Abstract: A fixed-volume injector assembly having backflush capability is useful for injecting a sample into a gas chromatograph. The injector assembly has a sampling mode of operation, an injection mode of operation and a backflush mode of operation. In the sampling mode, sample is drawn into sampling chamber (11). In the injection mode, sample is injected into an injection channel which conducts the sample to a destination stream. In the backflush mode, carrier fluid flows through the injector assembly in the opposite direction. The injector assembly is designed to connect to precolumn (28) and analytical column (20) so that, in the backflush mode, precolumn (28) is backflushed. Advantages of the injector assembly include the ability to pressurize the sample before injection and to use a single carrier fluid source. In addition, the flow channels of the injector assembly are readily miniaturized.

Abstract: A detachable column cartridge for a gas chromatograph is disclosed. The cartridge column contains analytical and reference columns, a heater and a thermocouple, and connects via detachable connectors to a base unit containing an injector, a detector and other components normally found in gas chromatographs. The cartridge arrangement permits a substitute column to be connected to the base unit easily, in the field, when different gases are to be separated and analyzed. Also included are specific connectors for detachably connecting the columns with capillary tubes in the base unit of the gas chromatograph.

Abstract: A detachable column cartridge for a gas chromatograph is disclosed. The cartridge column contains analytical and reference columns, a heater and a thermocouple, and connects via detachable connectors to a base unit containing an injector, a detector and other components normally found in gas chromatographs. The cartridge arrangement permits a substitute column to be connected to the base unit easily, in the field, when different gases are to be separated and analyzed. Also included are specific connectors for detachably connecting the columns with capillary tubes in the base unit of the gas chromatograph.

Abstract: A compact and low fuel consumption flame ionization detector includes a precisely pored metallic disk or a silicon micro-machined diffuser plate through which the sample gas tube extends a minimum distance (less than 2 mm). The oxidant flows into the detector in a direction parallel to a plane of the diffuser plate, passes into a small cavity under the diffuser, and then passes through a large number of very small holes formed in the diffuser plate before encountering the sample gas flow at the end of the gas tube. A narrow diameter collector is closely spaced to the end of the gas tube. The direction of feeding the air and the diffuser plate (which acts as a baffle) provide laminar flow and eliminate the flicker noise which would otherwise occur due to the air flow inlet being located very close to the gas tube end. The FID is vertically compact and operates at a high electric field strength, exceeding 90 V/mm.

Abstract: A miniature gas chromatograph with thermostatically-controlled heating of its component parts which contact and conduct the sample to the analytical column. The microvalve assembly of the gas chromatograph is heated by passing a thermostatically-controlled electrical current through a metallic conductor formed on a surface of the microvalve assembly. The tubing which conducts sample from the gas chromatograph sample inlet to the microvalve assembly is heated by passing a thermostatically-controlled electrical current directly through the tubing or through a metal layer formed around the tubing. The sample inlet fitting is heated by a wire heater element wrapped around it. Each heater has an associated temperature sensor for controlling the amount of heating to maintain a predetermined temperature.

Abstract: An automated micro-valve assembly injects a fixed fluid volume fluid into a destination stream. The fluid to be injected (inject fluid) is conducted into a chamber. Flow of inject fluid out of the chamber is prevented by sealing the ends of the chamber using valves or by application of pressure. A fixed volume of inject fluid is injected into the destination stream by pressurizing the inject fluid in the chamber and opening an inject valve which connects the chamber to the destination stream. The pressurization of the inject fluid in the chamber above the destination stream pressure is effected by a T-valve which controls the flow of a purge fluid into the chamber. The purge fluid emitted by the T-valve flows toward the inject valve, forming a fluid-lock which establishes the fixed-volume to be injected. During the injection, the inject fluid is driven by the purge fluid pressure to flow through the inject valve into a destination passage which communicates with the destination stream.

Abstract: A detachable column cartridge for a gas chromatograph is disclosed. The cartridge column contains analytical and reference columns, a heater and a thermocouple, and connects via detachable connectors to a base unit containing an injector, a detector and other components normally found in gas chromatographs. The cartridge arrangement permits a substitute column to be connected to the base unit easily, in the field, when different gases are to be separated and analyzed.

Abstract: A gas chromatography assembly has a substrate wafer with grooves and a valve seat etched therein. A plate cooperates with the wafer and the grooves to define gas channels: a carrier gas channel and a sample gas channel, each passing through the valve seat. A valve actuator is attached to the valve seat for controlling the flow of sample gas from the sample gas channel into the carrier gas channel. A pump is attached to the wafer and is connected to the sample gas channel. The pump cooperates with the valve actuator to inject sample gas from the sample gas channel into the carrier gas channel. A modular capillary tube and a detector are connected to the carrier gas channel to analyze the properties of the sample gas flowing in the carrier gas channel from the sample gas channel.