US2147568A - Gas shut-off means for mixing apparatus - Google Patents

Description

Feb. 14, 1939. BARBER I 2,147,568 V GAS SHUT'OFF MEANS FOR MIXING APPARATUS Filed April 3, 1937 lnventor (Ittomeg Patented Feb 14,1939 it V 2,147,553

UNITED STATES PATENT OFFICE face Combustion Corporation, Toledo, Ohio; a corporation of New York Application April 3, 1937, Serial No. 134,888

Claims. (01. 158-419) This invention relates to improvements in gas the gas flowing to the chamber I8 is low, usually mixing and proportioning apparatus of the type atmospheric pressure, the gas being drawn into disclosed in patent to Peters 1,574,107, dated the tube H by the entralning efiect oi the air February 23, 1926. In this type of apparatus, air flowing therethrough.

5 under pressure is caused to flow through aVenturi In the main gas supply pipe 2! is a governor 5 tube and gas is supplied to thetube at relatively comprising a balanced valve 22, a diaphragm low pressure which is usually atmospheric pres- 23 and a pipe 24 leading from the pipe I 9 to the sure, the gas being drawn into the tube by the underside of the diaphragm, the arrangement beentraining effect of the air flowing therethrough.. ing such that it the pressure in the pipe is ex- 10 The gas pressure is controlled by a governor comcoeds atmospheric pressure, the diaphragm will 10 prising avalve and a diaphragm, the arrangement be operated to move the valve 22 toward closed being such that as the entraining efiect of the air position. Ordinarily the diaphragm 23 will be flowing through the Venturi tube decreases, due arranged in a vertical plane and the valve 22 and to decrease in air flow, the diaphragm tends to its stem to move in a horizontal plane in order move the valve toward closed position (by reathat the weight of the parts shall not be a factor 16 son of the increase in pressure between the in determining the regulated pressure.

Venturi tube and the governor valve) to compen- Th apparatus th far d c ib d i t ,11 msate tor the lesser amount of gas required to t t a purposes t same as t shown in the form the desired mixture. Suppose now that aforesaid patent to Peters 1,574,107, 20 the all flow t0 the Venturi tube is entirely shut Under ordinary operating conditions the non- 2o of! or shut off to such degree-that the air passvalve side of the governor diaphragm 23 is ext ht Said tubetxerts I appreciable posed to the atmosphere as by a vent in the entraining effect on the gas: In such case it is diaphragm case. In the present instance it is desirable that the governor valve should be tightso exposed by way of passages 25 and 26, the Y 25 ly closed to prevent leakage of gas into the furpassage 25 being a small pipe and the passage 25 nace whereinto the burner discharges. However, 28 being part of a small Venturi tube whose disv since the pressure which must be relied on to charge end is open to the atmosphere, said pipe actuate the diaphragm to close the valve, when connecting with said tube at its restricted porthe air is shut off, is substantially atmospheric tions. Leading from the air conduit l5 at the up- 30 pressure, the valve, under ordinary operating stream side of the valve i! is a pipe 28 which 30 conditions, does not close tightly enough to preleads to the mouth of the Venturi tube 21. In vent leakage 01,8 8 past the valve and, therefore, this pipe 28 is a valve 29. If this valve 29 is into the furnace. open,'a ir will flow from the conduit l5 through Now, therefore, the object of the present inventhe small Venturi tube 21 and by its entraining tion is to provide simple and practical means for effect in flowing through said tube 21 will protightly closing the governor valve when the air duce a negative pressure on the adjacent (or nonflow to the Venturi tube is shut off. The way in valve) side of the diap 23 w he result which this object is accomplished will be fully that the diaphragm will move the valve 22 to explained in the detailed description taken in closed position. Under ordinary operating con.-

0 connection with the accompanying drawing ditions the valve 29 in the pipe 28 will be held 49 wherein the single figure is a diagrammatic view closed by 11168-118 including a diaphragm 30 con- 1 t preferred form 1 th i nti n, nected to the valve 29 and a pipe in leading from It) indicates a burner port in the wall ll of a. the air conduit l5 at the downstream side of the furnace which is not otherwise shown; l2 a valve H. The area of the d p ragm 30 is many burner nozzle positioned to discharge into said times greater than the area 0f the Valve 29 in 45 port; I! a mixture supply pipe delivering to the order that the pressure of the air in the conduit burner nozzle from the Venturi mixing tube l4; l5 t t downstream Side Of the VEZIVE H y iii a conduit for delivering air under pressure to reach a low value before the pressure in the air I the mouth l6 of the said tube for flow through conduit at the upstream side oi'tlie valve H can so the latter, and 'il a gate valve or the like for open the valve 28 and thereby permit air to flow 5o regulating the amount of air supplied to said tube. to the small Venturi tube 21 for the purpose of Surrounding the tube M at its restricted por causing the governor valve 22 to close. By way tion is a chamber iii to which the gas flows from of illustration, suppose that the air in the cona supply pipe IS, the tube having radial inlet duit i5 at the upstream side oi the valve ii is an ports 20 inits rmtricted portion. The pressure of one pound. 'Ihe relative oi the vaivc and the diaphragm 30 would then be so proportioned that a pressure of say one inch of water in the conduit I5 at the downstream side of the valve l1 would suflice to hold the valve 29 closed This is equivalent to saying that the valve H in the air conduit I 5 may be moved toward closed position to such degree that so long as the air pressure at the downstream side of the valve ll does not fall below'one inch of water, the valve 29 in the pipe 28 will remain closed and thereby permit the gas governor to function normally until such time as the valve I1 is practically closed.

As previously indicated the object of closing the governor valve 22 is to prevent the leakage of gas into the furnace when the supply of air to the Venturi mixing tube I4 is shut off or so nearly shut off as will amount to shutting oil the burner l2.

Although the air conduit valve IT has been shown as a manually operable valve, it will nevertheless be understood that it may be automatically controlled by temperature responsive means in the furnace. Such temperature responsive means will ordinarily cause the valve IT to be fully open or fully closed. The desirability of preventing the leakage of gas into the furnace when the valve IT is ciosedwill be readily appreciated by those skilled in the art.

The Venturi tube 21 associated with the gas governor will ordinarily be a relatively minute affair as compared with the Venturi mixing tube E4. The valve 29 will also be a relatively small affair comparable to a needle valve. It will, therefore, be understood that the various parts in the drawing are not necessarily shown in their proper proportion with respect to each other, since the view is intended to be diagrammatic only.

From the foregoing description-it will be readily appreciated that the present invention provides a relatively simple and practical way for insuring closing of the governor valve when the air supply to the Venturi mixing tube M is decreased to some definite value.

What I claim is:

1. In apparatus for producing and supplying a mixture of gases in substantially constant proportion and comprising a mixing tube, air and gas conduits delivering to said tube in such a way that the air in flowing through the tube tends to draw the gas into the tube, a valve in the gas conduit, a diaphragm exposed on one side to the pressure of the gas flowing to said tube and adapted to control the operation of said valve whereby to control the pressure of the gas flowing to said tube, and a shut-oil valve in the air conduit, the combination with said apparatus, or

means for automatically closing the gas conduit valve when the pressure difference across the air conduit valve exceeds a predetermined amount, said means comprising a suction-producing device ior decreasing the pressure on that side of the said diaphragm that is not exposed to the pressure of the gas flowing to said mixing tube, and another diaphragm exposed to the pressure prevailing in the air conduit at the down-stream side 01' the shut-off valve therein for controlling the operation of said suction-producing device.

2. In apparatus for producing and supplying a mixture of gases in substantially constant proportion and comprising a mixing tube, air and gas conduits delivering to said tube in such a way that the air in flowing through the tube tends to draw the gas into the tube, a valve in the gas conduit, a diaphragm exposed on one side to the pressure of the gas flowing to said tube and adapted to control the operation of said valve whereby to control the pressure of the gas flowing to said tube, and a shut-off valve in the air conduit, the combination with said apparatus, of means for automatically closing the gas conduit valve when the pressure of the air in the air conduit at the down-stream side of the said valve therein decreases to a predetermined amount, said means comprising a fluid-operated suction producing device for actuating said diaphragm, a

valve which when closed prevents operating fluid from flowing to said device, and a diaphragm coupled to the last mentioned valve and exposed on one side to the pressure prevailing at the downstream side of said air valve.

3. In firing apparatus comprising a burner to which air and gas are to be delivered, the combination of a pressure-air supply line and an air shut-off valve therein, a movable element which is held in one position by the air pressure at the discharge side of said valve when the latter is open and'which is held in another position by the air pressure at the intake side of said valve when the latter is closed, a gas supply line, a gas valve in said gas line which is normally open when the said air valve is open, and means controlled by said movable element for positively closing said gas valve when said air valve is moved to closed position.

1. In firing apparatus comprising a burner to which air and gas are to be delivered, the combination of a pressure-air supply line and an air shut-off valve therein, a gas supply line and a diaphragm-controlled gas valve therein, a device for producing suction at one side of said diaphragm whereby to close the gas valve whenever said suction device is actuated, and means responsive to the position ,of said air shut-oil valve for actuating said suction device Whenever said air shut-oil valve is closed.

5. In the combination specified in claim 3, said movable element comprising two interconnected pressure responsive members of different pressure area, the small area member being exposed tov the air pressure at the intake side of said air valve and the large area member being exposed to the air pressure at the discharge side of said air valve, whereby when the ratio of the pressure at the intake side of said air valve to the pressure at the discharge side of the same exceeds a predetermined value, said members will be moved as a unit.

HUGH B. BARBER.

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