Thermal mass flow transmitter
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Overview of Thermal mass flow transmitter
Thermal mass flow transmitter technology means Thermal gas flowmeters take gas measurement with digital transmitter. Thermal mass flow transmitter can directly measure gas mass flow rate and total flow and transmit the information by 4-20Ma or RS485 MODBUS. Thermal dispersion flow meter has high repeatability, high reliability, high stability and high accuracy. Thermal mass flow sensor has high sensitivity at the measurement site, especially for large pipe diameters and low flow rate gas measurement, can be used as large pipeline gas or air flow meter, flow measurement in large diameter pipes.
Thermal gas mass flow meters are widely used in on-site gas flow measurement due to their advantages of very small pressure loss, diverse mechanical structures, flexible installation, and convenient use, low price gas mass flow meter.
Principle of Thermal mass flow transmitter
Thermal gas mass flow transmitter probe has two temperature sensors, one of which is a temperature sensor to measure the temperature of the gas medium in the pipeline, and the other is a medium speed sensor. The temperature of the speed sensor is heated to a higher temperature than the temperature measured by the temperature sensor through electrical heating. And keep the temperature difference between the two sensors constant. When the gas medium flows and takes away the heat on the speed sensor, the bridge circuit on the meter head keeps the temperature difference between the two sensors constant, and the speed sensor needs additional electrical compensation heating. In practical applications, temperature sensors usually use Pt1000 or Pt300, and speed sensors generally use Pt20.
Thermal mass flow transmitter applications
Thermal mass flow transmitter measurement technology can take below gas mass flow measurement: air, compressed air, carbon dioxide (CO2), methane (biogas) and oxygen(O2), nitrogen ( N2), flue gas, duct gas, stove flue gas , furnaces gas, natural gas, compressed gas, etc.
Digital Thermal Gas Flow transmitter
Thermal mass flow measurement is a kind of modern and advanced gas measurement, without temperature and pressure correction, Thermal flow transmitter can directly measure gas mass flow .It is a kind of digital mass flow transmitters. There are many types of electronic thermal gas mass flowmeters used in industrial fields, and the instrument parameter configurations by digital LCD display are also different. Taking the thermal gas mass flow transmitter of Silver Automation Instruments Company in the China as an example, the terminals of the digital flow converter include: AC220V power supply, DC24V DC Power supply; instantaneous flow rate 4mA ~ 20mA signal output, working condition temperature 4mA ~ 20mA signal output (option), working condition gauge pressure 4mA ~ 20mA signal transmitter output (some working conditions do not perform temperature and pressure compensation on site, so thermal probes do not have temperature and pressure Measurement function), flow pulse signal output; serial RS485 data communication interface; relay Alarm output interface. The liquid crystal of the flow transmitter adopts a compact dot-matrix liquid crystal. After power-on, the electronic transmitter can shows the product version number, instrument factory serial number, gas flow meter upper limit, Gas medium type and Tag identification. Due to the limited space of the LCD display, one page cannot display all the metering data and configuration parameters. The measurement data of the thermal flowmeter includes instantaneous flow, total flow, working temperature, total gas flow. The thermal dispersion flow meter head can also set upper or lower limit alarm actions according to the process requirements in the field.
According to the pipeline information, it is also necessary to set the inner diameter of the pipeline (used for the conversion of the factory calibrated flow rate, and not used for the calibration flow rate of the factory with a pipe section), the roughness of the inner wall of the pipeline (different pipeline materials will affect the accuracy of gas measurement, such as carbon steel and stainless steel. Under the pipeline, the instantaneous flow value of the gas will change slightly). Set the instantaneous flow unit, working condition temperature unit, working condition pressure unit, set working condition pressure value, instrument correction factor, low flow cutoff, calibration date, and current output channel 4mA and 20mA calibration,4mA pressure lower limit value, 20mA pressure upper limit value, 4mA temperature lower limit value, 20mA temperature upper limit value, damping filter value (1 to 200). In addition to setting parameters through the keys of the instrument, the configuration software of the upper computer supporting the instrument can also be connected to the instrument through RS485 to realize the real-time collection and recording of measurement data and the setting of configuration parameters.
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