of the orifice I20 plus the area of the second pilot burner orifice I22 is equal to, or larger than, the area of the orifice 36, so that when the valve member I5 and the valve I8I (Figure 4) are open, the gas or other fuel will bleed off from the outer diaphragm chamber 23 as fast, or faster than the inflow of gas into the chamber 23 through the orifice 36. In operation, the pilot burner H8 is ignited from the pilot burner H8, and vice versa. The orifice I22 is preferably larger than the orifice I20.

The differences in area between the orifice 36 and the orifice I20 is such that when the' pilot burner H8 is operating normally and correctly there will not be sufficient fuel bleeding from the outer diaphragm chamber 23 through the pipe H0 to allow the pressure of the fuel in the pipe II to open the diaphragm valve. The combined areas of the orifices I20 and I22 is sufficient to pass enough fuel so as to allow the fuel to bleed from the outer diaphragm chamber 23 fast enough to permit the diaphragm valve to be opened and held open bythe pressure of the fuel in the pipe II.

While any other suitable or preferred form of thermocouple and lead connection may be employed within the scope of the broader aspects of the present invention, the particular thermocouple and lead connection shown in the drawings are of the general character disclosed and claimed in Oscar J. Leins Patent No. 2,126.564. granted August 9, 1938. The thermocouple. designated in its entirety at I40, comprises an outer tubular metallic thermocouple member MI and an inner metallic thermocouple member I42 disposed within the outer thermocouple member and joined at one end to the outer thermocouple member to form the thermal junction I43 which is positioned to be heated by the pilot flames I28 and I36.

An inner lead conductor I44 is joined to the inner thermocouple member to form an internal thermal junction I45, and an outer tubular lead conductor I46 is connected to the outer tubular thermocouple member-for example, through a sleeve I41-to form a third thermal junction I48. The outer lead conductor and outerv tubular thermocouple member enclose the inner lead conductor and inner thermocouple member. The inner lead conductor I44 is insulated from the outer lead conductor I48, for example, by a wrapping of insulation on the inner lead conductor.

The thermocouple is supported between the pilot burners H8 and H8 by the cross part integrally connecting the same and in position to be energized by the flames from either or both of the ilot burners. The pilot tips III and II may be mounted detachably as shown, or otherwise, on the respective pilot burners. A's one suitable manner of supporting the thermocouple, the sleeve I41 of the thermocouple has an enlarged portion at I50 which seats at I5I on the cross part integrally connecting the pilot burners. A nut I52 has threaded engagement with a boss on the part connecting the pilot burners and cooperates with the enlarged portion I50 to clamp the thermocouple removably in place.

The pilot burner tips are developed to produce satisfactory ignition characteristics for each particular installation.

The inner and outer lead conductors are preferably of a character that will permit bending as desired to permit disposing the thermocouple in any desired position. At the end opposite the end at which the thermocouple is disposed the inner lead conductor I44 extends from the outer lead conductor I48 and has a metallic terminal sleeve I80 fixed thereon in good conductive contact therewith and spaced from the end of the outer lead conductor I56. An insulating sleeve I62 is interposed between the terminal sleeve I and the adjacent end of the outer lead conductor I46.

The thermocouple is connected to the terminals 60 and 6| of the electromagnetic valve by slipping the terminal end of the thermocouple lead means through the opening 62 in the terminal H and into the opening 62 in the other couple leads from the terminals and 6|.

For purposes of illustration, the invention is shown in connection with a water heater, and the thermostatic valve II6 for controlling the flow of fuel through the pilot supply tube H4 is shown as comprising a rod and tube form of thermostat. As already pointed out, however, other forms of thermostats and other forms of condition responsive devices for controlling the flow of fuelthrough the vent or bleed tube II4 are contemplated.

The thermostatic valve H6 selected for illustration comprises a body or valve casing I15 having an inlet I16 connected by a part of the pipe II4 to receive fuel from the outlet 43 of the electromagnetic valve 40 and an outlet I11 connected by the other part of the pipe II4 to deliver the fuel to the tip II5 of the pilot burner H8. The inlet I18 opens into an inlet chamber I18 in the casing I15, and the outlet I11 leads from an outlet chamber I19. A valve opening I80 provides for communication between the inlet chamber I18 and the outlet chamber I18, and this valve opening is controlled by a valve I8 I. A spring I82, interposed between the valve I8I and a removable cap I83, presses the valve I8I toward the seat I84.

The valve casing I15 is externally threaded at I to be mounted in the shell or wall I86 of a water heater as shown, for example, in Figure l. The tube I81 extends-into the tank I86 for contact with the water therein. The rod I88 is disposed axially within the tube I81, with its inner end cooperating with a plug or cap I08 closing the inner end of the tube I81 The outer end of the rod I88 is pointed, and this pointed outer end engages an arm I80 which is disposed within the valve casing I15 and which is fulcrumed at one end upon the pointed inner end of an adjusting screw I9I. The screw I9I is adjustable in the casing I15 for the purpose of adjusting the temperature at which the thermostat is operable to close the valve I8I. The opposite end of the arm I90 cooperates with the valve stem I92 so that until the temperature at which the valve I8I is to close is reached, the rod I88, by its cooperation with the arm I90, holds the valve I8I against the action of the spring I82.

The tube I81 is composed of a thermally responsive metal which has a coeflicient of expansion different from the coefficient of expansion of the metal rod I80. As a result, when the temperature is reached at which the valve I8I is to close, the expansion of the tube I81 releases the action of the rod I88 on the arm I90 sufficiently to permit the spring I82 to move the valve I8I to closed position, thereby shutting off the flow of fuel through the vent or bleed tube I I4 to the tip I I5 of the pilot burner II8.

To start the operation of the system, the following sequence is followed:

The reset stem 88 is pressed inwardly to actuate the valve member 15 to open position and the armature H to attracted position in contact with the pole faces of the magnet frame 54. This allows the fuel to flow through the outlet 42 and pilot line IIO to the normal pilot burner 8' where the same is ignited. The stem 88 is held in depressed position until the flame I28 has heated the thermocouple sufficiently to energize the magnet 54 so that it will hold the armature 1I attracted thereto and, thereby, the valve member 15 in open position. The flow interrupter disk 98 seats upon the seat I00 to shut off the flow of fuel to the outlet 43 as long as the stem 80 is pressed inwardly.

When the magnet is energized sufliciently to hold the armature H in attracted position and the valve member 15 in open position, the reset stem 88 is released, thus allowing the flow interrupter disk to return to open or normal operating position. Fuel then flows out through the outlet 43 and pilot line II4 to the thermostatically controlled valve at II6. Assuming that the valve at I I8 is open, this fuel is delivered to the tip I I5 of the pilot burner IIB through the pilot line II4 where it is ignited by the pilot burner H8. If, on the other hand, the pilot burneris not lighted to produce the thermoelectric current for holding the armature in attracted position and the valve I5 open, the armature II will be actuated to retracted position and. the valve 15 to closed position upon release of the reset stem 88.

With the thermostatic or other condition responsive valve I8I in the vent or bleed tube I I4 open, both of the vents or bleed tubes operate to vent or relieve the pressure of the fuel delivered to the outer side of the diaphragm through the orifice 36 fast enough to permit the diaphragm valve to be opened and held open by the pressure of the fuel in the pipe II. The orifice I20 is smaller than the orifice 36 and is designed definitely to prevent fuel from bleeding from the outer diaphragm chamber 23 in quantity sufiicient to enable the diaphragm valve to open, whereas the orifice I22 may or may not be large enough to allow the diaphragm valve to open. The orifice 36 at the diaphragm valve I2 being larger than the orifice at I20, it will be obvious that when the flow or escape of fuel through the vent or bleed tube H4 is shut off, the delivery of fuel into the outer diaphragm chamber 23 through the orifice 36 will cause pressure to build up in the outer diaphragm chamber This results in overcoming the pressure of the fuel in the main fuel supply pipe on the inner side of the diaphragm I9 sufficiently to permit actuation of the valve 28 to closed position, for example, by the weights 30, to shut off the supply of fuel to the main burner I0.

In the illustrated embodiment of the invention, when the temperature of the water in the tanl:- ififi reaches the temperature at which it is desired automatically to shut off the supply of fuel to the main burner ID, the tube and rod thermostat I81 and I88 releases the thermostatic valve I8I, which valve' thereupon is closed by the spring I82, shutting off the supply of fuel through the vent or bleed tube H4 and thereby the supply of fuel to the pilot tip H5. The orifice I20 for the bleed tube III) being smaller than the orifice 36, pressure builds up in the outer diaphragm chamber 23 and the diaphragm valve 28 is actuated to closed position to shut off the supply of fuel to the main burner Ill. The supply of fuel, however, continues through the pipe 38, inlet 39 of the electromagnetic valve 40, outlet 42, and tube III], to the pilot tip III to maintain the pilot flames at I21 and I28 so that when the temperature drops or the other condition to which the valve IBI is subjected is corrected, the flow of fuel thereupon again set up to the pilot jet I I5 through the tube I I4 will be ignited to provide the multi-frame pilot.

If, on the other hand, both of the pilot burners are extinguished so that the thermal junction M3 is no longer heated sufficiently to set up the thermoelectric current for energizing the electromagnet to hold the armature 'II attracted and the valve 15 open, the armature 'II is released and the spring 83 moves the armature to retracted position and the electromagnetic valve I5 to closed position, shutting off the flow of fuel not only through the tube I III to the pilot tip II I, but also the flow of fuel through the tube I I4 to the pilot tip II5. As a result, pressure builds up in the outer diaphragm chamber 23, and the diaphragm valve 28 is closed to shut off the supply of fuel to the main burner.

From the foregoing description, it will be apparent that the present invention provides for the use of bleed gas or fuel from the diaphragm valve as the pilot burner fuel, that it provides a 100% shutoff, that the diaphragm valve cannot open during the resetting operation, that the system will fail safe if the diaphragm breaks, and that simple types of thermostats or small electric valves or other suitable control devices may be employed to control the action of the diaphragm valve.

I do not intend-to be limited to the precise details shown or described.

I claim:

1. In combination, a main burner, a fuel supply pipe leading to said burner, a valve in said pipe, said valve having a diaphragm subject on one side to the pressure of the fuel in said pipe and having a diaphragm chamber on the other side thereof, means for constantly bleeding fuel into said diaphragm chamber from the fuel supply pipe anterior of said valve, a pair of vents for venting said diaphragm chamber, said valve being opened and held open by the pressure of the fuel in said pipe on said diaphragm when both of said vents are open, and means operable to open and close one of said vents independently of the other vent, said other vent being of a size to prevent, when said other vent only is open, venting said diaphragm chamber sufficiently to permit said diaphragm valve to be opened and held open by the pressure of the fuel in said pipe.

. 2. In combination, a main burner, a fuel supply pipe leading to said burner, a valve in said pipe, said valve having a diaphragm subject on one side to the pressure of the fuel in said pipe and having a diaphragm chamber on the other side thereof, means for constantly bleeding fuel into said diaphragm chamber from the fuel supply pipe anterior of said valve, a pair of vents for venting said diaphragm chamber, said valve being opened and held open by the pressure of the fuel'in said pipe on said-diaphragm when both of said vents are open, means operable to open and close one of said vents independently of the other vent, and a second means operable to open and close said other. vent, said other vent being of a size to prevent, when said other vent only is open, venting said diaphragm chamber sufiiciently to permit said diaphragm valve to be opened and held open by the pressure of the fuel in said pipe, 7

3. In combination, a main burner, a fuel supply pipe leading to said burner, a valve in said pipe, said valve having a diaphragm subject on one side to the pressure of the fuel in said pipe and having a diaphragm chamber on the other side thereof, means for constantly bleeding fuel into said diaphragm chamber from the fuel supply pipe anterior of said valve, a pair of vents for venting said diaphragm chamber, said valve being opened and held open by the pressure of the fuel in said pipe on said diaphragm when both of said vents are open, means operable to open and close one of said vents'independently of the other vent, and second means operable to open and close both of said vents, said other vent being of a size to prevent, when said other vent only is open, venting said diaphragm chamber suiliciently to permit said diaphragm valve to be opened and held open by the pressure of the fuel in said pipe.

4. In combination, a main burner, a fuel supply pipe leading to said burner, a main valve in said pipe, said valve having a diaphragm subject on one side to the pressure of the fuel in said pipe and having a diaphragm chamber on the other side thereof, means for constantly bleeding fuel into said diaphragm chamber'from the fuel supply pipe anterior of said valve, a pair of bleed tubes for venting said diaphragm chamber, said valve being opened and maintained open by the pressure of the fuel in said pipe on said dia- 'phragm only when both of said bleed tubes are operating to vent said valve, said bleed tubes constituting supply tubes for pilot lights at least one of which is located in juxtaposition to said burner, and condition responsive means having a safety position for shutting off the flow of fuel through one of said bleed tubes and an operating position for the flow of fuel through said tube, the other tube having a'vent'of a size to prevent, when said other. tub only is open, venting said diaphragm chamber sufficiently to permit said diaphragm valve to be opened and held open by the pressure of the fuel in said pipe.

, a In combination, a main burner, a fuel supply pipe leading to said burner, a valve in said pipe, said valve having a diaphragm subject on one side to the pressure of the fuel in said pipe and havinga diaphragm chamber on the other side thereof, means for constantly bleeding'fuel into said diaphragm chamber from the fuel supply ,pipe anterior of said valve, a pair of bleed tubes for venting saiddiaphragm chamber, said 'valve being opened and maintained open by the pressure 'of the fuel in said pipe on said diaphragm' only when both of said bleed tubes are operating to vent said valve, said bleed tubes constituting supply'tubes for pilot lights at least one of which is located in juxtaposition to said burner, condition responsive means having a safety position for shutting off the flow of fuel through one of said bleed tubes and an operating position for the flow of fuel through said one tube, theother tube having a vent of a sizeto prevent, when saidone tube is closed and said other tube'is open, venting said diaphragm chamber sumciently to permit said diaphragm valve to be opened and held open by the pressure of the fuel in said pipe, and means responsive to the heat of the pilot lights and operable to shut ofl the flow of fuel through both of said bleed tubes when the pilot lights go out; I

, '6. In a safety shutoifsystem of'the class described, a main burner, a fuel supply pipe lead- 'ing to said burner, a diaphragm valve in said pipe, said valve having a diaphragm' subject on one side to the pressure of the fuel in said pipe andhaving a diaphragm chamber on the other side thereof, means forjconstantly bleeding fuel intoeaid diaphragm chamber from the fuel supply pipe anterior of said valve, a vent tube for venting said diaphragm chamber, a fuelsupply pipe adapted to receive fuel from said tube and leading to a normal pilot burner in juxtaposition to lthe main burner, a second fuel supply pipe also adapted to receive fuel from said tube and leadingto a second pilot burner in juxtaposition to the normal pilot burner, means responsive to the heat. of the pilot burner "and operative-to shut off thesupply of fuel to both pilot burners when said pilot burners go out, whereupon there is a building up of pressure in the diaphragm chamber with an accompanying operation of said valve to closed position, and a. condition respon sive device operative to shut off the supply of fuel to said second pilot burnerwith an 'accom panying building up of pressure in the diaphragm chamber and operation of said valve to closed position, the'normal pilot burner affording a vent for said diaphragm chamber of a size to prevent, when said'vent is open, venting said diaphragm chamber sufficiently to permit said diaphragm valve to be opened and held open by the'pres sure of the fuel in said pipe.

'7. In combination, a main burner, a fuel supply pipe leading-to said burner, a valve in said pipe, said valve having a diaphragm subject on one side to the pressure of the fuel in said pipe and having a. diaphragm chamberon the other side thereof, means forconstantly bleeding fuel into said diaphragm chamber from the fuel supply pipe anterior of said valve, a pair of vents for venting said diaphragm chamber, two pilot lights one receiving fuel from one of-said vents and the other receiving fuel from the other of said vents, and thermoresponsive means for opening and closing one of said vents, said valve being opened and held 'open by the pressure of the fuel in said pipe only when bothi of said vents are open. i

8. In combination, a main burner, a fuel supply pipe leading to said burner, a valve in said pipe, said valve havinga'diaphragm subject on one side 'to the pressure of the fuel in said pipe and having a diaphragm chamber on the other side thereof, means for constantily bleeding fuel into said diaphragm chamber from th'e fuel supply pipe anterior of said valve, a pair of vents-for venting said diaph ragm chamber, said valve being opened and held open by the pressure of the fuel in said pipeonly when both of said vents are open, means for losing one of said vents, and means for delivering fuel from said fuel supply pipe through the other vent-when said first men- ,tioned'vent is closed and when'the valve in said fuel supply pipe is closed.

9. In combination, a main burner, a fuel supply pipe lead'ingto said burner, a valve in said pipe, said valve having-a diaphragm subject on one side to the'pressure of the fuel in said pipe'and having a diaphragm chamber on the other side thereofimeans for constantly bleeding fuel into said diaphragm chamber from the fuel supply pipe anterior of said valve, a pair of vents for venting said diaphragm chamber, said valve' being opened and held open by the pressure of the fuel in said pipe on said diaphragm when both of said'vents are open, a valve member operable to open and close, one of said vents independently of the other vent, a second valve member operableto open and close both of said vents, a thermocouple positioned to'be heated by a flame supplied with 'fuel by the'other vent, an electromagnet connected in circuit with said thermocouple, and an armature for said electromagnet, said second valve member being heldin'open I position when the armature is held attracted to saidelectromagnct and operable to closed position to closeboth'of said vents when the armature is retracted.

STANLEY S. GUELSON.