BURKERT 339597 Type 8745 is a mass flow controller (MFC) suitable for controlling the mass flow of large gas quantities. 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. This specific model is configured for CH4 methane with a nominal flow rate of 80 Nl/min, utilizing a Type 2873 electromagnetic proportional valve and a 1/2" NPT internal thread connection.

General Technical Data

Property	Description
Housing Material	PC (polycarbonate)
Base Block Material	Stainless steel 1.4404/316L
Seal Material	FKM (Fluor rubber)
Operating Voltage	24 V DC (Voltage tolerance ±10%, Residual ripple ±2%)
Electrical Connection	D-Sub plug, 9-pin (Analogue variant)
Operating Medium	CH4 methane (Real gas calibration)
Medium Temperature	-10 °C to +70 °C
Port Connection	NPT 1/2" Internal thread
Analogue Interface	4...20 mA (Input/Output)
Degree of Protection	IP20

Electromagnetic Proportional Valve (Type 2873)

This MFC variant uses a direct-acting proportional valve of the 287x series. The electromagnetic proportional valve is normally closed and stands for the highest measuring accuracy and repeatability with settling times of a few hundred milliseconds.

Performance Data	Value
Valve Position	Normally closed
Nominal Seat Diameter	2 mm (5/64")
Operating Pressure	Max. 5 bar
Measuring Accuracy	±1.5% MV, ±0.3% FS (under calibration conditions)
Repeatability	±0.1% FS
Turndown Ratio	1:50
Settling Time (t95)	< 500 ms

Dimensions

Large nominal flow rates, with internal thread

Thread (A)	Thread depth [mm]
NPT 1/2	14

Variant with electromagnetic proportional valve MFC with valve Type 2873

Product Connections

Analogue Interface (D-Sub plug, 9-pin)

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

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.

Safety Information

• 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 or empty the lines.
• Electric shock: Touching live parts can result in severe electric shock. Before working on the device or system, switch off the power supply.