BURKERT Type 8741 mass flow controller (MFC) and mass flow meter (MFM) for gases is suitable for a variety of applications and is available with Industrial Ethernet, analogue, or fieldbus interfaces. The variant with CANopen-based Bürkert Systembus (büS) is suitable for integration into existing CANopen networks or—in combination with the Type ME43 fieldbus gateway—for integration into all common industry standards for Industrial Ethernet and/or fieldbus. The latter option is tailor-made for applications with many control loops, allowing up to 32 MFCs or MFMs to be connected to one fieldbus gateway.

Type 8741 can be configured as an MFM or an MFC according to demand. Furthermore, a Modbus RTU variant is also available. Optionally, up to four calibration curves can be stored in the device. The thermal MEMS sensor is located directly in the gas stream and therefore achieves very fast response times. As the actuator, a Bürkert direct-acting proportional valve guarantees high response sensitivity.

Key Features

• Nominal flow range from 0.010 lN/min to 160 lN/min (re. nitrogen)
• High accuracy in measurement and repeat accuracy
• Very fast response times
• Easy device exchange due to configuration memory
• Optional: USP Class VI, FDA, EC 1935 compliant

General Technical Data

Property	Description
Seal Material	FKM or EPDM (depending on gas)
Housing Material	PC (polycarbonate)
Base Block Material	Aluminium or stainless steel 1.4404/316L
Wetted Parts	Stainless steel 1.4310/302, 1.4113/434, 1.4305/303
Operating Pressure	MFM: max. 25 bar; MFC: max. 25 bar (depends on medium and nominal valve size)
Measuring Accuracy	±0.8% MV ±0.3% FS (under calibration conditions and after warm-up time)
Repeatability	±0.1% FS
Turndown Ratio	1:50, optionally 1:100
Settling/Response Time	< 300 ms
Operating Voltage	24 V DC (±10% tolerance, ±2% residual ripple)
Power Consumption	1...3 W (as MFM); Max. 3...19.5 W (as MFC, depending on proportional valve)
Operating Medium	Neutral, pure gases (others on request)
Medium Temperature	-10 °C...+70 °C (-10 °C...+60 °C with oxygen)
Ambient Temperature	-10 °C...+50 °C
Degree of Protection	IP20

Approvals and Conformities

Conformity Standards

In accordance with the Declaration of Conformity, the product is compliant with the EU Directives. The applied standards which are used to demonstrate compliance are listed in the EU-Type Examination Certificate and/or the EU Declaration of Conformity.

• North America (USA/Canada): Optional UL Listed for the USA and Canada according to UL 61010-1 and CAN/CSA-C22.2 No. 61010-1.
• Foods and Beverages / Hygiene:
  • FDA – Code of Federal Regulations (valid for variable code PL02, PL03)
  • United States Pharmacopeial Convention (USP) Class VI (valid for variable code PL04)
  • EC Regulation 1935/2004 of the European Parliament and of the Council (valid for variable code PL01, PL02)
• Oxygen: Optional suitability for use with gaseous oxygen (valid for the variable code NL02).

Performance Specifications

Nominal Flow Rate of Typical Gases

Note

All values refer to 1.013 bar abs and 273.15 K (0 °C) (Index N). Other gases and gas mixtures are possible on request.

Gas	Min. QN [l/min]	Max. QN [l/min]
Acetylene	0.01	65
Helium	0.01	1000
Carbon dioxide	0.02	80
Air	0.01	160
Methane	0.01	160
Oxygen	0.01	160
Nitrogen	0.01	160
Hydrogen	0.01	1000
Propane	0.03	44

MFM Pressure Loss Diagram

The diagram shows an example of the pressure loss curves with air flowing through. To determine the pressure loss of other gases, the corresponding air equivalent must first be calculated and the base block used for the other gas must be taken into account.

Measurement Principle

The measured values are recorded in a secondary channel. A laminar flow element in the main channel creates a slight pressure drop. A part of the gas flow is thereby directed into the secondary channel. The sensor located there records the mass flow as a temperature difference. The measurement is performed in a specially shaped flow channel whose wall contains a silicon chip with an etched membrane. A heating resistor and 2 temperature sensors, one upstream and one downstream, are attached on this membrane.

If the heating resistor is fed with a constant voltage, the differential voltage of the temperature sensors indicates the flow rate of the gas flowing over the chip.