ABSTRACT
Thermal flowmeters can be divided into two categories: Flowmeters that measure the rise in temperature of the fluid after a known amount of heat has been added to it. They can be called heat transfer flowmeters. Flowmeters that measure the effect of the flowing fluid on a hot body. These instruments are sometimes called hot wire probes or heated-thermopile flowmeters. Both types of flowmeters can be used to measure flow rates in terms of mass, a very desirable measurement, especially on gas service. The temperature sensors and the heater must protrude into the fluid stream. Thus, these components are easily damaged by corrosion and erosion. Furthermore, the integrity of the piping is sacrificed by the protrusions into the fluid stream, increasing the danger of leakage. In order to make the heat-transfer-type flowmeter suitable for the measurement of larger flow rates, the bypass designs have been introduced.
