Abstract: An improved double block and double bleed stream switching system (modifiable to, for example, a double block, single bleed stream switching system) includes a common stream path for a multitude of gas streams from, for example, a process pipeline. The improved stream switching system includes a heating mechanism and insulation oven to help temperature stabilization, along with a structure to separate temperature sensitive solenoids from the heated area. Pre-heat coils are located between the sample switching system and the sample shut off system to warm the gas sample and to act as a flow restrictor. A first embodiment is suited for the Division 1 environment and a second embodiment is suited for Division 2 uses. The improved stream switching system may also feature membrane or cartridge filters located upstream of the sample wetted portion of the stream switching system.

Abstract: The invention is a gas chromatograph that includes a mechanism to heat the carrier gas to a temperature higher than that of the columns through which it flows. The carrier gas may be temperature programmed to achieve much the same results as the known technique of temperature programming the column.

Abstract: A gas chromatograph with multiple valves is disclosed. An embodiment of the multi-valve gas chromatograph includes multiple valves, multiple thermal conductivity detectors (TCD's), and a manifold. This allows separation and measurement of a gas sample in one compact integrated unit. The unit is particularly desirable because the solenoids associated with the valves are attached directly to the underneath of the manifold, thus eliminating the need for tubing between the solenoids and the valves. Other features may also be present. For example, a leak free multi-valve block may include a first temperature zone heating the valves and detectors and a second temperature zone heating the columns. The leak free feature may be achieved by placement of tightening screws through the center of each valve. Carrier gas insertion areas may be provided in the multi-valve block to improve performance.

Abstract: A novel gas chromatograph includes suitably located backpressure restrictors. In a preferred embodiment, each backpressure restrictor consists of capillary tubing with a pressure drop across it controlled to be less than or slightly greater than 0.528. One embodiment places the backpressure restrictor upstream of an initial stream switching valve and downstream of sample pre-heat coil. Another embodiment places the backpressure restrictor downstream of the gas chromatograph's measurement element and its carrier pre-heat coil. In each case, only a controlled and predictable flow rate is achieved, both regulating the flow rate through the system and back pressuring fluid to remain in the respective pre-heat coils to achieve ideal temperature.

Abstract: The invention is a gas chromatograph that includes a mechanism to heat the carrier gas to a temperature higher than that of the columns through which it flows. The carrier gas may be temperature programmed to achieve much the same results as the known technique of temperature programming the column.

Abstract: A novel stream switching system includes a unitary housing having a common stream path for a multitude of fluid streams from, for example, a process pipeline. A set of solenoids or other switches attached to the housing directly controls the flow of each fluid stream. Preferably, the solenoids are default-closed, low dead-volume solenoids that, unlike conventional low dead volume solenoids, are closed if not supplied with electricity. These solenoids are adapted to the wide temperature ranges encountered in the pipeline environment by increasing the voltage applied to the solenoids. The housing also preferably includes a pre-heat region to warm the sample to a desired temperature.

Abstract: A novel stream switching system includes a unitary housing having a common stream path for a multitude of fluid streams from, for example, a process pipeline. A set of solenoids or other switches attached to the housing directly controls the flow of each fluid stream. Preferably, the solenoids are default-closed, low dead-volume solenoids that, unlike conventional low dead-volume solenoids, are closed if not supplied with electricity. These solenoids are adapted to the wide temperature ranges encountered in the pipeline environment by increasing the voltage applied to the solenoids. The housing also preferably includes a pre-heat region to warm the sample to a desired temperature.

Abstract: A novel gas chromatograph includes suitably located backpressure restrictors. In a preferred embodiment, each backpressure restrictor consists of capillary tubing with a pressure drop across it controlled to be less than or slightly greater than 0.528. One embodiment places the backpressure restrictor upstream of an initial stream switching valve and downstream of sample pre-heat coil. Another embodiment places the backpressure restrictor downstream of the gas chromatograph's measurement element and its carrier pre-heat coil. In each case, only a controlled and predictable flow rate is achieved, both regulating the flow rate through the system and back pressuring fluid to remain in the respective pre-heat coils to achieve ideal temperature.

Abstract: A gas chromatograph with multiple valves is disclosed. An embodiment of the multi-valve gas chromatograph includes multiple valves, multiple thermal conductivity detectors (TCD's), and a manifold. This allows separation and measurement of a gas sample in one compact integrated unit. The unit is particularly desirable because the solenoids associated with the valves are attached directly to the underneath of the manifold, thus eliminating the need for tubing between the solenoids and the valves.

Abstract: A gas chromatograph with multiple valves is disclosed. An embodiment of the multi-valve gas chromatograph includes multiple valves, multiple thermal conductivity detectors (TCD's), and a manifold. This allows separation and measurement of a gas sample in one compact integrated unit. The unit is particularly desirable because the solenoids associated with the valves are attached directly to the underneath of the manifold, thus eliminating the need for tubing between the solenoids and the valves. Other features may also be present. For example, a leak free multi-valve block may include a first temperature zone heating the valves and detectors and a second temperature zone heating the columns. The leak free feature may be achieved by placement of tightening screws through the center of each valve. Carrier gas insertion areas may be provided in the multi-valve block to improve performance.

Abstract: An improved double block and double bleed stream switching system (modifiable to, for example, a double block, single bleed stream switching system) includes a common stream path for a multitude of gas streams from, for example, a process pipeline. The improved stream switching system includes a heating mechanism and insulation oven to help temperature stabilization, along with a structure to separate temperature sensitive solenoids from the heated area. Pre-heat coils are located between the sample switching system and the sample shut off system to warm the gas sample and to act as a flow restrictor. A first embodiment is suited for the Division 1 environment and a second embodiment is suited for Division 2 uses. The improved stream switching system may also feature membrane or cartridge filters located upstream of the sample wetted portion of the stream switching system.

Abstract: A gas chromatograph with multiple valves is disclosed. An embodiment of the multi-valve gas chromatograph includes multiple valves, multiple thermal conductivity detectors (TCD's), and a manifold. This allows separation and measurement of a gas sample in one compact integrated unit. The unit is particularly desirable because the solenoids associated with the valves are attached directly to the underneath of the manifold, thus eliminating the need for tubing between the solenoids and the valves.