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. Type 8741 can be configured as an MFM or an MFC according to demand. Furthermore, a Modbus RTU variant is also available. 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.

General Technical Data

Product properties
Material
Seal	FKM or EPDM (depending on gas)
Housing	PC (polycarbonate)
Base block	Aluminium or stainless steel 1.4404/316L
Wetted parts	Stainless steel 1.4310/302, 1.4113/434, 1.4305/303
Total weight	Approx. 500 g (aluminium base block)
Performance data
Nominal flow range ($Q_N$)	10 ml...160 lN/min ($N_2$)
Operating pressure	MFM: max. 25 bar MFC: max. 25 bar
Measuring accuracy	±0.8% MV ±0.3% FS
Repeatability	±0.1% FS
Turndown ratio	1:50, optionally 1:100
Settling time (MFC) / Response time (MFM) ($t_{95}$)	<300 ms
Electrical data
Operating voltage	24 V DC
Power consumption	1...3 W (as MFM) Max. 3...19.5 W (as MFC)
Medium data
Operating medium	Neutral, pure gases
Medium temperature	-10 °C...+70 °C (-10 °C...+60 °C with oxygen)

Approvals and Conformities

• North America (USA/Canada): Optional UL Listed (UL 61010-1, CAN/CSA-C22.2 No. 61010-1)
• Foods and beverages/Hygiene: FDA (Code of Federal Regulations), USP (United States Pharmacopeial Convention) Class VI, EC Regulation 1935/2004
• Oxygen: Optional suitability for gaseous oxygen

Product Connections

Modbus RTU

Pin	Assignment
1	Not connected
2	GND
3	24 V
4	Not connected
5	Not connected
6	RS-485-Y
7	RS-485-Z
8	RS-485-B
9	RS-485-A
Housing	Shielding

Performance Specifications

Nominal Flow Rate of Typical Gases

(Values refer to 1.013 bar abs and 273.15 K)

Gas	Min. $Q_N$ [l/min]	Max. $Q_N$ [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

Product Operation

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.

Configuration Management

If a device needs to be replaced, the memory card can be removed from the defective device and inserted into the new device. This transfers all data from the device to be replaced to the new device.