Capillary-type mass flow meter

Official URL: https://dx.doi.org/10.1201/9781315217109-58

In many processes, mass flow rate, rather than volume flow rate, is the desired parameter because volumetric flow measurements are less reliable than are mass flow measurements. Since changes in gas temperature and pressure will affect the density of a fixed volume of gas, thermal mass flow meters and controllers, unlike rotameters, turbine meters, and other volumetric flow devices, are relatively immune to changes in inlet temperature and pressure. Because these instruments directly measure molecular flow, they provide the most reliable, repeatable, and accurate method for delivering material from a supply volume to a process at a desired rate. Features, such as direct electronic readout, fast response, exceptional sensitivity at low flow rate, negligible pressure drop, no moving parts, simple installation, unobstructed straight through flow path, absence of temperature or pressure corrections, and superior retain accuracy over a wide range of flow rates, make thermal mass flow meters a superior alternative to conventional flow meters in many important applications. Some other advantages of this type of flow meter are accuracy in a 2% range, low flow sensitivity, reliability, and long life with advances in electronic technology; in a sense, these flow meters are getting smarter and more capable with microprocessor computing power, thus expanding the range of their usage.