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.

Key Features

• 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	Value
Material
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
Electrical data
Operating voltage	24 V DC
Residual ripple	±2%
Voltage tolerance	±10%
Medium data
Operating medium	Neutral, pure gases (others on request)
Calibration medium	Operating medium or air
Medium temperature	-10 °C to +70 °C (-10 °C to +60 °C with oxygen)
Environment and installation
Installation position	Horizontal or vertical
Degree of protection	IP20

Variant with Electromagnetic Proportional Valve

Type 8745 can be configured as MFM or MFC as required. 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.

Performance Data	Value
Nominal flow range (QN)	MFC: 20 to 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
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. Without electrical power the valve remains in its current position.

Performance Data	Value
Nominal flow range (QN)	20 to 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

Communication Interfaces

Industrial Ethernet (Terminal strip, 3-pin)

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

Analogue (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

Modbus RTU

Pin	Assignment
6	RS-485-Y
7	RS-485-Z
8	RS-485-B
9	RS-485-A
Housing	Shielding

Approvals and Conformities

Approvals

• North America: Optional UL Listed for the USA and Canada (UL 61010-1).
• Foods and beverages/Hygiene: FDA (Code of Federal Regulations), USP (United States Pharmacopeial Convention), and EC Regulation 1935/2004 compliant variants available.
• Oxygen: Optional suitability for gaseous oxygen.

Measurement Principle

This sensor works as a hot-film anemometer in the so called CTA operational mode (Constant Temperature Anemometer). 2 resistors with a precisely specified temperature coefficient located directly in the media flow and 3 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

• 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. Before working on the device or system, switch off the pressure. Vent or empty the lines.