Sierra Instruments, Inc.

John George Olin

John P Smitherman

David Michael Korpi

Virgil Alan Marple

Norman C Ahlquist

Brian Estep

Donald I Ross

Capillary-type mass flow meters and controllers are described that employ temperature sensor hardware providing boundary conditions as necessary for direct computation of mass flow rate. The approach offers dramatically improved operable range and other potential benefits as compared to known systems.

Capillary sensor tube flow meters and controllers

Microprocessor-based thermal dispersion mass flow meters (i.e., thermal anemometers) are described that use temperature sensing elements in its flow sensor probe(s) in addition to the two elements commonly used. Such systems allow for automatically managing changes in gas selection, gas temperature, gas pressure, and outside temperature. One mass flow meter described has a flow sensor with four temperature sensing elements, wherein one pair is provided in a temperature sensor probe and another pair in a velocity sensor probe. Another variation operates without a separate temperature sensor probe and integrates all function into a single three-sensor probe. Such a device may also be used in conjunction with a one- or two-sensor temperature probe.

Mass flow meter configured with computational modeling for use with different fluids

A thermal anemometer or mass flow meter typically having temperature and flow velocity sensor elements is provided in which a thin film temperature sensor is used in the heated sensor of the fluid velocity sensor element of the system. At least one thin-film RTD sensor is held within a spacer or interface member and the spacer, optionally, received within a housing. The thermal anemometer is preferably constructed to offer sufficient precision and accuracy in its design to be suitable for sensitive scientific and industrial applications. This goal is achieved while using cost effective parts by employing a construction approach in which the spacer and RTD sensor(s) is secured in place by solder, braze or another compound flowed into place while inserting the spacer and/or sensor(s).

Mass flow meter with solder/braze-flow secured spacer

A thermal anemometer or mass flow meter having temperature and flow velocity sensor elements is provided in which a thin film temperature sensor is provided in the heated sensor of the fluid velocity sensor element of the system. The thin-film sensor is captured at least partially within a spacer or interface member, the spacer being received within a housing. The thermal anemometer is constructed to offer sufficient precision and accuracy in its design to be suitable for sensitive scientific and industrial applications. This goal is achieved while using cost effective parts&#x2014;as in the thin film temperature sensor(s)&#x2014;in connection with a construction approach minimizing or eliminating gaps or other system configuration variability.

Immersible thermal mass flow meter

Volumetric flow meters, volumetric flow controllers, mass flow meters, and mass flow controllers using a transverse laminar flow assembly are described. The flow assembly may be constructed from a plurality of open and/or closed slices or layers stacked upon one another and held together in compression by through bolts or another means. Meter or flow controller accuracy may be aided by use of flow conditioning features preceding an axial bore of the transverse flow assembly including one or more of a deflector, filter and nozzle.

Laminar flow meter or controller

An elongate temperature probe is provided for extending into a fluid flow. First an second temperature sensors are mounted in the temperature probe, spaced apart from each other along the length of the probe. The first and second temperature sensors provide temperature signals to a data processor. The data processor in use determines the temperature of the fluid flow from the temperature signals and at least one other fluid parameter, using a mathematical model of the heat transfer along the probe.

Dual element temperature sensing probe using a mathematical model of

A thermal mass flow rate sensor is made of a resistance temperature detector wire wound around a mandrel. A metal sheath is formed about the mandrel and wire assembly to be in intimate contact with the mandrel and wire assembly. The materials of which the sensor is made are selected such that their co-efficients of thermal expansion are approximately the same.

Thermal mass flow sensor

An improved mass flowmeter of the type having a primary passage for the fluid whose flow rate is to be measured, a sensor tube which serves as a secondary passage for the fluid and is connected to the primary passage at upstream and downstream locations, and a pair of resistance wire coils surrounding the sensor tube and connected to a bridge circuit in which the resistance differential between the wire coils is proportional to the fluid flow rate. The sensor tube is a straight tube displaced from the primary passage and accessible at its ends for cleaning. The wire coils and the corresponding portion of the sensor tube are surrounded by an evacuated enclosure to prevent convection effects between the adjacent coils, to maximize the response time of the coils to changes in fluid flow rate, and to reduce conduction losses.

Mass flowmeter

A multi-range gas flowmeter having a primary gas flow passage and a secondary passage which houses the flow measuring device and which is connected to the primary passage at its inlet and outlet ends. A multi-position valve is located in the primary passage between the inlet and outlet ends of the secondary passage to divert all or a portion of the flow to the secondary passage, depending upon the value of the flow rate to be measured.

Multirange flowmeter

A method and apparatus for sampling a particle-bearing gas in which a vacuum is applied to the gas to generate a stream of gas, the flow of the stream is maintained constant, and particles are collected from the stream. A constant flow controller responsive to the static pressure of the gas in the stream provides a flow restriction which gradually decreases to compensate for a gradually increasing flow restriction caused by particles collecting on an initially particle-free collection filter located in the stream.

Method and apparatus for sampling of a particle-bearing gas

An apparatus for the collection of particles from a gas containing particles which comprises a first means for directing the flow of said gas toward a second means for collection of at least a portion of said particles by the process of impaction, the first means containing inlet means which comprises at least one perforation having a length dimension which is greater than its width dimension and a third means between and contacting said first and second means and having an inner wall, which is a smooth closed curve, the third means being located relative to the inlet means and the third means having a configuration such that a substantial number of the streamlines of the flow of said gas after the impaction of at least a portion of said particles in said gas with the second means are in substantial parallelism to the curve of the wall of the third means; the first, second and third means forming an enclosed volume having the inlet means and outlet means for exit of the gas after the impaction of at least a portion of the particles in the gas with the second means.

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Carmel Valley, CA, United States of America

John George Olin