BURKERT 20066262 (Type 8745) is a mass flow controller (MFC) configured for CO2 (carbon dioxide) with a nominal flow range of 250 SLPM. It features a G 1/2" internal thread connection, an aluminium body with FKM seals, and operates on a 24 V DC supply with a 4-20 mA analogue interface. The Type 8745 utilizes a thermal inline sensor located directly in the main gas stream, achieving a settling time of < 500 ms. As the actuator, a direct-acting electromagnetic proportional valve (Type 2875) guarantees high response sensitivity.

General Technical Data

Feature	Specification
Operating Medium	CO2 (carbon dioxide)
Operating Range	250 SLPM
Supply Voltage	24 V DC (±10% tolerance, ±2% residual ripple)
Port Connection	G 1/2" Internal thread
Input/Output Signal	4-20 mA
Body Material	Aluminium
Seal Material	FKM (Fluor rubber)
Max Operating Pressure	7 bar
Measuring Range	1:50
Protection Degree	IP20

Measurement Principle

This sensor works as a hot-film anemometer in the CTA (Constant Temperature Anemometer) operational mode. Two resistors with a precisely specified temperature coefficient are 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.

Variant with Electromagnetic Proportional Valve

The MFC variant uses direct-acting proportional valves (Type 2875 for this configuration). These electromagnetic proportional valves are normally closed and provide high measuring accuracy and repeatability.

• Valve Position: Normally closed
• Nominal Diameter: 4 mm (5/32")
• Settling Time (t95): < 500 ms
• Measuring Accuracy: ±1.5% MV, ±0.3% FS (under calibration conditions)
• Repeatability: ±0.1% FS

Approvals and Conformities

Conformity Options

Depending on the specific configuration, the Type 8745 family supports various approvals.

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

Product Connections (Analogue)

The 20066262 model utilizes a 4-20 mA analogue interface.

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