BURKERT 20052011 Type 8745 Mass Flow Controller / Meter is designed for controlling the mass flow of large gas quantities, specifically configured for CO2 with a nominal flow rate of 50 kg/h. It features a 24 V DC supply voltage, G 1/2" internal thread port connection, and a 4-20 mA input/output signal. The Type 8745 can be configured as a Mass Flow Meter (MFM) or Mass Flow Controller (MFC). The thermal inline sensor located directly in the main gas stream achieves very fast response times with minimal pressure loss. As an actuator, a Bürkert direct-acting proportional valve guarantees high response sensitivity.

General Technical Data

Property	Description
Seal	FKM or EPDM (depending on gas)
Housing	PC (polycarbonate)
Base block	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 (Residual ripple ±2%, Voltage tolerance ±10%)
Operating medium	Neutral, pure gases (CO2 carbon dioxide for this configuration)
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
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
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
Measuring accuracy	±1.5% MV, ±0.3% FS
Repeatability	±0.1% 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.

Performance Data	Specification
Nominal flow range (QN)	20...2500 lN/min (N2)
Operating pressure	MFM: max. 22 bar
Measuring accuracy	± 2% MV, ± 0.5% FS
Repeatability	± 0.5% FS
Settling time (t95)	< 5 s

Approvals and Conformities

Conformity	Description
North America	Optional: UL Listed for the USA and Canada (UL 61010-1)
FDA	All wetted materials are compliant with the Code of Federal Regulations published by the FDA.
USP	All wetted materials are biocompatible according to the manufacturer's declaration.
EC 1935/2004	All wetted materials are compliant with EC Regulation 1935/2004/EC.
Oxygen	Optional: Suitability for oxygen.

Dimensions

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
G 1/2	15
NPT 1/2	14
G 3/4	16
NPT 3/4	15

Product Connections

Industrial Ethernet (Terminal strip, 3-pin)

Pin	Assignment
1	FE (functional earth)
2	DGND
3	24 V

Analogue (Terminal strip, 6-pin)

Pin	Assignment
1	24 V
2	GND
3	Set-point value input +
4	Set-point value input GND
5	Actual value output +
6	Actual value output GND

Modbus RTU (D-Sub plug, 9-pin)

Pin	Assignment
2	GND
3	24 V
6	RS-485-Y
7	RS-485-Z
8	RS-485-B
9	RS-485-A
Housing	Shielding

Performance Specifications

MFM Pressure Loss Diagram

Nominal Flow Rate of Typical Gases

Gas	Min. QN [l/min]	Max. QN [l/min]
Acetylene	20	320
Ammonia	8	1000
Argon	20	1600
Carbon dioxide	20	800 (1000 in some variants)
Air	20	2500
Methane	20	1200
Propane	20	200
Oxygen	20	2500
Nitrogen	20	2500

Derating Diagram for Electromotive Variants

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 heating current required to maintain a fixed excess temperature is a measure of the heat dissipation and represents the primary measured variable.

Safety Information

Electrostatically sensitive components

The device contains electronic components that are susceptible to the effects of electrostatic discharging (ESD). Do not touch electronic components when the supply voltage is connected.

Electric shock hazard

Touching live parts can result in severe electric shock. Before working on the device or system, switch off the power supply and secure it against reactivation.

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.