Category: Thermal Gas Mass Flowmeter
OBLMF SERIES THERMAL GAS MASS FLOWMETER
Product Related Description
The thermal gas mass flowmeter is designed based on the principle of thermal diffusion. This instrument accurately measures gas by using the constant temperature difference method. It has the advantages of small size, high degree of digitalization, easy installation and accurate measurement.
Main features
·A true mass flow meter that does not require temperature and pressure compensation for gas flow measurement, making measurement convenient and accurate. The mass flow rate or standard volume flow rate of the gas can be obtained.
·Wide range ratio, can measure gases with flow rates as high as 120Nm/S and as low as 0.1Nm/s, and can be used for gas leak detection.
·Good seismic resistance and long service life. The sensor has no moving parts and pressure sensing parts, and is not affected by vibration on measurement accuracy.
·Easy to install and maintain. If site conditions permit, non-stop installation and maintenance can be achieved. (requires special customization)
·Digital design. Overall digital circuit measurement, accurate measurement and easy maintenance.
·Using RS-485 communication or HART communication to realize factory automation and integration.
working principle
The sensor part consists of two reference-level platinum resistance temperature sensors. When the instrument is working, one sensor continuously measures the medium temperature T1; the other sensor is self-heated to a temperature higher than the medium temperature T2. It is used to sense the fluid flow rate and is called a speed sensor. The temperature ΔT=T2-T1, T2>T1. When fluid flows through, the gas molecules collide with the sensor and take away the heat of T2, causing the temperature of T2 to drop. If ΔT remains unchanged, the power supply current of T2 must be increased. The faster the gas flows, the more heat is taken away. There is a fixed functional relationship between the gas flow rate and the increased heat. This is the principle of constant temperature difference.
Among them - fluid specific gravity (related to density)
V-flow rate
K-balance coefficient
Q-Heating amount (related to specific heat and structure)
ΔT-temperature difference
Technical performance indicators
Since the sensor temperature is always about 30°C higher than the medium (environment) temperature, the thermal gas flowmeter does not require temperature compensation in principle. The applicable medium temperature range of the thermal gas mass flow meter is -40~450℃.
(1) The specific gravity and density of the fluid in the formula are related
(2) Among them
Pg-Media density under working condition volume (kg/m3)
Pn-Media density under standard conditions (101.325kpa, 2℃) (kg/m3)
P-working pressure (kpa)
T-working temperature (℃)
It can be seen from equations (1) and (2) that the functional relationship between flow rate and operating pressure, gas density and operating temperature has been determined.
The constant temperature differential thermal gas mass flow meter is not only not affected by temperature, but also is not affected by pressure. The thermal gas mass flow meter is a true direct mass flow meter, and the user does not need to correct the pressure and temperature.
Technical indicators and parameters of thermal gas mass flowmeter
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Structural form |
Insertable type |
Pipeline type |
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Measuring medium |
Common steady-state gases (such as acetylene, boron trichloride and other unstable media cannot be measured) |
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Pipe diameter range |
DN50~4000mm |
DN6-2000mm |
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Flow velocity range |
0.1-100Nm/s |
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Accuracy |
±1~2.5% |
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Working temperature |
Sensor:-40 to +450℃ Converter:-20 to +45℃ |
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Work pressure |
The medium pressure is ≤2.5MPa |
The medium pressure is ≤1.6MPa |
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Power supply |
The power of DC 24V should be greater than 18W |
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Response speed |
1s |
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Output signal |
4-20mA(photoelectric isolation, maximum load 500 ohms), RS-485(photoelectric isolation) |
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Alarm |
1-2 normally open contacts |
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Supply type |
Integrated structure |
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Pipe material |
Carbon steel, Stainless steel,Plastic,etc |
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On-site display |
Four lines of Chinese characters, LCD display |
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Display content |
Mass flow rate, volume flow rate under standard conditions, cumulative flow rate, standard time, cumulative operating time, standard flow velocity, etc |
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Protection grade |
IP65 |
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Sensor material |
Stainless steel |
Stainless steel, Carbon steel |
Keywords: OBLMF SERIES THERMAL GAS MASS FLOWMETER
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