Patent GB-405379-A (GB)
Title: Improvements in apparatus for gas analysis, particularly for the eudiometric estimation of gaseous mixtures containing firedamp
IPC: G01N7/06
Filed: 1932-09-12
Abstract: Eudiometers.--In apparatus for measuring variations of gaseous volume resulting from chemical reaction, particularly suitable for firedamp measurements, two chambers a<1>, a<2> containing two precisely similar gas masses under substantially the same conditions of temperature and pressure are connected one to each of the two branches of a manometer c and means are provided for placing one only of the chambers in communication with the atmosphere after the reaction has been effected.  In the construction shown two circular plates d, e, Figs. 1 and 2, preferably of brass, are superposed with plane surfaces in contact under pressure of a spring g<3> and the chambers a<1>, a<2> are constituted by cavities, two in each plate, symmetrically arranged in relation to the axis, the edges of the two cavities in one plate coinciding with the edges of the two cavities in the other.  The plate d is mounted to slide without rotation in a tube g enclosing the manometer c and fixed to a miner's lamp f, and the plate e is fixed to a tube i mounted to rotate in the tube g and is provided with passages i<0>, Fig. 2, connecting the chambers a<1>, a<2> each with a branch of the manometer.  The chamber a<1> communicates also by a passage j<0> with a chamber j in the plate d, this chamber being normally closed by the end k of a spring-pressed plunger. The plate e and tube i are fixed to a ring j<1> provided with handles i<1>, i<2>, Fig. 2, fo effecting the rotation, these handles being provided with conduits which, upon rotation of the plate e through 90 DEG  from the position shown in Figs. 1 and 2, are aligned with conduits d<0> in the plate d to place the chambers a<1>, a<2> i communication with the atmosphere. The gaseous mixture to be tested is introduced through the conduit in one of the handles i<1>, i<2> <PICT:0405379/III/1> <PICT:0405379/III/2> <PICT:0405379/III/3> <PICT:0405379/III/4> <PICT:0405379/III/5> and the plate e is turned through 90 DEG  to the position of Figs. 1 and 2.  Explosion is then effected simultaneously in the chambers a<1>, a<2> by passing a current through wires b therein. These wires are preferably of slightly differing resistance, so that a slight difference of temperature at the time of explosion permits a slight variation of the liquid levels in the manometer, indicating that explosion has occurred.  The closure k is then lifted to admit air to the chambers j and a<1> and the difference of level in the two branches of the manometer, as read on a scale q<4>, Fig. 6, gives a measure of the amount of firedamp present.  To facilitate the reading the manometer is provided with a device for bringing the liquid level in one branch opposite one of the scale divisions, such device comprising a cylindrical reservoir q<5> communicating with the two branches and fitted with a piston q adjustable by a screwed rod q<1> rotatable from a button q<2> through a clutch q<3>.  Attachment to lamp.  The tube g comprises an upper part g<1> and a lower part g<2> each mounted in a collar h carried by the lamp f which is screwed into the top of a battery casing r<1>, and to prevent any dismounting of the testing apparatus while the lamp is screwed in position, a member r, screwing into the collar h into locking engagement with the tube g<1>, is accessible only when the lamp is unscrewed and removed from the casing r<1>.  A finger s engaging in an annular groove in the member r prevents its complete removal.  Supply of current.  The collar h carries two battery contacts connected the one to a fixed contact n<1> at the lower end of a axially arranged conductor m<1> and the other to a spring blade n<2> which, when the plate e is in the position for effecting the explosion, is directly beneath the end of a second conductor m<2>.  The wires b are each carried by a pair of plugs t<1>, t<2>, Figs. 7 and 8, fitting into corresponding insulated sockets in the plate e and these sockets are so connected to the conductors m<1>, m<2> that, on pressing the blade n<2> against the conductor m<2> by means of a push-button p, current passes through both wires b.  To facilitate the mounting of the plugs t<1>, t<2> carrying the wire b in their sockets and their withdrawal therefrom the tool shown in Figs. 7 and 8 is provided.  This comprises a spring clip u provided at its free edges with cavities u<2> spaced correspondingly to the sockets, the clip being opened by a wedge u<1> on an operating stem u<11>.