BURKERT Type 8745 (SKU 20093881) 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 (Type 2875) guarantees high response sensitivity. This specific model is configured for N2 nitrogen with a nominal flow rate of 200 Nl/min, featuring a G 1/4" internal thread and a 4-20 mA analogue interface.

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)
Electrical Connection	D-Sub plug, 9-pin (Analogue variant)
Operating Medium	Neutral, pure gases (N2 nitrogen for SKU 20093881)
Medium Temperature	-10 °C to +70 °C (-10 °C to +60 °C with oxygen)
Analogue Interface	4...20 mA (Input impedance: <300 Ω for current; Maximum load: 400 Ω for current output)
Installation Position	Horizontal or vertical
Degree of Protection	IP20

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 of a few hundred milliseconds.

Performance Data	Specification
Valve Position	Normally closed
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 (t95)	<500 ms

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.
• Foods and Beverages/Hygiene: Wetted materials are compliant with FDA Code of Federal Regulations, USP (biocompatible), and EC Regulation 1935/2004/EC depending on the variable code.
• Oxygen: Optional suitability for use with gaseous oxygen.

Dimensions

MFC with valve Type 2875 (Variant with base block 00 or A1 for small nominal flow rates)

INFO

Note: Dimensions in mm.

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

Product Connections

Analogue Connection (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

Performance Specifications

Nominal flow rate of typical gases

INFO

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

Gas	Min. Q_N [l/min]	Max. Q_N [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

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.

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). 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. 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.