US1298890A

US1298890A - Method and apparatus for the differential detection of combustible atmospheres.

Info

Publication number: US1298890A
Application number: US16572217A
Authority: US
Inventors: Thomas M Chance; Edwin M Chance
Original assignee: Individual
Current assignee: Individual
Priority date: 1917-05-01
Filing date: 1917-05-01
Publication date: 1919-04-01
Anticipated expiration: 1936-04-01

Description

T. M. & E. M CHANCE.

METHOD AND APPARATUS FOR THE DIFFERENTIAL [)FTECIIUN 0F C(WBUSTIBLE ATMOSPHERE-S.

APPLICATION FILED MAY i. WIT.

1,298,890., T lutvnl'wi Apr. 1, I919,

WITNESSES: INVENTORS:

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THOMAS M. CHANCE, OF WILKES-BARREL EDWIN M. CHAN CE, OlF PHILADELPHIA, PENNSYLVANIA.

METHOD AND APPARATUS FOR THE DIFFERENTIAL DETECTION OF COMBUSTIIBLE ATMOSPHERES.

Patented Apr. 1, 1919.

Application filed May 1, 1917. Serial No. 165,722.

To all whom it may concern:

Be it known that we, THOMAS M. CHANCE and EDWIN M. CHANCE, citizens of the United States, and residing, respectively, at \Vilkes-Barre and Philadelphia, in the State of Pennsylvania, have invented a certain new and Improved Method and Apparatus for the Differential Detection of Combustible Atmospheres, of which the following is a specification.

The object of our invention is to provide means whereby the presence of combustible gases in the atmosphere may be made known provement in method and apparatus disin which one comclosed in said application,

detected bustible gas may be differentially with reference to another.

To attain this end We provide a source of heat and an oxidizing material, both of said elements being in operative relation to temperature responsive elements operatively connected to aural or visual signal devices.

The drawing represents a vertical crosssection illustrating diagrammatically the general association of elements necessary to the operation of our invention.

In the drawing 1 indicates a tubularcontainer filled with copper oxid 2, said copper oxid being so arranged in said tube and of such physical character as to be .readily permeated by the atmosphere to be tested. A thermostatic device, in this case a tube 3 provided with an expansion chamber 4 and electrical contacts 5 and 6 (said tube and .expansion chamber containing mercury 7)' is arranged in operative relatlon to said container 1 and said copper oxid filling 2. A source of heat 8 is provided in operative re lation to said container 1 and copper oxid filling 2, this" source of heat in this case conslsting of a receptacle 9 filled with a liquid bath 10, an inlet 11 for the renewal of said bath and a heating coil 12 for maintaining said bath at its boiling point. If desired a discharge 13 may be connected to said container l0,'said discharge 13 conducting the vapor evaporated from said bath to a suitable condenser, from whence it may be re turned to inlet 11. A casing 14 is adapted to inclose the apparatus, said casing being fitted with an inlet 15 and a discharge 16;

the function of said casing being to provide.

means whereby the atmosphere to be tested may be forced through the apparatus, drawn through by means of an exhauster, or insome cases automatically caused to flow through said apparatus by the chimney efi'ect produced by source of heat 8; and also to assist in isolating said apparatus from the exterior.

Electrical contact 5 is connected by means of circuit 17, source ofelectrical energy 18,

electrically operated alarm 19 and circuit 20 to electrical contact 6, said

contact

5 and 6 being adapted to be placed in circuit by therising of mercury in tube 3. Foraminous means, in this case gauzes 21and 22, may if necessary be provided for preventing propagation. of flame to the exterior atmosphere, and, together with casing 14, completely isolating the apparatus from the exterior.

The operation of the apparatus illustrated is as follows: Assuming the apparatus to be operating in normal atmosphere, the copper oxid filling 2 will reach its normal temperature and the mercury 7 will become heated thereby and rise to the level of normal operation indicated diagrammatically by the line AA.

Circuits

17 and 20 will not be energized as, although contact 5 is covered by the mercury in the lower portion of tube 3 and expansion chamber 4, said mercury will not rise to the level of contact 6 under conditions of normal. operation.

If now an atmosphere containing a combustiblegas, such as carbon monoxid, flow through the apparatus, heat will "be generated by tlieoxidation thereof caused by contact with copper oxid 2, the said copper oxid being maintained at a temperature which will cause the reduction of said oxid by carbon monoxid, but not at a high enough temperature to cause the combustion of the carbon monoxid, and the oxygen contained in the atmosphere. In other words, the copper oxid acts as a selective oxidizing agent for the oxidation of the carbon monoxid. A

The mercury 7 is now further heated by the heat liberated during this reaction and expands, rising "in tube 3 until, if the percentage of carbon monoxid be high enough to cause the required elevation'in temperature, it makes contact with electric contact 6,

closing circuits

17 and 20 and operating alarm 19, thus providing a warning .of the presence of a certain percentage of carbon monoxid.

If hydrogen. be passed through .the apparatus it will operate the device in approximately the same manner as though carbon monoxid were present, but as these two gases are almost invariably associated in many 10- cations where it is desirable to detect carbon monoxid, such'as in coal mines, the fact that the hydrogen will also operate the apparatus merely serves to reinforce the carbon monoxid warning, and as the two gases if simultaneously present will both assist in the operation of the apparatus, the combustion of the hydrogen will permit the detection of smaller quantities of the carbon monoxid than might otherwise be the case.

It, will of course be-understood that gases:

such as methane may be detected by the use of this apparatus provided that the oxidizing agent be maintained at a sufiiciently high temperature to cause the oxidation of the methane. This differential or'selective ac-' tion of the method is one of the principal objects of our invention, as it will enable the simultaneous and differential detection of different gases, such for example,'as carbon monoxid and hydrogen on the one hand and methane on the other hand.

To accomplish this end it is simply necessary to pass the suspected air throu h .aplurality of, a paratus of thev types own in the figure, t e first oxidizing chamber being maintained at a temperature that will oxidize the carbon monoxid and hydrogen but that will not aifect the methane, and the second 4 oxidizing chamber being maintained at a temperature that willoxidize the methane. If it be desired to make a further diflerentiation, it will be possible to remove the carbon monoxid or hydrogen by passing it through an oxidizing chamber maintained at a temperature that will oxidize the one but that is too low to' oxidize the other. It will of course be understood that when a plurality of combustion chambers are used for selectively detecting combustible gases of different composition, the signaling devices connected to the various combustion chambers may be separate so that a separate signal and apparatus will function in vitiated atmospheres that would not support the combustion of these combustible gases, due to the low oxygen percentage, or even to the absence'of ox gen.

As the maximum temperature that will be I reached by any definite ercentage of the combustible gas is fixed E 1, the heat of combustion of the gas, 2, the rate of flow of the gas, or gas and air, through the apparatus and '3, the rate of heat loss of the apparatus as a whole, it will. be clear that the two latter quantities are possible of control and that all three may be considered as constant for any given apparatus. Hence it is readily possible to so fix their relation that a definite predetermined percentage of the gas to be detected will be required to cause the operation of the thermostatic device and warning signal. Physical properties of the gas, such as specific heat, etc., may be con sidered to be approximately constant for the purpose of the operation of the apparatus.

It will be desirable torestrict the flow of the. air, or gas and air, to be tested through the apparatus in order to'keep the conditions constant, as outlined in the preceding paragraph. It is also necessary to maintain the oxidizing material at an approximately uniform temperature, and in certain cases this may be readily attained by preheating the'air, or gas and air, to' the desired tem-' perature prior to passing it over the oxidizing material. In such' cases it will not always be necessary to heat extraneously the oxidizing material, as the air to be tested may perform. this function.

.In certain cases a catalytic oxidizing material may be used, as for example, when hydrogen is to be detected, and under these conditions the initial rise in temperature of the oxidizing element maybe caused, or

assisted, by catalytic action.

It will be understood that a great variety of devices may be used in the operation of our method and in the construction of apparatus therefor, and it has not been deemed necessary to illustrate and describe at length a great number of different types and modifications of such apparatus. For example, the thermostatic element may be widely varied, as any type of thermostatic device in common use may be employed provided it possesses the necessary operating characteristics While the drawing shows an electrical connection between the signaling means and the thermostatic element, it will of course be understood" that other devices may be used therefor.

It will be understood that the invention may be-employed in either a stationary or portable form, and that one or more detectors may operate by remote control a single signal or that a plurality of signaling devices may be operated by one or more detectors. I

In the application for patent dated A ril 14, above referred to, a number of modi ca tions of apparatus are shown for carrying out the generic method of gas detection therein described and claimed, and it will be understood that many of these modifications may be employed with the present invention and also that the subject matter described and claimed herein is subject to the dominating features of the disclosures in said application for patent.

The operation of our invention is not limited to the use of copper oxid but depends upon the use of any metal, or metalloid, compound, containing oxygen, which whe maintained at suitable temperature will bause the-desired oxidation of the combustible gas which is to be detected, and the term oxidizing agent in the claims hereof, is used to. designate such compound.

In the operation of our invention it will of course be understood that the oxidizing agent, such as copper oxid, will become reduced by the passage of the combustible gas through it andv that this oxidizing agent may either be renewed from time to time or ma be re-oxidized by the action of a strong y oxidizing atmosphere.

Having described our invention we claim:

1. The method of detecting changes in the constituent gases of the atmosphere which consists in maintaining a'temperature responsive element in operative relation to an oxidizing agent and to a source of heat, said element being operatively connected to signaling means; in causing said element to 0perate said signaling means when the temperature of said element reaches a predetermined limit; and in permitting variations in the heat received from said source of heat, due to the chemical reduction of said oxidizing agent caused by changes in said constituent gases, to cause the temperature of said element to reach said limit; whereby said signaling means are operated and a warningof said changes given.

2. The method of detecting changes in the constituent gases of the atmosphere which consists in maintaining a temperature responsive element in operative relation to an'oxidizing agent and to a source of heat, said element being electrically connected to signaling means; in causing said element to operate said-signaling means when the oxidizing agent and to a source of heat, said element being operatively connected to signaling means; in causing said element to operate said signaling means when the temperature of said element reaches a predetermined limit; and in permitting variations in the heat received from said source of heat, due to the chemical reduction of said oxidizing agent caused by changes in said constituent gases, to cause the temperature of said element to reach said limit; whereby said signaling means are operated and a warning of said changes given, means being provided for preventing propagation of flame to the exterior.

4. The method of detecting changes in the constituent gases of the atmosphere which consists in maintaining a temperature responsive element in operative relation to an oxidizing agent and to a source of heat, said element being electrically connected to signaling means; in causing said element to operate said signaling means when the temperature of said element reaches a predeter mined limit; and in permitting variations in the heat received from said source of heat, due to the chemical reductionof said oxi dizing agent caused by changes in saidconstituent gases, to cause the temperature of said element to' reach said limit; whereby said signaling means are operated and a warning of said changes given, means bein provided for preventing propagation o 6. Apparatus for the detection of changes in the constituent gases of theatmosphere, comprising in combination an oxidizing agent, a source ofheat in operative relation thereto, a temperature responsive element in operative relation to said agent, and electrical signaling means operatively connected to said temperature responsive element.

In testimony whereof THOMAS M. CHANGE has signed his name at Philadelphia, Pennsylvania, the 28th day of April, 1917, and

VEDWIN M. CHANGE has signed his name at Wilkes-Barre, Pennsylvania, the 30th day of April, 1917.

THOMAS M. CHANCE. EDWIN M. CHANCE. Witnesses as to Thomas M. Chance:

H. M. CHANCE, CARL K. SoHULzE. Witnesses as to Edwin M. Chance:

G. W. REYNOLDS, JOSEPH FLUEGEL.