BURKERT Type 8745 is a mass flow controller (MFC) and mass flow meter (MFM) 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 an electromagnetic proportional valve and with an electromotive 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

Property	Value
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)
Ambient Temperature	-10 °C to +50 °C (higher temperatures on request)
Degree of Protection	IP20
Installation Position	Horizontal or vertical

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 stand for highest measuring accuracy and repeatability with settling times resp. response times of a few hundred milliseconds.

• 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 (depends on medium and nominal valve size)
• Measuring accuracy: ±1.5% MV, ±0.3% FS
• Settling time (MFC) / Response time (MFM): < 500 ms
• Power consumption: Max. 4 W (as MFM); Max. 12.5...31.5 W (as MFC, depending on 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, reducing plant energy consumption dramatically. Without electrical power, the valve remains in its current position.

• 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 (MFC) / Response time (MFM): < 5 s
• Power consumption: Max. 4 W (as MFM); Max. 12 W (as MFC)

Approvals and Conformities

• North America (USA/Canada): Optional UL Listed (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

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

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

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

Derating Diagram for Electromotive Variants

Product Accessories

Bürkert Communicator Software

The Bürkert Communicator is the most important software component of the EDIP (Efficient Device Integration Platform). Various features of this universal tool simplify the configuration and parametrisation of devices equipped with a digital CANopen-based interface. The integrated graphical programming environment enables the creation of decentralised sub-system control functions.

Configuration Management for Easy Device Replacement

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. The memory card is available as an accessory and must be ordered separately.

Web Server for Industrial Ethernet Variant

All Industrial Ethernet-based devices (except for the EtherCAT® protocol) from software version A.13.00.00 onwards have an integrated web server. The server can be accessed via a web browser when entering the device’s IP address (factory setting IP 192.168.1.100).

Safety Information

Electric shock due to electrical components

Touching live parts can result in severe electric shock. This can lead to serious personal injury or death.

• Before working on the device or system, switch off the power supply. Secure it against reactivation.
• Observe any applicable accident prevention and safety regulations for electrical devices.

Medium under pressure

Medium under pressure can seriously injure people. In the event of overpressure or pressure surges, the device or lines can burst. Pneumatic lines that are defective or not securely fastened can come loose and swing around.

• Before working on the device or system, switch off the pressure. Vent or empty the lines.
• Adhere to the permitted pressure ranges of the medium.

Hot surfaces and fire hazard

The surface of the device can become hot with fast-switching actuators or with hot media.

• Wear suitable protective gloves.
• Keep highly flammable substances and media away from the device.

Electrostatically sensitive components

The device contains electronic components that are susceptible to the effects of electrostatic discharging (ESD). Meet the requirements specified by EN 61340-5-1 to minimize or avoid the possibility of damage caused by a sudden electrostatic discharge.