BURKERT Type 8694 (Article 389238) is a compact digital electropneumatic positioner designed for integrated mounting on pneumatically controlled process control valves. The set-point value setting default occurs via standard signal 4-20 mA or via fieldbus/digital communication (AS-Interface, IO-Link, or Bürkert system bus büS). A contactless sensor element records the valve spindle position, ensuring wear-free operation. Simple start-up is facilitated by the automatic X.TUNE function and DIP switch settings.

The positioner forms a complete functional unit when combined with pneumatic actuators, such as the ELEMENT Type 23xx or 2103 series. It features an integrated pilot air duct in the actuator, eliminating the need for external tubing and enhancing the robustness of the assembly.

Key Features

• Compact and Robust: Stainless steel and PPS body design suitable for harsh industrial environments.
• Contact-free Position Sensor: Inductive (linear) or magnetic (rotary) measurement principle for wear-free position detection.
• Automatic Start-up: X.TUNE function for automatic adjustment of the positioner to the specific valve operating conditions.
• Integrated Control Air Routing: Pilot air duct is integrated directly into the actuator.
• Digital Communication: Available with AS-Interface, IO-Link, or Bürkert system bus (büS) based on CANopen.

Start-up Recommendation

Run the X.TUNE automatic adjustment function whenever the pilot pressure is available during subsequent operation. It is recommended to run X.TUNE without operating medium pressure to exclude interference caused by flow forces.

Material Specifications

No.	Element	Material
1	Cover	PC
2	Seal	EPDM
3	Body casing	Stainless steel
4	Seal	EPDM
5	Screws	Stainless steel
6	Push-in connector / Threaded port G 1/8	POM / Stainless steel
7	Basic housing	PPS
8	M12 plug connector	Stainless steel
9	Screws	Stainless steel

Dimensions

Dimensions in mm, unless otherwise stated. Applicable for mounting on ELEMENT control valve Type 23xx / 2103.

Electrical Connections

The positioner supports various communication protocols. The specific pin assignment depends on the ordered variant.

Bürkert System Bus (büS) Connection

Pin	Description	Cable colour
1	CAN shielding	CAN shielding
2	+ 24 V DC ± 25%, max. residual ripple 10%	Red
3	GND/CAN_GND	Black
4	CAN_H	White
5	CAN_L	Blue

IO-Link Connection (Port Class B)

Pin	Description	Pin assignment
1	L +	24 V DC (System supply)
2	P24	24 V DC (Actuator supply)
3	L -	0 V / GND (System supply)
4	C/Q	IO-Link (Communication)
5	N24	0 V / GND (Actuator supply)

Performance Specifications

Signal Flow Diagram

The position measuring system records the current position (POS) of the pneumatic actuator. The position controller compares this actual position value with the set-point value (CMD). In case of a control deviation, a pulse-width modulated voltage signal is sent to the control system as a manipulated variable to aerate or deaerate the pneumatic actuator.

Approvals and Conformities

Explosion Protection

For variants with ATEX/IECEx approval (e.g., II 3D Ex tc IIIC T135 °C Dc / II 3G Ex ec IIC T4 Gc), the device may only be used according to the specifications on the separate approval sticker. Ensure that the system cannot be activated unintentionally during installation or maintenance in potentially explosive atmospheres.

• ATEX: BVS 14 ATEX E 008 X (II 3D Ex tc IIIC T135 °C Dc / II 3G Ex ec IIC T4 Gc)
• IECEx: IECEx BVS 14.0009 X
• North America: cULus certificate E238179; FM Explosion Protection (Class I, Zone 2, AEx ec IIC T4 Gc)
• CCC: China Compulsory Certification for hazardous applications.