BURKERT 20092146 (Type 8745) is a thermal mass flow controller configured for high-flow gas regulation up to 350 Nl/min of nitrogen (N2). Operating on an inline Constant Temperature Anemometer (CTA) thermal sensor principle directly in the main stream, the instrument executes closed-loop flow control with minimal pressure loss. Actuation is delivered by an integrated Bürkert Type 2836 direct-acting electromagnetic proportional valve with a 5.0 mm seat orifice, ensuring dynamic response times under 500 ms.

Configured in an aluminium fluidic body with FKM seals, article 20092146 incorporates G 1/4" internal threaded process connections and a 9-pin D-Sub interface supporting 4–20 mA analogue setpoint and actual value signals, 1 digital input, and 1 relay output. Up to four calibration curves can be stored on the instrument, enabling flexibility across shifting process parameters.

Specific Device Configuration (Article 20092146)

Article 20092146 defines a specific build of the modular Type 8745 platform, equipped with the following technical parameters:

Parameter	Value
Article Number	20092146
Type Family	8745
Device Function	Controller (MFC)
Operating Medium 1	N2 nitrogen
Calibration Medium 1	Air
Nominal Operating Range	350 Nl/min
Turndown Ratio	1:50
Normal Operating Pressure	4 bar(ü)
Maximum Medium Pressure	6 bar
Outlet Pressure at Qnom	3 bar
Installation Position	Horizontal
Port Connection 1	Internal thread G 1/4" (Standard G)
Actuator Model	Type 2836 direct-acting electromagnetic proportional valve
Valve Seat Diameter	5 mm (3/16")
Fluidic Body Material	Aluminium
Valve Seat Seal	FKM (Fluor rubber)
External Seal Material	FKM (Fluor rubber)
Operating Voltage	24 V DC
Electrical Connection	D-Sub 9-pin male
Analogue Setpoint Signal	4–20 mA input
Analogue Feedback Signal	4–20 mA output
Digital Quantity Inputs / Outputs	1 digital input / 1 relay contact output
Protection Class	IP20 (with mating connector attached)

General Technical Data (Type 8745 Series Platform)

Type 8745 operates either as a mass flow controller (MFC) or mass flow meter (MFM) for gases across nominal flow ranges from 20 Nl/min up to 2500 Nl/min (referenced to nitrogen at 1.013 bar abs and 0 °C).

Technical Category	Specification Details
Housing Material	Polycarbonate (PC)
Base Block Materials	Aluminium or stainless steel 1.4404 / 316L
Sensor Wetted Materials	Stainless steel 1.4404 / 316L, Al2O3, PPS GF40, epoxy resin, silicon, silicon nitride
Supply Voltage	24 V DC (±10% tolerance, residual ripple ±2%)
Operating Medium	Neutral, pure gases (others on request)
Calibration Media	Operating medium or air
Medium Temperature	-10 °C to +70 °C (-10 °C to +60 °C with oxygen; 0 °C min. for electromotive valve)
Ambient Temperature	-10 °C to +50 °C (higher temperatures on request)
Storage Temperature	-10 °C to +70 °C
Relative Humidity	Max. 95% at +55 °C, non-condensing
Degree of Protection	IP20
Analogue Interfaces	4–20 mA, 0–20 mA, 0–10 V, or 0–5 V (input impedance > 20 kΩ voltage, < 300 Ω current)
Digital Communications	Modbus RS-485 / RTU, Industrial Ethernet: EtherCAT®, EtherNet/IP, Modbus TCP, PROFINET
Process Port Connections	G or NPT 1/4", 3/8", 1/2", 3/4", 1", sub-base, clamp connection (DN 20 to DN 40)

Actuator Variants: Electromagnetic vs Electromotive

The Type 8745 series supports two distinct valve actuation technologies:

Functional Characteristic	Electromagnetic Proportional Valve (Type 287x / 2836)	Electromotive Proportional Valve (Type 3280 / 3285)
Valve Position (De-energised)	Normally closed	Remains in current position (holds position)
Nominal Orifice Diameter	0.8 mm to 12 mm	2 mm to 20 mm
Flow Coefficient (Kvs)	0.02 to 2.5 m³/h	0.5 to 7.8 m³/h
Nominal Flow Range (QN, N2)	MFC: 20 to 1500 Nl/min; MFM: ≤ 2500 Nl/min	MFC: 20 to 2500 Nl/min
Max. Operating Pressure	Up to 25 bar (dependent on medium and orifice)	Up to 22 bar (MFM up to 25 bar)
Measuring Accuracy	±1.5% of measured value ±0.3% of full scale	±2% of measured value ±0.5% of full scale
Repeatability	±0.1% of full scale	±0.5% of full scale
Settling Time (t95)	< 500 ms	< 5 s
Power Consumption	Max. 12.5 W to 31.5 W (MFC); max. 4 W (MFM)	Max. 12 W moving; < 1 W holding; max. 4 W (MFM)
Total Weight (Aluminium Body)	Approx. 1800 g (with 16 W coil)	Approx. 1670 g (with Type 3280)
Total Weight (Stainless Steel)	Approx. 3100 g (with 16 W coil)	Approx. 2940 g (with Type 3280)

CTA Thermal Measurement Principle

Type 8745 utilizes a hot-film anemometer operating in Constant Temperature Anemometer (CTA) mode. The sensing element is placed directly within the main gas flow path, eliminating bypass flow tubing and preventing clogging.

Two resistors with precisely defined temperature coefficients are positioned inside the fluid stream, joined by three external precision resistors to create a Wheatstone bridge circuit:

• Resistor $R_T$ measures the real-time fluid temperature.
• Resistor $R_H$ is electrically heated and constantly maintained at a fixed, predefined excess temperature relative to the medium temperature measured by $R_T$.

Flowing gas extracts thermal energy from the heated resistor $R_H$. The heating current required by the control circuit to sustain the specified temperature differential represents the primary measured variable. Combined with aerodynamic flow profiling within the fluidic channel and calibration standards, the mass flow per unit time is calculated with high repeatability.

Mechanical Dimensions and Thread Depths

Article 20092146 is built on the compact base block (00 or A1) with G 1/4" internal thread tapping and an integrated Type 2836 proportional control valve.

Thread depth specifications for standard body connection ports:

Thread Designation (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
G 1	18
NPT 1	16.8

Body Length for Flow Rates Above 1500 Nl/min

For versions utilizing base block A3 engineered for flow rates $Q_N > 1500\text{ Nl/min}$, the overall unit length increases by 30 mm.

Electrical Interfaces and Pin Configuration

Article 20092146 utilizes a 9-pin D-Sub subminiature plug for 24 V DC power distribution, analogue process signaling (4–20 mA setpoint and actual feedback), and binary input/output lines.

Pin	D-Sub 9-Pin Assignment	Terminal Strip (6-Pin Variant Assignment)
1	Digital input	24 V DC supply
2	GND (supply voltage and digital input)	GND supply
3	24 V DC supply	Setpoint value input (+)
4	Relay contact, normally closed	Setpoint value input GND
5	Relay contact, common reference	Actual value output (+)
6	Setpoint value input (+)	Actual value output GND
7	Setpoint value input GND	—
8	Actual value output (+)	—
9	Actual value output GND	—
Housing	Cable shielding connection	—

Pressure Drop Characteristics and Nominal Gas Flow Rates

Pressure drop curves through the Type 8745 sensor body depend on gas density and base block design. The diagram below illustrates differential pressure curves with air.

Differential pressure for alternative media is calculated using the following conversion formula: $$ \Delta P_{\mathrm{Gas}} = \Delta P_{\mathrm{Air}} \cdot \sqrt{\frac{\rho_{\mathrm{NGas}}}{\rho_{\mathrm{NAir}}}} $$

Nominal flow capabilities for common industrial gases across the Type 8745 platform (referenced to 1013.25 mbar abs and 0 °C):

Gas Type	Min. $Q_N$ [Nl/min]	Max. $Q_N$ [Nl/min]
Acetylene	20	320 (air calibrated from 65 Nl/min)
Ammonia	8	1000
Argon	20	1600
Carbon Dioxide (CO2)	20	800 (1000 in MFM)
Air	20	2500
Methane	20	1200
Propane	20	200
Oxygen	20	2500
Nitrogen (N2)	20	2500

Software Integration and Accessories

Type 8745 belongs to the Bürkert EDIP (Efficient Device Integration Platform). Digital communication and parameter adjustment can be conducted using the Bürkert Communicator PC software via a CANopen-based service port.

Key functions supported in Bürkert Communicator:

• Configuration, parameter assignment, and real-time diagnostics of EDIP devices.
• Gas curve selection and live media switching.
• Signal mapping, zero-point recalibration, and guided calibration routines.
• Device configuration backup and firmware updating.

Micro-USB Connection Power Restriction

No external electrical power supply must be connected to the micro-USB service port. Power must be delivered strictly through the primary 24 V DC supply lines.

Configuration Memory Exchange

An optional memory card allows instant parameter transfer during hardware replacement. Swapping the memory card from a defective controller into a replacement device automatically restores operating configurations, provided both instruments share an identical article number.

Accessory Ordering Information

Description	Article Number
USB-büS interface set 2 (Type 8923) with büS stick, M12 cables, micro-USB adapter, and Y-splitter (0.7 m)	772551
Phoenix Class 2 power supply (Type 1573), 85–240 V AC / 24 V DC, 1.25 A, NEC Class 2	772438
DIN rail power supply (Type 1573), 100–240 V AC / 24 V DC, 1 A, NEC Class 2	772361
DIN rail power supply (Type 1573), 100–240 V AC / 24 V DC, 2 A, NEC Class 2	772362
DIN rail power supply (Type 1573), 100–240 V AC / 24 V DC, 4 A	772363
D-Sub analogue adapter cable, open strand end, 5 m	580882
D-Sub analogue adapter cable, open strand end, 10 m	580883
6-pin terminal strip (for standard analogue Type 8745)	On request
Configuration memory card	On request