Burkert Type 8745 Mass Flow Controller (MFC) and 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 an electromagnetic proportional valve and with an 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

Property	Description
Seal Material	FKM or EPDM (depending on gas)
Housing Material	PC (polycarbonate)
Base block Material	Aluminium or stainless steel 1.4404/316L
Operating voltage	24 V DC (±10% voltage tolerance)
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 communication	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

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: Max. 25 bar
• Measuring accuracy: ±1.5% MV, ±0.3% FS
• Turndown ratio: 1:50
• Settling time (t95): < 500 ms

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, which can reduce the energy consumption of a plant dramatically.

• Nominal flow range (QN): 20...2500 lN/min (N2)
• Operating pressure: MFM: max. 22 bar
• Measuring accuracy: ± 2% MV, ± 0.5% FS
• Turndown ratio: 1:50
• Settling time (t95): < 5 s

Performance Specifications

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

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.

Product Operation

Measurement Principle

This sensor works as a hot-film anemometer in the so-called 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.

Approvals and Conformities

• North America: Optional UL Listed for the USA and Canada (UL 61010-1).
• Foods and Beverages/Hygiene: FDA compliance, USP Class VI, and EC Regulation 1935/2004 available depending on variable codes.
• Oxygen: Optional suitability for use with gaseous oxygen.

Safety Information

• Electrostatically sensitive components: The device contains electronic components that are susceptible to the effects of electrostatic discharging (ESD).
• 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. In the event of overpressure or pressure surges, the device or lines can burst. Before working on the device or system, switch off the pressure and vent the lines.