Thermal gas mass flow meter

Thermal gas mass flow meter

Product Details

First, the working principle

The thermal gas mass flow meter is a flow meter based on the principle of thermal diffusion. The thermal diffusion technology is a technology with excellent performance and high reliability under severe conditions, that is, how much heat is lost when a fluid flows through a heat generating object. A certain proportional relationship with the flow rate. Specifically, the flowmeter's sensor has two standard-grade platinum RTDs, one for the speed sensor and the other for the temperature sensor that automatically compensates for gas temperature changes. When the two platinum RTDs are placed in the medium, the speed sensor is heated to a constant temperature difference above ambient temperature and the other temperature sensor is used to measure the temperature of the medium. When the medium flows through the velocity sensor, the mass flow of the gas is calculated by the amount of heat transfer from the sensing element. As the velocity of the gas increases, the amount of heat transferred to the medium by the sensor increases, so the temperature difference between the two and the flow rate In a linear relationship. The meter is converted to a linear output that measures the flow signal through this relationship.

Formula: P/△T=A+B(Q)N

Among them: P---dissipated power, △T---the temperature difference between the two sensors, Q---mass flow, N---exponential coefficient, A, B are the coefficients related to the thermal properties of the gas

As can be seen from the above formula, there are two options for manufacturing a flowmeter using the principle of thermal diffusion:

First, based on the principle of constant temperature difference: △T remains unchanged, and p and Q become incremental functions of exponential function;

The second is based on the principle of constant power: the dissipated power P is constant, and ΔT and Q are exponentially decreasing;

Second, the scope and characteristics of the use of thermal gas mass flowmeter

● Adopt high thermal resistance RTD sensor;

Proprietary flow data calculation for high performance, high precision and high repeatability;

● Adopt proprietary technology “balanced structure package”, automatic compensation of medium temperature;

● High-performance intelligent microprocessor and analog-to-digital and digital-to-analog conversion chips;

● The range ratio is 1:1000; it can realize large-caliber low-flow flow measurement, negligible pressure loss, and the minimum flow can be measured down to 0.05m/s;

No moving parts, the vibration effect can be ignored;

Selection, installation, use and maintenance are simple, and can be continuously disassembled and maintained online (plug-in type);

● It has nothing to do with the temperature and pressure of the medium;

Type 12-point dynamic correction for the flow signal, and built-in 10-point correction;

● It is not sensitive to small particles such as dust and is suitable for all kinds of single or mixed gas flow measurement.

proprietary high temperature algorithm medium temperature up to 510 ° C ;

● Straight pipe requirements are not high 1-2D

● Online dynamic correction of current and voltage output;

Third, the thermal gas mass flowmeter has its unique characteristics, so it can provide a popular solution for all walks of life.

Oil and natural gas: gas metering, natural gas measurement, energy exchange, leakage gas measurement, monitoring of flare gas;

Chemical industry: gas flow metering of induced draft fan, ammonia gas measurement, battery factory, flue gas circulation monitoring, gas flow metering in sampling system, various gas flow measurement;

Engineering - monitoring of electricity, gas and water treatment,   Measurement of various high purity gases in the laboratory , pipeline gas, biogas, gas, natural gas, liquefied gas, boiler preheated air, etc.;

Power industry: measurement of gas in boilers and auxiliary systems, measurement of primary and secondary winds in power plant blast furnaces, gas measurement in gas distribution process in fuel systems, gas measurement in gas furnaces;

Metallurgical industry: measurement of coke oven gas in coking plant, measurement of blast furnace gas in ironmaking plant, gas metering in steel plant, measurement of furnace gas in Handan Iron and Steel Plant, powder/steam ratio control in pulverized coal combustion process , hydrogen in heat treatment quenching furnace Control of gases such as oxygen and nitrogen, and control of the discharge gas flow in the vertical mill of the cement industry ;

Food and pharmaceutical industry: carbon dioxide treatment in brewery, gas flow measurement in thermal oxidation process, addition of fresh air in processing operation, hot air flow in bottle sterilizer, boiler intake, ventilation system, exhaust gas control;

Paper industry: gas measurement in wastewater treatment system, secondary and tertiary air recovery of boilers, flue flow monitoring, gas and air supply measurement of boilers;

Fourth, the hot gas performance table                  

Applicable medium Moisture-free gas
Measuring range 0~60m/s (standard state is 20°C, 0.10133MPa), please exceed the measurement range and negotiate with the manufacturer.
Accuracy ±1% of reading, ±0.5% of full scale
Repeatability 0.2% full scale
temperature range Ambient temperature -20 ° C ~ 70 ° C; medium temperature -20 ° C ~ 120 ° C or -20 ° C ~ 350 ° C
Power supply 24VDC/220VAC
Analog output 4~20mA/DC
Response time ≤1 second
Temperature Coefficient 0.05%/°C
Communication Interface Serial output RS485/HART
Online display LCD display instantaneous / cumulative flow and heat
Process pressure ≤4.2MPa (more than this pressure needs to be negotiated with the manufacturer)
Process connection Locking device / ball valve connection, flange connection, flange card loading, if you need other installation methods, you need to negotiate with the manufacturer in advance.
Explosion-proof grade ExdIIct4
Protection level Sensor IP67; transmitter IP65
Alarm point Relay dry contact output, select upper limit single alarm point or upper and lower limit double alarm point
Sensor diameter 3mm/4mm/5mm
Probe diameter The standard is 18mm. For special requirements, please contact the manufacturer to negotiate custom.
Sensor material The standard is 1Cr18Ni9Ti; 304L; Ha C;
Probe material The standard is 1Cr18Ni9Ti; 304L; Ha C;
shell material Hazardous area installation of shell-coated aluminum castings
Electrical interface M20×1.5
Pressure loss For pipes larger than DN80, the diameter is negligible


Five, mass flowmeter air flow range reference                                                              

DN (mm) Minimum (kg/h) Commonly used (kg/h) Maximum (kg/h)
25 0~1.14 0~78 0~204
40 0~2.92 0~194 0~525
50 0~4.57 0~310 0~822
80 0~11.7 0~775 0~2106
100 0~18.3 0~1292 0~3291
150 0~41.1 0~2584 0~7404
200 0~73.1 0~5168 0~13613
250 0~114 0~7752 0~20564
300 0~165 0~11162 0~29613
400 0~292 0~19845 0~52645
500 0~457 0~31008 0~82257
600 0~658 0~44652 0~118450
700 0~896 0~60775 0~161224
800 0~1170 0~79380 0~210578
900 0~1481 0~100465 0~266513
1000 0~1828 0~124032 0~329028
1200 0~2632 0~178606 0~473801
1500 0~4113 0~279072 0~740314
2000 0~7312 0~496128 0~1316113
The table shows the mass flow rate of air. Other gases can be referenced to the air for density selection.



Customer Service Hotline:13938765366

Company Telephone:13938765366



Company Address:North Section of Yuanxin Road, Xinxiang City, Henan Province


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