BURKERT Type 8745 mass flow controller (MFC) and mass flow meter (MFM) is designed for controlling the mass flow of large gas quantities. It can be configured as an MFM or MFC according to demand. Optionally, up to four calibration curves can be stored in the device. The thermal inline sensor located directly in the main gas stream achieves very fast response times with minimal pressure loss. As the actuator, a Bürkert direct-acting proportional valve guarantees high response sensitivity. The Type 8745 is available with either an electromagnetic proportional valve or an electromotive proportional valve, and supports analogue, Industrial Ethernet, and Modbus RTU communication interfaces.

General Technical Data

Feature	Specification
Seal Material	FKM or EPDM (depending on gas)
Housing Material	PC (polycarbonate)
Base Block Material	Aluminium or stainless steel 1.4404/316L
Wetted Parts (Sensor)	Stainless steel 1.4404/316L, Al₂O₃, PPS GF40, epoxy resin, silicon, silicon nitride
Operating Voltage	24 V DC (±10% voltage tolerance, ±2% residual ripple)
Operating Medium	Neutral, pure gases (others on request)
Medium Temperature	-10 °C to +70 °C (-10 °C to +60 °C with oxygen)
Analogue Interface	4...20 mA, 0...20 mA, 0...10 V or 0...5 V
Digital Interface	Modbus RS-485/RTU, Industrial Ethernet (EtherCAT®, EtherNet/IP, Modbus TCP, PROFINET)
Port Connection	G 1/4", NPT 1/4, 3/8, 1/2, 3/4, 1, sub-base, clamp connection
Degree of Protection	IP20

Note on Electromotive Valves

When using the electromotive proportional valve, the minimum medium temperature is 0 °C. The device additionally includes a PEEK valve seat seal (Type 3280 DN 4) or an Al₂O₃ valve seat seal (Type 3285).

Actuator Variants

Variant with Electromagnetic Proportional Valve

The MFC variant uses direct-acting proportional valves of the 287x series. These electromagnetic proportional valves are normally closed and provide the highest measuring accuracy and repeatability with settling times of a few hundred milliseconds.

• Nominal flow range (QN): MFC: 20...1500 lN/min (N₂); MFM: ≤ 2500 lN/min (N₂)
• Operating pressure: Max. 25 bar (depends on medium and nominal valve size)
• Measuring accuracy: ±1.5% MV ±0.3% FS
• Settling time (t95): < 500 ms
• Power consumption: Max. 4 W (as MFM); Max. 12.5...31.5 W (as MFC)

Variant with Electromotive Proportional Valve

Type 8745 with an electromotive proportional valve is especially suitable for applications with high inlet pressures of up to 22 bar or high flow rates at a low pressure drop. The motor’s power consumption to hold a specific opening position is nearly zero, drastically reducing plant energy consumption.

• Nominal flow range (QN): 20...2500 lN/min (N₂)
• Operating pressure: MFM: max. 22 bar; MFC: depends on medium and nominal valve size
• Measuring accuracy: ± 2% MV ± 0.5% FS
• Settling time (t95): < 5 s
• Power consumption: Max. 4 W (as MFM); Max. 12 W (as MFC)

Approvals and Conformities

• North America: Optional UL Listed for the USA and Canada (UL 61010-1, CAN/CSA-C22.2 No. 61010-1).
• FDA: All wetted materials are compliant with the Code of Federal Regulations published by the FDA (valid for variable code PL02, PL03).
• USP: All wetted materials are biocompatible according to the United States Pharmacopeial Convention (valid for variable code PL04).
• EC 1935/2004: All wetted materials are compliant with EC Regulation 1935/2004/EC (valid for variable code PL01, PL02).
• Oxygen: Optional suitability for use with gaseous oxygen (valid for variable code NL02).

Measurement Principle

This sensor works as a hot-film anemometer in the CTA operational mode (Constant Temperature Anemometer). Two resistors with a precisely specified temperature coefficient located directly in the media flow and three further resistors are connected to form a measuring bridge. The first resistor in the gas flow measures the fluid temperature, while the second, low-value resistor is always heated just enough to keep it at a fixed, specified excess temperature with respect to the fluid temperature. The heating current required for this is a measure of the heat dissipation and represents the primary measured variable.

Performance Specifications

Nominal Flow Rate of Typical Gases

All values refer to 1013.25 mbar abs and 273.15 K (0 °C).

Gas	Min. QN [l/min]	Max. QN [l/min]
Acetylene	20	320 (from 65 l/min with air calibration)
Ammonia	8	1000
Argon	20	1600
Carbon dioxide	20	800
Air	20	2500
Methane	20	1200
Propane	20	200
Oxygen	20	2500
Nitrogen	20	2500

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.

Threaded Variant Connections

Small nominal flow rates, with internal thread:

Thread (A)	Thread depth [mm]
G 1/4	12
NPT 1/4	11
G 3/8	12
NPT 3/8	11
G 1/2	15
NPT 1/2	14
G 3/4	16
NPT 3/4	15

Large nominal flow rates, with internal thread:

Thread (A)	Thread depth [mm]
G 1/2	15
NPT 1/2	14
G 3/4	16
NPT 3/4	15
G 1	18
NPT 1	16.8

Product Accessories

• Bürkert Communicator Software: The most important software component of the EDIP (Efficient Device Integration Platform). It simplifies configuration, parametrisation, and diagnosis of devices equipped with a digital CANopen-based interface.
• 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, transferring all data automatically.
• Web Server: All Industrial Ethernet-based devices (except EtherCAT®) from software version A.13.00.00 onwards have an integrated web server accessible via a web browser.

Safety Information

• Electrostatically sensitive components: The device contains electronic components susceptible to electrostatic discharge (ESD). Meet the requirements of EN 61340-5-1.
• Electric shock: Touching live parts can result in severe electric shock. Switch off the power supply before working on the device.
• Medium under pressure: In the event of overpressure or pressure surges, the device or lines can burst. Switch off the pressure and vent lines before maintenance.