US2200523A - Gas detector - Google Patents

Description

W. G. TUEL GAS DETECTEUR May 14, 1940.

Filed Sept. 8, 1938 mu FNLT. VG N IM M L L W ATTORNEY Patented May 14, 1940 y GAS DETECTOR William G. Tuel, Indianapolis, Ind., assignor to The Prest-O-Lite Company, Inc., a corporation of New York Application September 8, 1938, Serial No. 228,899 2 oaims. (o1. .2a- 254) uis:

'Ihe invention relates to apparatus for detect- Y ing gases and `more particularly to. an improved apparatus for the detection of halogen compounds in gases. y

The use of organic halogen compounds, such as dichlorodiuoromethane and methyl and ethyl chlorides, in refrigeration apparatus has created a demand for a sensitive, reliable, and convenient device for detecting leakage i such compounds into the atmosphere. A widely used method for this vpurpose is a flame test in which a sample of the atmosphere to be tested is introduced into a ame and the name impingedon a heated reactive material, such as copper or nickel, causing a characteristic reaction and a change in the color of the iiame to occur if halides are present. In practice, the vflame consists of a small, blue inner cone surrounded by an outer envelope ranging in color from substantially colorless to. a yellowish tinge. The presence of halides causes an immediate and .distinct change'in the color of the outer envelope to green or blue-green.

The sensitivity of an apparatus employing the foregoing method depends largely on the opers ators ability to detect a slight color change in the ame imparted by small amounts of halide gases. The sensitivity is also dependent on the temperature of the reactive material and it has been proposed to employ a larger and more intense iiame to increase the temperature of such material; but the advantage obtained through the use of a. larger and more intense flame is counteracted by the diiiculty of .detecting the presence of only a slight color change in a ame of such size and type.

An object oi the present invention is to provide an improved apparatus including means for bringing the gas into contact with the reactive material under conditions which ensure the detection of halides in Very loW concentrations.

Another object is to provide an improved apparatus including means for ensuring a satisfactorily high operating temperature in the reactive material Without increasing the difliculty of detecting very small changes in flame color.

These and other objects are. attained in the present invention by the provision of a reactor plate of novel design Iwhich may readily be adapted for use with any apparatus employing substantially the foregoing method of halide gas detection. For convenience, the invention Will be described as it may be used in one typical variety of apparatus; but that it may be used with other varieties will be apparent. `In the drawing:

Fig. lis a front sectional View of a preferred l embodiment of the invention adapted for use with a halide gas detector apparatus employing acetylene as the combustible gas;

Fig. 2 is an end View of the embodiment of the invention shown in Fig. 1; f'

Fig. 3 is a sectional view taken on the line 3--3 'cf Fig. 2;

lFig. 4 is a sectional view of a second embodiment ofthe invention; land Fig. 5 is a sectional view oi a third embodiment of the invention.

Referring to the drawing, the apparatus head I-I.

The burner head H includes a longitudinally bored nozzle holder Irl, one end of which is mounted in theadapter I3. The opposite end of the nozzle holder lll supports a nozzle I5 which extends past the end of said holder. Also supportedl on the end of the nozzle holder I4 is a.v longitudinally bored member I6 which comprises air cooling fins I'I, a gas mixing chamber I8 and a combustion tip 3U. rI'he combustible gas necessary to provide a llame is introduced into said mixing chamber through the nozzle I5, and a sample of the atmosphere to be tested is introduced through a suitable tube I9 mounted in the Wall of the member IB. The gas mixture is conducted from the mixing chamber I8 through the bore of the member I6 to the combustion tip 30 enclosed within a cylindrical shield 2B which is supported by the member I6, The reactor plate holder 23 and a reactor plate 22 are mounted Within the shield 20, and a Window 2l is also provided in the said shield. When the combustible gas is ignited, the llame formed passes through the reactor plate 22,` heats said plate during its shown comprises a handle or grip Ilthrough passage, and is observed through the window 2l. v

The'reactorplate holder 23 comprises an L- shaped member provided with a centrally located opening so that the reactor plate 22 may be supported in the path of the flame. The reactor plate 22, which may be adapted in anysuitable manner to be mounted in the reactor plate holder 23, may be of copper or other material which is reactive to the gas suspected of being present in the atmosphere under test and which imparts a characteristic color to the ame when heated in the presence of such gas. To permit passage of the ame through the reactor plate 22, and to spread or broaden the flame into a ribbonlike or sheetlike shape as it enters the Vicinity of Ythe Window 2l, an elongated opening 24 is provided in said plate. Such an opening may be produced by boring two holes in the reactor plate 22, the center of each hole being at a slight distance from the center of `said plate, but so located that the intersection of 'the two holes formsan elongated opening centrally located with respect *to the passage of the flame through the reactor plate 22. It is essential that the opening, formed in the above or any other manner, impart :to y.a ame passing therethrough a Wide ribbonlike-or sheetlike shape. The surface of the reactor plate 22 against which the iame rst impinges is preferably shaped to form a concave opening.

An alternate embodiment of the invention (Fig. 4) comprises a reactor' plate 22 provided with a slot 2l which is preferably centrally located with respect to said plate. A concave surface 25 may be provided to facilitate the passage of the flame through the slots 2l.

Another embodiment of the invention (Fig. 5) comprises a reactor plate E2 provided with a plurality of holes 28 which may consist of one or more rows but so positioned that a flame passing therethrough will be spread to a ribbonlike or sheet-like shape. A concave surface 29 is preferably provided to direct the entrance of the ame into said holes.

A reactor plate provided with an elongated opening and concave surface as herein described ensures the attainment of a high temperature in said plate, thus increasing the sensitivity and reliability of the apparatus as compared with the same characteristics of a similar apparatus provided With a reactor plate having the usual circular opening. Also, the use of an elongated opening in the reactor plate tends to spread and increase 'the `area o'f the ame presented to the operators eye. This permits a=1nore accurate observation of the color characteristics of the iiame and ensures the positive detection of small amounts of the gases being detected.

1 claim:

1. .In an :apparatus for detecting halide gas,

.means for introducing such gas into an unignited stream ofifuel gas; means for burning such fuel gas, containing halide, as a substantially colorless ame; and an apertured reactor member so positioned Within the name that the ame impinges on the member and emerges through the aperture, said member being composed of ina- `terial .which Whenhot reacts with the halide to impart a color to the emergent flame, andsaid aperture being elongated transversely to the axis of the 'flame so that the emergent flame is in the shape oi a ribbon or sheet.

2. 'In Yan apparatus as dene'din claim 1, a reactor melnber'vvhich is provided witha concave surface on which the flame impinges, and with an elongated aperture formed by the intersection of a plurality vci' circular apertures.

G. TUEIL.

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