Unit Instruments, Inc.

Dan B LeMay

Kim Ngoc Vu

Eric J Redemann

Michael J Doyle

Robert Laragione

Michael D Upchurch

A thermal mass flow controller having a thermal mass flow meter with an orthogonal thermal mass flow sensor includes a base defining a primary fluid flow path therein for carrying a flow of fluid to be metered. A pressure dropping bypass is positioned in the primary fluid flow path. A flow measuring portion of a thermal mass flow sensor is oriented substantially transversely or orthogonally with respect to and is in communication with the primary fluid flow path. The flow measuring portion includes a portion of an electrical bridge for determining a temperature of the sensor and produces a mass flow rate signal in response thereto. A valve is connected to an outlet of the primary flow path to control the flow of fluid in response to the mass flow rate signal.

Thermal mass flow controller having orthogonal thermal mass flow sensor

Method and apparatus for determining a mass rate of flow of gas by a rate of change of pressure includes an inlet for communicating a flow of gas from a source of gas whose mass flow rate is to be measured. A volumetric container is connected to the gas inlet to receive the gas. The volumetric container precisely defines a standard volume in its interior. Positioned within the volumetric container is a heat conductive assembly for maintaining the interior of the system substantially isothermal during pressure changes of the gas as gas flows into or leaves the container. Attached to the container is a pressure measuring transducer which measures the gas pressure within the container. The rate of change of the gas pressure under isothermal conditions within the container is indicative of the rate of mass flow of the gas into or out of the volumetric container.

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Fallbrook, CA, United States of America

Dan B LeMay