Bürkert Type 8745 (SKU 20133853) is a mass flow controller (MFC) or mass flow meter (MFM) suitable for controlling the mass flow of large gas quantities. This specific configuration is designed for NH3 ammonia with a nominal flow rate of 6000 SLPH, featuring a G 1/4" internal thread and PROFINET communication. 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.

Type 8745 can be configured as MFM or MFC according to demand. Optionally, up to four calibration curves can be stored in the device. It is available in two main variants: with an electromagnetic proportional valve and with an electromotive proportional valve.

General Technical Data

Product Properties	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 (±10% voltage tolerance, ±2% residual ripple)
Digital communication	PROFINET (SKU 20133853), EtherCAT®, EtherNet/IP, Modbus TCP, Modbus RTU
Operating medium	Neutral, pure gases (NH3 ammonia for SKU 20133853)
Medium temperature	-10 °C to +70 °C (-10 °C to +60 °C with oxygen)
Installation position	Horizontal or vertical
Degree of protection	IP20

Configuration Management

If a device needs to be replaced, the memory card can be removed from the defective device and inserted into the new device. This transfers all data from the device to be replaced to the new device, provided both have the same article number.

Actuator Variants

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.

• Nominal flow range (QN): MFC: 20...1500 lN/min (N2); MFM: ≤ 2500 lN/min (N2)
• Operating pressure: Max. 25 bar (depends on medium and nominal valve size)
• 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 an 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, which can reduce the energy consumption of a plant dramatically.

• Nominal flow range (QN): 20...2500 lN/min (N2)
• Operating pressure: MFM: max. 22 bar; MFC depends on medium and valve size
• Measuring accuracy: ± 2% MV, ± 0.5% FS
• Turndown ratio: 1:50
• Settling time (t95): < 5 s

Approvals and Conformities

• 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 compliance available for specific wetted materials.
• Oxygen: Optional suitability for use with gaseous oxygen.

Performance Specifications

Nominal Flow Rate of Typical Gases

Note: 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 Diagram

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.

Derating Diagram for Electromotive Variants

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.

Bürkert Communicator Software

The Bürkert Communicator is the most important software component of the EDIP (Efficient Device Integration Platform). It simplifies the configuration and parametrisation of devices, providing a complete overview of cyclic process values and acyclic diagnostic data. Connection to a PC is established via a USB-büS interface set.

Safety Information

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. Always switch off the power supply and pressure before working on the device or system.