Talk:Thermal mass flow meter

This article is quite narrow minded and focussed just on one design. It states that the most common thermal mass flow meter type in industry "is not the subject of this discussion." Only one special type of thermal mass flow meters is described sufficiently. However the naming for this "Thermal Dispersion Mass Flow Meters" is misleading. The thermal dispersion principle is even used sometimes for the other principle mentioned in the article (capillary type)

So the headline should get changed to "Thermal Dispersion Flow Meters for Gasses - Insertion Type".

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This talks about three types but only two are discussed.

The capillary type should be added to this page. Eadkins73 (talk) 22:19, 25 August 2015 (UTC)eadkins73

Unsourced material

Article has been tagged for needing sources long-term. Feel free to reinsert the below material with appropriate references. DonIago (talk) 15:07, 12 February 2016 (UTC)

In operation

==In operation== Thermal mass flow meters are used almost entirely for gas flow applications. As the name implies, thermal mass flow meters use heat to measure flow. Thermal mass flow meters introduce heat into the flow stream and measure how much heat dissipates using one or more temperature sensors. The amount of heat lost from the sensor is dependent upon the sensor design and the thermal properties of the fluid. The thermal properties of the fluid can (and do) vary with pressure and temperature; however, these variations are typically small in most applications. In these applications where the thermal properties of the fluid are known and relatively constant during actual operation, thermal flow meters can be used to measure the mass flow of the fluid because the thermal flow measurement is not dependent upon the pressure or temperature of the fluid. This method works best with gas mass flow measurement because it is difficult to get a strong signal using thermal mass flow meters in liquids, due to considerations relating to heat absorption. While all thermal flow meters use heat to make their flow measurements, there are two different methods for measuring how much heat is dissipated. Constant temperature differential One method is called the constant temperature differential method. Thermal flow meters using this method have two temperature sensors — a heated sensor and another sensor that measures the temperature of the gas. Mass flow rate is computed based on the amount of electrical power required to maintain a constant difference in temperature between the two temperature sensors. Constant current A second, and more popular concept, is called the constant current method. Thermal mass flow meters using this method also have a heated sensor and another one that senses the temperature of the flow stream. The power to the heated sensor is kept constant. Mass flow is measured as a function of the difference between the temperature of the heated sensor and the temperature of the flow stream. Both methods are based on the principle that higher velocity flows result in a greater cooling effect. Both measure mass flow based on the measured effects of cooling in the flow stream.