BURKERT Type 8745 Mass Flow Controller (MFC) / Mass Flow Meter (MFM) is suitable for controlling the mass flow of large gas quantities. Type 8745 can be configured as 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. As an MFC, type 8745 is available in two variants: with electromagnetic proportional valve and with electromechanical proportional valve. In addition to an analogue and an industrial ethernet variant, a Modbus RTU variant is also available.

• Nominal flow range from 20 lN/min to 2500 lN/min (re. nitrogen)
• High accuracy and repeatability
• Communication via standard signals or Industrial Ethernet
• Electromagnetic and electromotoric valve actuation available
• Easy device exchange due to configuration memory

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 (sensor)	Stainless steel 1.4404/316L, Al₂O₃, PPS GF40, epoxy resin, silicon, silicon nitride
Electrical data
Operating voltage	24 V DC
Residual ripple	±2%
Voltage tolerance	±10%
Electrical connection
Analogue variant	D-Sub plug, 9-pin or terminal strip, 6-pin
Industrial Ethernet variant	2 x RJ45 socket (Switch)
Modbus RTU variant	D-Sub plug, 9-pin
Medium data
Operating medium	Neutral, pure gases (others on request)
Calibration medium	Operating medium or air
Medium temperature	-10 °C to +70 °C (-10 °C to +60 °C with oxygen)
Product connections
Analogue interface	4...20 mA, 0...20 mA, 0...10 V or 0...5 V Input impedance: >20 kΩ (voltage) or <300 Ω (current) Maximum current: 10 mA (voltage output) Maximum load: 400 Ω (current output)
Digital communication interface	Modbus RS-485/RTU list 0 and list 1, 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
Environment and installation
Installation position	Horizontal or vertical
Storage temperature	-10 °C to +70 °C
Relative air humidity	Max. 95 % at +55 °C, non-condensing
Degree of protection	IP20
Ambient temperature	-10 °C to +50 °C (higher temperatures on request)

Note

When using an electromotive proportional valve, the minimum medium temperature is 0 °C.

Variant with Electromagnetic Proportional Valve

Type 8745 can be configured as MFM or MFC as required. The MFC variant uses direct-acting proportional valves of the 287x series. These electromagnetic proportional valves are normally closed and stand for highest measuring accuracy and repeatability with settling times resp. response times of a few hundred milliseconds.

Product properties
Total weight	Approx. 1800 g (aluminium, 16 W valve) Approx. 3100 g (stainless steel 1.4404/316L, 16 W valve)
LED display	RGB-LED based on NAMUR NE107
Actuator (proportional valve)
Valve position	Normally closed
Nominal diameter	0.8...12 mm
Kvs value range	0.02...2.5 m³/h
Performance data
Nominal flow range (QN)	MFC: 20...1500 lN/min (N₂) MFM: ≤ 2500 lN/min (N₂)
Operating pressure	MFM: max. 25 bar MFC: max. 25 bar (the maximum operating pressure depends on medium and nominal valve size)
Measuring accuracy	±1.5% MV ±0.3% FS (under calibration conditions and after <1 min warm-up time)
Repeatability	±0.1% FS
Turndown ratio	1:50
Settling time (MFC)/Response time (MFM) (t95)	<500 ms
Electrical data
Power consumption	Max. 4 W (as MFM) Max. 12.5...31.5 W (as MFC, depending on proportional valve type)

Variant with Electromotive Proportional Valve

Type 8745 with 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. This key feature can reduce the energy consumption of a plant dramatically. Without electrical power the valve remains in its current position.

Product properties
Total weight	Approx. 1670 g (aluminium, valve Type 3280) Approx. 2940 g (stainless steel 1.4404/316L, valve Type 3280)
LED display	With MFM: RGB LED according to NAMUR NE107 With valve: RGB LED to indicate valve opening
Actuator (proportional valve)
Valve position	Normally closed
Nominal diameter	2...20 mm
Kvs value range	0.5...7.8 m³/h
Performance data
Nominal flow range (QN)	20...2500 lN/min (N₂)
Operating pressure	MFM: max. 22 bar For MFCs, the maximum operating pressure depends on the medium and nominal valve size
Measuring accuracy	± 2% MV ± 0.5% FS (under calibration conditions and after <1 min warm-up time)
Repeatability	± 0.5% FS
Turndown ratio	1:50
Settling time (MFC)/Response time (MFM) (t95)	<5 s
Electrical data
Power consumption	Max. 4 W (as MFM) Max. 12 W (as MFC)

Approvals and Conformities

• 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.
• 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 manufacturer's declaration (valid for variable code PL04).
• EC Regulation 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 the variable code NL02).

Dimensions

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 Connections

Industrial Ethernet

Pin	Assignment
1	TX +
2	TX -
3	RX +
4	Not connected
5	Not connected
6	RX -
7	Not connected
8	Not connected
Housing	Shielding

Analogue

Pin	Assignment
1	Digital input
2	GND (for supply voltage and digital input)
3	24 V
4	Relay, normally closed contact
5	Relay, reference contact
6	Set-point value input +
7	Set-point value input GND
8	Actual value output
9	Actual value output GND
Housing	Shielding

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

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.

Nominal Flow Rate of Typical Gases

Note

All values refer to 1013.25 mbar 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	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

Derating Diagram for Electromotive Variants

Product Operation

Measurement Principle

This sensor works as a hot-film anemometer in the so called CTA operational mode (Constant Temperature Anemometer). 2 resistors with a precisely specified temperature coefficient located directly in the media flow and 3 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.

Adequate flow conditioning within the MFC and calibration with high-quality flow standards ensure that the amount of gas flowing through per time unit can be derived from the primary signal with a high degree of accuracy.

Safety Information

Warnings and basic safety information

• Electrostatically sensitive components: The device contains electronic components that are susceptible to the effects of electrostatic discharging (ESD). Do not touch electronic components when the supply voltage is connected.
• Electric shock: Touching live parts can result in severe electric shock. Before working on the device or system, switch off the power supply.
• Medium under pressure: Medium under pressure can seriously injure people. Before working on the device or system, switch off the pressure. Vent or empty the lines.
• Hot surfaces: The surface of the device can become hot with fast-switching actuators or with hot media. Wear suitable protective gloves.