Thermal gas flow meter working principle

Thermal gas flow meter is a kind of flow meter made according to the principle of medium heat transfer. It is generally used to measure the mass flow of gas. It uses the principle of thermal diffusion, and thermal diffusion technology is a technology with excellent performance and high reliability under harsh conditions. Typical sensor elements include two thermal resistors (platinum RTD), a speed sensor, and a temperature sensor that automatically compensates for changes in gas temperature. When two RTDs are placed in the medium, where the speed sensor is heated to a constant temperature above ambient temperature, another temperature sensor is used to sense the medium temperature. The mass flow of gas flowing through the speed sensor is calculated by the amount of heat transfer from the sensing element. As the gas flow rate increases, the amount of heat removed by the media increases. Causes the sensor temperature to decrease. In order to keep the temperature constant, the operating current through the sensor must be increased. This increased portion of the current is proportional to the flow rate of the medium.

Hot gas mass flow meters are mainly used to measure the following media: blast furnace gas, coke oven gas, gas, air, nitrogen, acetylene, phosgene, hydrogen, natural gas, nitrogen, liquefied petroleum gas, hydrogen peroxide, flue gas, methane , Butane, chlorine, gas, biogas, carbon dioxide, oxygen, compressed air, argon, toluene, benzene, xylene, hydrogen sulfide, sulfur dioxide, ammonia and other gases. According to the measured physical quantity, there are the following two kinds of measurement relationships:

1. The relationship between the change of the temperature field and the mass flow of the fluid generated when the fluid flows through the heating pipe;

2. It is necessary to increase the temperature of the fluid when it is heated by a certain value.