BURKERT 20044278 (Type 8745) is a mass flow controller (MFC) and mass flow meter (MFM) suitable for controlling the mass flow of large gas quantities. The device can be configured as an MFM or MFC according to demand. 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 family is available with electromagnetic or electromotive proportional valves, and supports communication via standard analogue signals, Industrial Ethernet, or Modbus RTU.

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
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
Degree of Protection	IP20

Approvals and Conformities

• North America (USA/Canada): Optional UL Listed 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 United States Pharmacopeial Convention (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 variable code NL02).

Measurement Principle

This sensor works as a hot-film anemometer in the CTA (Constant Temperature Anemometer) operational mode. 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

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.

Safety Information

• 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.
• 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 and vent or empty the lines.