RK-100 Thermal Mass Flow meter

1. Brief Introduction to its Applications

The advanced technique of FTD Automation Instruments has been introduced to produce this flow meter measuring gas mass flow. Traditional flow meters need to adopt temperature and pressure compensation for measurement of fluid mass flow, whereas this flow meter can directly measure fluid mass flow without requiring temperature and pressure compensation. Its conspicuous features are as follows: direct trade settlement, no movable components, small pressure loss, wide range ratio, high accuracy, high reliability, simple installation and convenient operation. It is extensively used in the industries such as petroleum, chemical industry, medical industry, heat power plant and environmental protection etc.  

2. Operating Principle

The thermal gas mass flow meter employs thermal diffusion principle. The thermal diffusion technique is that of excellent performance and high reliability under severe conditions. The typical sensing elements include two thermal resistances (platina RTD); one is a velocity sensor and the other is a temperature sensor for automatic compensation for gas temperature variation. When the two RTDs are placed in medium, the velocity sensor is heated to a constant difference in temperature above ambient temperature, and the temperature sensor is used to respond to the medium temperature. If gas velocity increases, the heat quantity transmitted to the medium from the sensor will increase, so there is a need for more supply of power, whereas the power for electronic elements to heat RTD is corresponding with mass flow to a certain extent.   

3. Data    


±1% reading; ±0.5% full range


±0.5% of full range

Turn down ratio

Normal 100:1; it is decided by calibrated flow range

Upper Limit of Range

80 Nm/s (air,20,101.33kPa)

Lower Limit of Range

0.05Nm/s (air,20,101.33kPa)


Ø6~ Ø6000

Pressure Range

Negative Pressure, 0~1.0MPa,0~1.6MPa,0~2.0MPa,0~3.0MPa

Medium Temperature



All kinds pure gas or mixed gas with fixed percentage, gas with dust, sand or moisture, corrosive gas

Sensor Diameter

Ø3(standard), Ø4

Sensor Material


Probe Stem Diameter

Ø19(standard), Ø16, Ø12

Probe Stem Material


Power supply

24VDC/400mA or 220VAC/2W


4-20mA DC, max load 1000Ω;RS485


LED; four digits instantaneous flow , eight digits totalized flow


16 non-linearity correction


Remote type: transmitter + flow totalizer

Integral type: transmitter with integral totalzier

Connection type

In-line type and plug-in type


1-2 relay output,3A/220VAC,3A/30VAC,settable

Protection level


Explosive proof



5 years


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