Who were some of the pioneers in thermal mass flow technology?
A. Thermo-Systems, Inc. (TSI) began in its founder’s basement in 1959, with a cooled-film anemometer designed for transient measurements in high temperature fluid flows. This led to TSI’s hot-film and hot-wire anemometers, the first commercial products of this type. These immersion-type devices were used mainly as research instruments, many related to environmental pollution.
Tylan Instruments was another pioneer in thermal flow technology. In the early 1960’s, Tylan developed the first capillarytype thermal instrument to regulate gases used for chemical vapor deposition in the semiconductor industry. These mass flow controllers (MFCs) utilize two resistance temperature (RTD) coils around a capillary sensing tube to measure mass flow, and an integral control valve to regulate the flow.
Both instrument types use the thermal principle, but most manufacturers have concentrated on development of either the immersion-type or the capillary-type device. Sierra enjoys a unique position in the thermal technology field, because the company has been designing and manufacturing both types of instrument for the last thirty years.