Fluid flow control system

Claim 2

A flow control system for maintaining a substantially constant flow of fluid sample into a chamber comprising; a. conduit means, including upstream and downstream flow restriction means in series with each other, for conducting the fluid sample to said chamber; b. bypass flow means connected between said flow restriction means, said bypass flow means including suction means for drawing off a portion of the fluid sample that has passed through said upstream flow restriction means; c. means establishing communication between the inlet of said suction means and a source of supplementary fluid; and d. means located in said communication means for regulating the quantity of supplemental fluid drawn to said suction means, to thereby influence the pressure between said upstream and downstream flow restriction means and the flow of fluid sample to said chamber.

Claim 3

The instrument of claim 1 in which the regulating means comprises a housing, a movable diaphragm separating the interior of said housing into a reference chamber and a regulated pressure chamber, a baffle separating the regulated pressure chamber from an inlet chamber, and a valve member attached to said movable diaphragm for movement toward and away from a valve seat located in said baffle, said regulated pressure chamber being connected between said upstream and downstream flow restriction means, and said inlet chamber being connected to said source of supplemental fluid.

Claim 4

An instrument according to claim 1 wherein said fluid sample and said supplementary fluid are gaseous.

Claim 5

An instrument according to claim 1 wherein said suction means comprises a pump.

Claim 6

In an instrument for measuring analytically the amount of a gaseous constituent in a gaseous sample mixture by introducing the gaseous sample mixture into a reaction chamber and measuring a characteristic of the gaseous constituent within the reaction chamber, a flow control system for maintaining accurate flow of the gaseous sample mixture into the reaction chamber comprising: a. an upstream flow restricting device and a downstream flow restricting device in series with each other for conducting the gaseous sample mixture to the reaction chamber; b. bypass flow means connected to the junction of the upstream flow restricting device with the downstream flow restricting device, said bypass flow means including a bypass pump for drawing off a portion of the gaseous sample mixture that has passed through the upstream flow restricting device and means connecting the inlet of said bypass pump to a source of supplemental gas; c. regulating means located in said connecting means for regulating the flow of supplemental gas to said bypass pump and thereby influencing the pressure at the junction of the flow restricting devices; and d. an exhaust pump connected to the reaction chamber for drawing gaseous sample mixture from the junction of the flow restricting devices through the downstream flow restricting device and into the reaction chamber.

Claim 7

In an instrument for measuring analytically the amount of a gaseous constituent in a gaseous sample mixture by introducing the gaseous sample mixture into a reaction chamber and measuring a characteristic of the gaseous constituent within the reaction chamber, a flow control system for maintaining accurate flow of the gaseous sample mixture into the reaction chamber comprising: a. an upstream flow restricting device and a downstream flow restricting device in series with each other for conducting the gaseous sample mixture to the reaction chamber; b. bypass flow means connected to the junction of the upstream flow restricting device with the downstream flow restricting device, said bypass flow means including a bypass pump for drawing off a portion of the gaseous sample mixture that has passed through the upstream flow restricting device and means connecting the inlet of said bypass pump to a source of supplemental gas; c. regulating means located in said connecting means for regulating the flow of supplemental gas to said bypass pump and thereby influencing the pressure at the junction of the flow restricting devices; and d. an exhaust pump connected to the reaction chamber for drawing gaseous sample mixture from the junction of the flow restricting devices through the downstream flow restricting device and into the reaction chamber.

Claim 8

An instrument according to claim 5 wherein said connecting means connects the inlet of said bypass pump to the atmosphere.

Claim 9

An instrument according to claim 5 in which the reaction occurring within the reaction chamber produces chemiluminescence.

Claim 10

An instrument according to claim 5 in which the regulating means comprises a housing, a movable diaphragm separating the interior of said housing into a reference chamber and a regulated pressure chamber, a baffle separating the regulated pressure chamber from an inlet chamber, and a valve member attached to said movable diaphragm for movement toward and away from a valve seat located in said baffle, said regulated pressure chamber being connected to the junction of said flow restricting devices, and said inlet chamber being connected to said source of supplemental fluid.