Principle
Thermal gas mass flow meter is designed on the basis of thermal dispersion, and adopts method of constant differential temperature to measuring gas flow. It has advantages of small size, easy installation, high reliability and high accuracy, etc.
The meter contains two platinum resistance temperature sensors. The thermal principle operates by monitoring the cooling effect of a gas stream as it passes over a heated sensor. Gas flowing through the sensing section passes over two sensors one of which is used conventionally as a temperature sensor, whilst the other is used as a heater. The temperature sensor monitors the actal process values whilst the heater is maintained at a constant differential temperature above this by varying the power consumed by the sensor. The greater the gas velocity, the greater the cooling effect and power required to maintain the differential temperature. The measured heater power is therefore a measure of the gas mass flow rate.
Feature
♦ Measuring the mass flow or volume flow of gas
♦ Do not need to do temperature and pressure compensation in principle with accurate measurement and easy operation.
♦ Wide range: 0.5Nm/s~100Nm/s for gas. The meter also can be used for gas leak detection
♦ Good vibration resistance and long service life. No moving parts and pressure sensor in transducer, no vibration influence on the measurement accuracy.
♦ Easy installation and maintenance. If the conditions on site are permissible, the meter can achieve a hot-tapped installation and maintenance. (Special order of custom-made)
♦ Digital design, high accuracy and stability
♦ Configuring with RS485 or HART interface to realize factory automation and integration
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Thermal Mass Flow Meter Specification
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Size
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DN80-DN4000 (Insertion), DN10-DN2000 (Pipe)
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Medium
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Gas (except acetylene)
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Velocity
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0.5~100 Nm/s (20℃、101.33KPA)
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Accuracy
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±1% of read (Pipe), ±2.5% of read (Insertion)
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Working Temperature
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-40℃～+220℃ (Sensor), -20℃～+45℃ (Transmitter)
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Working Pressure
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Insertion ≤2.5 MPa, Pipe ≤4.0 MPa
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Response
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1s
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Signal Output
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Pulse,4-20mA (optoelectronic isolation, maximum load 500Ω)
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Communication
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RS485 (optoelectronic isolation), HART
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Pipe Material
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Carbon Steel, Stainless Steel
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Sensor Housing Material
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SS304 or SS316
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Sensor Type
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Standard Insertion, Hot-tapped Insertion,Flanged
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Alarm Output
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1-2 line Relay, Normally Open state, 10A/220V/AC or 5A/30V/DC
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Protection Grade
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IP65
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Sensor Material
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Stainless steel,Carbon Steel,
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Power Supply
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Compact type: 24VDC or 220VAC, Power consumption ≤18W
Remote type: 220VAC, Power consumption ≤19W
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Display
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4 lines LCD,Mass flow, Volume flow in standard condition, Flow totalizer, Date and Time, Working time, and Velocity, etc
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Thermal Mass Flow Meter Selection Model
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Model
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QTMF
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X
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X
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X
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X
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X
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X
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X
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Caliber
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DN10-DN4000
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Structure
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Compact
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C
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Remote
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R
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Senor type
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Insertion
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I
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Flange
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F
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Clamp
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C
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Screw/Thread
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S
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Material
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SS304
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304
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SS316
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316
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Pressure
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1.6Mpa
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16
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2.5Mpa
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25
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4.0Mpa
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40
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Temperature
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-40-200℃
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T1
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-40-450℃
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T2
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Power Supply
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AC85~250V
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AC
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DC20V~36V
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DC
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Signal Output
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4-20mA+Pulse+RS485
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RS
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4-20mA+Pulse+HART
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HT
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