The Foxboro Company

Robert C Prescott

Richard W Kalinoski

Edwin L Karas

Raymond Annino

Roy P Lindquist

A process chromatograph including a column for separating fluid samples into their individual components, and a density-responsive detector connected to the column output to produce a pressure signal representing the concentration of the separated components. The column and associated elements are contained within a thermally-insulated housing the interior spaces of which are heated and maintained at a set-point temperature by a temperature regulating system. Heat energy is supplied by steam to one section of a two-section tubular heat-exchanger. A stream of air is caused to flow through the other section and into the housing interior, to transfer heat thereto. The rate of heat transfer is automatically controlled by a thermostatic control which continuously adjusts the flow of air through the heat exchanger so as to maintain the interior temperature at a desired set-point.

Temperature control system for chromatographic apparatus

An all-pneumatic process chromatograph having a pneumatically-actuated sample-injection valve, an orifice connected in the column output line to develop a pressure signal corresponding to fluid density, a pneumatic amplifier for strengthening the pressure signal, and pneumatically-operated control means for developing a periodic sample-valve actuating signal and for selecting a particular peak of interest at a controllable time following injection of the sample. The pneumatic control means includes means automatically operable to adjust the time of peak selection in response to changes in actual peak elution time. The temperature-sensitive elements of the apparatus are contained in a chamber which is heated by a source of steam heat, with the rate of heat transfer being regulated pneumatically to maintain a relatively constant temperature within the chamber.

Pneumatic chromatograph

A pneumatic output signal limiting device utilizing a planar-type construction having a balance beam with a passage extending through the area of its pivotal axis to provide communication between side-by-side chambers and arranged so that the balance beam moves into contact with a valve in the output chamber to close the passage and further movement in the same direction open a vent. In operation, the output signal equals the input signal when the input signal is within one limit of a preselected output signal operating range. When the input signal equals the limit, the passage is closed and the output signal is maintained equal to the limit. The passage remains closed when the input is outside the limit and the output signal is maintained equal to the limit until the input signal is a preselected value outside the limit. Then the balance beam moves in the same direction to open the vent and reduce the output signal to the vent pressure. The device may be arranged for limiting either the high or the low limit of the preselected output signal operating range.

Growing community of inventors

Foxboro, MA, United States of America

Robert C Prescott