US2193697A - Safety gas-expulsion device for furnaces - Google Patents

Description

March 12, 1940; 5 s ROBERTS 2,193,697

SAFETY GAS-EXPULSION DEVICE FOR FURNACES Filed July 15, 1938 lyweizlor:

Patented Mar. 12, 1940 I UNITED STATES SAFETY GAS-EXPULSION DEVICE FOR FURNACES Samuel s. Roberts, Pittsburgh, Pa.

Application July 15, 1938, Serial No. 219,460

7 Claims.

This invention relates to furnaces and, particularly, to an automatic safety gas-expulsion device therefor.

'In furnaces, especially of the type used for heating metallic articles, having a forced draft or pressure air burners for firing combustible gaseous fuels, the gases oftentimes accidentally seep into the forced draft blast mains, the furnace, or the combustion chamber during the time the forced draft is shut oflf'and the furnace is not in operation, and explode when the furnace is again put into operation, resulting in damage to the' furnace and a hazard to human life. It is therefore desirable that any waste gases, or gases that may have le'aked'into the furnace and its associated parts,.be expelled'therefrom while it not in operation or, at least, before it is again fired and put into operation.

Accordingto the present invention, there is conveniently positioned, close to the furnace in .the forced draft system, a gas-expulsion device which automatically goes into operation to expel the gases from the furnace and its associated parts whenever the forced draft is shut off and the furnace is not operating.

It is an object of the present invention to provide an improved gas-expulsion device which will automatically expel any gases from the furnace when the furnace is not in operation.

It is another object of the invention to provide an improved automatic gas-expulsion device which is simple and inexpensive in its, construction and operation and one which is dependable and will insure'the expulsion of any gases from the furnace when not in operation.

It is a still further object of the invention to provide a gas-expulsion device which is adapted to be closed and rendered inoperative bythe action of the forced draft when the furnace is in operation, and permitted to open and be in operation when the forced draft is shut off and the furnace is not in operation.

Various other objects and advantages of this invention will be more apparent in the course of the following specification and will be particu larly pointed out in the appended claims.

In theaccompanying drawing, there is shown,

for the purpose of illustration, one embodiment whichmy invention may assume in practice.-

In the drawing: Figure 1 is an elevation showing the location of the improved safety gas expulsion device -of my invention relative to the blower and furnace;

Figure 2 is an enlarged elevation, partly in section, of my improved safety gas expulsion de-s vice; and,

Figure 3 is a section taken on the line III- -III on the end of a shaft of a motort, which is suitably arranged on a platform 1 above the blast or forced draft pipe or conduit of a furnace l. The housing 4 of the fan is connected to the blast or forced draft pipe, preferably bymeans of an elbow connection 9 or any other suitable connecting means. The metallic cylinder 2 preferably has a reduced upper end on which there is mounted a smaller cylinder [0 having a hood. I! arranged on the top and spaced from the end thereof.

There is arranged in the cylinder 2 and centrally thereof, a valve comprising a movable spherical member" l3, preferably a spun brass ball having a smaller outer diameter than the inner diameter of the cylinder and a cup-like seat member, also preferably of spun brass, attached to the inside walls of the cylinder and having an opening therein with which the ball is adapted to cooperate. The ball I! has arranged diametrically therethrough and secured'thereto an upwardly extending guide tube l5, preferably of brass, and-on the end thereof there is arranged an upwardly-extending rod l6 which is adapted to extend upwardly through an opening in the hood l2. There is arranged below the ball l3, and secured to the inner walls of the cylinder 2, a wire basket I! which is adapted to support the brass ball it. There is also ar ranged, just below the ball, an actuating member l8, preferably a forked member, having one end slidably positioned in the lower end of thetube l5 and the forked end thereof pivotally connected to the end of an actuating switch lever l9 extending through a vertically extending slot inthe side of the cylinder 2 to a switch. 20, preferably of a mercoid type. There is arranged on, the forked member I! a coil compression spring 2| which is adapted to cooperate between the forked portion of the member II and the bottom of the ball I: to cushion the seating 01 the same 'in its downward travel.

It will be understood that the weight of the ball and the parts connected therewith forces the lever ll downwardly, closing the switch 20 to actuate the motor I and the fan 5. There is arranged within the cylinder 2 a tension coil spring 22 connected to the switch lever l9 and to the inner wall of the cylinder 2 which is adapted to force the switch lever l9 upwardly to open the switch when the ball l3 and interconnected parts are in their top-most position, with the ball seated in the member I. There is associated with the lever I9, next to the slot in the side of the cylinder 2 through which the lever l8 extends, a sliding door 23 which is adapted to be moved by the switch lever in its movement to keep the slot in the cylinder closed at all times so as to prevent the escape of the-air therethrough.

The guide tube It is, of course, arranged centrally of the cylinders 2 and I0 and there is positioned in the cylinder l0 guide means, such as preferably a short piece of brass tubing 24 around 'the tube I5, for guiding the vertical movement of. the tube I! and ball l3. The rod I6 is adapted to extend through the hood I2 so as to indicate, at all times, the position of the ball II in the cylinder 2.

It will be understood that so long as the air pressure in the blast or forced draft pipe of the furnace is normal, as it is supposed to be during the firing thereof, the device is inactive; but when the pressure in this pipe decreases below a fixed point or upon discontinuing the -forced draft,

that is, when the furnace is not being fired, the device becomes active automatically as follows:

The air pressure in the blast or forced draft pipe which is of a relatively higher pressure than that generated by the exhaust fan, lifts the ball "upwardly to seat it in the member H, closing the outlet through the cylinder to the atmosphere with the switch lever l9 beingmoved simultaneously in an upward direction, to open the switch 20, thereby stopping the motor 6 and exhaust fan 5. When the air pressure drops below a predetermined point, or the blast or forced draft is discontinued during the time the furnace is not in operation, the ball [3 drops, cushioning itself on the coil spring 2|, opening the blast pipe to the atmosphere and forcing the lever l9 downwardly to close the switch 20, thereby starting the motor 6 and the exhaust fan 5. The exhaust unit then automatically starts to remove any gases that may collect in the furnace or its associated connections through gas seepage that may occur through leaking burners or gas valves or any unburned gases that may have been left in the furnace when it was shut down,thereby preventing the building up of any explosive mixture in the furnace or the parts connected therewith. The exhaust gases are forced upwardly through the cylinder 2 through the wire basket and the spacebetween the sphericalmember or ball i3 and the inner wall of the cylinder into the atmos phere. It will be understood that the pressure in the forced draft pipe is great enough to raise and other forms may be devised within the scope of my invention, as defined in the appended claims.

'I claim:

1. In combination with a pipe or conduit for supplying a forced draft to furnaces and the like,

' apparatus including an exhaust fan connected to said forced draft pipe, a vertically disposed hollow cylindrical member open to the atmosphere attached to said fan and extending upwardly therefrom, a valve arranged in said cylindrical member intermediate the length thereof above member upwardly seating the same in the upper valve seat closing the cylindrical member when a forced draft is passing through the pipe, thereby opening the switch so as to prevent the errhaust fan from operating and permitting the spherical member to move downwardly due to the force of gravity, thereby closing the switch and setting the exhaust fan in operation to expel any gases that may collect in the furnace and the parts associated therewith therefrom into and through the cylindrical member and valve into the atmosphere when a forced draft is not passing through the pipe.

2. In combination with a pipe or conduit for supplying a forced draft to furnaces and the like, apparatus including a safety gas expulsion device consisting of a vertically arranged hollow cylinder open at its ends, a spherical member arranged in said cylinder, means for supporting and guiding said spherical member therein, a seating member arranged in the cylinder above said spherical member and with which it is adapted to cooperate, an exhaust fan positioned below said spherical member and communicating with said cylinder and said pipe, said spherical member adapted to be forced upwardly into said seating member to close the cylinder by the forced draft passing through the pipe, and means actuated by said spherical member to set said exhaust fan in operation when the spherical member is in its lowermost position and the cylinder is open and the forced draft is not passing therethrough, said exhaust fan expelling any gases from the furnace and the parts'associated therewith through said valve and cylinder.

3. In combination with a pipe or conduit for supplying a forced draft to a furnace, apparatus including an exhausting means connected to the forced draft pipe and in communication therewith so as to be effective when in operation to expel gases from the furnace and the parts as- 'sociated therewith, and means responsive to a predetermined drop in the pressure of the forced draft forautomatically setting said exhausting means in operation.

, 4. In combination with a pipe or conduit for supplying, a forced draft to furnaces and the like, apparatus including an exhausting means associated with said pipe for expelling gases from'the furnace and the parts associated therewith when the furnace and forced draft is not in operation, means controlled by the forced draft for controlling said exhausting means, said last mentioned means adapted to be actuated by the forced draft to control the exhausting means so as to make the same inoperative when a forced draft is passing through the pipe and adapted to control the exhausting means so as to make the same operative when a forced draft is not passing therethroughi 5. In combination with a pipe or conduit for supplying a forced draft to furnaces and the like, apparatus including a safety gas expulsion device 'havin'g'an exhaust fan associated therewith which is connected to said forced draft pipe,

means controlled by the forced draft for control-- ling said exhaust fan, said last mentioned means adapted to be actuated by the forced draft to make the exhaust fan inoperative when a forced draft is passing through the pipe and adapted to make the exhaust fan operative when a forced draft is not passing therethrough.

6. In combination with a, pipe or conduit for supplying a forced draft to furnaces and the like, apparatus including a safety gas-expulsion device consisting of an exhaust fan," a switch for controlling said exhaust fan and a valve for controlling said switch, said device being constructed and arranged so that the forced draft actuates motion so as to expel any gases that may have: collected in the furnace and the parts associated therewith therefrom.

7.. In combination .witha pipe or conduit for supplying a forced draft to'a furnace, apparatus including a normally inactive exhaust fan connected to the forced draft pipe and in communication therewith so .as to be effective when in operation to withdraw gases from the furnace and the parts associated therewith, an outlet duct associated with said fan, a valve interposed between the exit end of said outlet duct and said fan, a motor for driving said fan, and a switch for controlling said motor, said switch being actuated by the movement of said valve, said valve being normally closed when normal pressure is maintained in the forced draft pipe thereby maintaining the switch in an open position and the 1 fan inoperative and being arranged to close the switch so as to place the motor and fan in operation when the forced draft pressure in the pipe drops below, a predetermined point.

SAMUEL S. ROBERTS.

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