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gasQSTM flonic

Based on a microthermal CMOS sensor, in combination with a critical nozzle and two valves, the thermal conductivity, heat capacity and relative density of natural gas can be measured. From these quantities the device correlates different measured values.

This stand-alone device requires no carrier gases, is robust, compact and cost-effective. An integrated control output allows the setup of an additional automatic control measurement. The system is a complete proprietary development of Mems AG. Due to the complex knowledge of the physics, the individual components and their interaction, customer-specific applications can be implemented flexibly.

gasQS flonic hydrogen

Suitable for high hydrogen content

gasQS flonic measurement

Fast measurement

gasQS flonic integration

Simple to integrate

gasQS flonic reliable


gasQS flonic customizable


Prices and purchase orders

We would be happy to provide you with your personal offer in case of an inquiry.

Calibration check

gasQS™ flonic does not have specified due dates for calibration. Mems AG designed the device from the very beginning in such a way that reliable long-term behavior of the sensor is warranted. Our recommendation

Standard versions

For the specifications, please select the appropriate standard version below. If the characteristics do not fit your application, please contact us.

gasQSTM flonic

Measuring range1: Density (dn) 0.711 … 0.970 kg/m3
  Lower calorific value (Hi) 27.0 … 43.0 MJ/m3
  Higher calorific value (Hs) 30.2 … 47.2 MJ/m3
  Wobbe Index (WS) 39.6 … 56.5 MJ/m3
  Methane number AVL 60 … 100
Accuracy:Density (dn) ± 0.007 kg/m3
Lower calorific value (Hi) ± 1.0 MJ/m3
Higher calorific value (Hs) ± 1.0 MJ/m3
Wobbe Index (WS) ± 1.0 MJ/m3
Methane number AVL ± 3
Repeatability2:Density (dn) ± 0.003 kg/m3
Lower calorific value (Hi) ± 0.5 MJ/m3
Higher calorific value (Hs) ± 0.5 MJ/m3
Wobbe Index (WS) ± 0.5 MJ/m3
Methane number AVL ± 2


Measuring time:≤ 30 seconds
Measuring interval:continuous, programmable
Reaction time:T90 within 3 measuring intervals
Operating / storage temperature: - 10 … + 55 °C 3
ATEX device protection class:Ԑx II 2G Ex ib IIC T4 Gb (SEV 18 ATEX 0111 X)


Media:dry, neutral gases (10 μm filtering)
Input pressure range:+ 3.5 … + 5.0 bar relative
Permissible overload / burst pressure:+ 8.0 bar relative
Counterpressure on outlet side:≤ 400 mbar relative / ≤ 1.4 bar absolute
Gas consumption: ca. 0.1 ln/measuring interval


Output signal: Modbus-RTU (EIA-485 2-wire) 4
Supply voltage: +12.0 VDC ±10 % 5
Power requirement: ≤ 0.5 W


Gas connections: G 1/8 internal threads
Dimensions (l x w x h): 213 x 80 x 137 mm
Weight: 2.0 kg
Degree of protection: IP42

1 Reference conditions 0 °C, 25 °C, 1013.25 mbar absolute
Factory settings: MJ/m3, kg/m3 at reference conditions, further references and units are deposited
Further output values can be found in the order code or on request
2 Statistical scattering value with 2 sigma of 48 measuring points
3 Media and ambient temperature
4 Factory settings Modbus: 19200 bps, even parity bit + 1 stop bit, slave address: 0x01
5 When selecting the power supply unit, the voltage drop of the Zener barriers used must be compensated.

How often should one perform a calibration check on the gasQS™ flonic?

The gasQS™ flonic as a process instrument experiences wear from the conditions of the process in which it is installed. Temperature cycles, electronic component tolerance shift including the sensor chip and contamination build up over time on the sensor chip will all contribute to affecting the accuracy of the instrument. It should therefore regularly undergo, at a minimum, a calibration check if not a recalibration. But how often?
gasQS™ flonic does not have specified due dates for calibration. Mems AG designed the device from the very beginning in such a way that the above influences have the smallest possible effect on the long-term behavior of the sensor.
The inlet valve is protected by a double-mesh filter against the entry of dirt particles. A further filter shields the sonic nozzle from particles larger than its throat diameter. The chip sensor has passed its long-term test in several million passenger cars as a mass flow meter of the intake air, but also in household gas meters, over more than 6 years, no reduction in performance of the sensor could be detected. Due to the similar set-up as in the gas meter, no contamination of the chip, which would impair its function, is to be expected even in long-term operation with non-condensing gases. All electronic components meet the requirements of the strict standards of the automotive industry, so no premature aging effects should occur from this side either.
Mems suggests that gasQS™ flonic undergoes a calibration check once a year including a filter change at the device inlet. However, based on the application conditions, and perhaps company quality procedures, each customer must determine when they need to send in an instrument for recalibration. The easiest way to check is with methane of the quality ≥99.5%. The measured values can be compared with those of the initial test in the "Calibration Documentation" supplied with the instrument. The values for "Lambda Ratio", "Pressure Ratio" and "Flow Ratio" output in the registers 0x0020 to 0x0025 or 0x7020 to 0x7025 should all display the value 1 within half a percent. If this is not possible, Mems is happy to take on this task for its customers. ^top


The technical development is constantly progressing but the website does not update automatically. Therefore, technical changes to illustrations and information are reserved. We will be pleased to send you the latest version of the data sheet on request.