Robert A Runyan

US Patent:

6575015, Jun 10, 2003

Filed:

Apr 24, 2001

Appl. No.:

09/841412

Inventors:

Teresa Lechner-Fish - Katy TX
Robert Jeffrey Runyan - Houston TX

Assignee:

Daniel Industries, Inc. - Houston TX

International Classification:

G01N 3004

US Classification:

73 2342

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 chromatographs 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.