Method and apparatus for analyzing gases

Claim 1

In a chromatograph apparatus of the type comprising: (1) at least one body of adsorptive material, each such body having an inlet and an outlet, and each having the properties of adsorbing one or more components of a gaseous mixture to be analyzed, of allowing one or more of the adsorbed components to be eluted by passage of an inert carrier gas through the body and, where two or more gaseous components are to be adsorbed by and eluted from a single body, of causing elution of such components in time ordered sequence such that the eluted components are not commingled in the gas leaving the outlet of such body, (2) a detector having a gas inlet, a gas outlet and sensing means between the inlet and outlet in operative contact with gas flowing through the detector from the inlet to the outlet and capable of determining the composition of the gas, the improvement which comprises: (a) a first gas circuit connected to the detector inlet and including as a portion thereof said body or bodies of adsorptive material whereby gas introduced into the first gas circuit flows through such body or bodies and through the detector from its inlet to its outlet, (b) a second gas circuit having an inlet end and an outlet end and which is parallel to a portion of said first gas circuit, said second circuit being connected as its inlet end to the first circuit by a first valve means and being connected at its outlet end to the first circuit by a second valve means, said second gas circuit including a sampler element for receiving a predetermined volume of gas to be analyzed, said second gas circuit being located upstream in relation to said body or bodies, (c) valve operating means for said valve means operable automatically to carry out the following cycle of operation: (i) acting initially to route carrier gas solely through the first gas circuit from the detector inlet, through the detector to the detector outlet, (ii) then acting upon commencement of analysis to route carrier gas through said first valve means to said second gas circuit to propel said sample of gas from the sampler through said second valve means, thence through the remainder of said first gas circuit including said body or bodies of adsorptive material to the detector inlet, and (iii) after said sample of gas has been propelled beyond said second valve means, acting to re-establish flow of carrier gas solely through said first circuit.

Claim 4

A method of gas analysis by selective adsorption of one or more components of a gaseous mixture by a body of adsorptive material, elution of one or more of the adsorbed components and flow of the eluted gas through a detector which senses the composition of the gas, said method comprising the following steps: (a) a first causing flow of a carrier gas through said detector, (b) then interrupting such flow of carrier gas and propelling a sample of gaseous mixture to be analyzed through said body of adsorptive material and then through said detector, said material and its geometry being selected to adsorb one or more components of the sample, to allow elution of one or more of the adsorbed components by a stream of carrier gas and where two or more components are to be adsorbed, eluted and determined, allowing elution of each such component separately and without overlap with any other eluted component of the gaseous mixture, (c) then restoring flow of carrier gas through said body of adsorptive material to effect elution, (d) step (c) being carried out after a very short interval of time following step (b) to allow the sample at least to reach the adsorptive material without being mixed with carrier gas, such interval being short enough to minimize inaccuracies resulting from delayed restoration of flow of carrier gas.

Claim 5

A method of gas analysis by selective adsorption of one or more components of a gaseous mixture by a body of adsorptive material, elution of one or more of the adsorbed components and flow of the eluted gas through a detector which senses the composition of the gas, said method comprising the following steps: (a) a first causing flow of a carrier gas through said detector, (b) then interrupting such flow of carrier gas and propelling a sample of gaseous mixture to be analyzed through said body of adsorptive material and then through said detector, said material and its geometry being selected to adsorb one or more components of the sample, to allow elution of one or more of the adsorbed components by a stream of carrier gas and where two or more components are to be adsorbed, eluted and determined, allowing elution of each such component separately and without overlap with any other eluted component of the gaseous mixture, (c) then restoring flow of carrier gas through said body of adsorptive material to effect elution, (d) step (c) being carried out after a very short interval of time following step (b) to allow the sample at least to reach the adsorptive material without being mixed with carrier gas, such interval being short enough to minimize inaccuracies resulting from delayed restoration of flow of carrier gas.