PWM Control
The Burkert Type 8691 control head is designed for decentralised automation of ELEMENT Type 21xx pneumatic process valves. The valve position is registered via a contact-free, analogue sensor element which automatically detects and saves the valve end position using the Teach function during start-up. The integrated pilot valve controls single or double-acting actuators. An optional communication interface, AS-Interface, IO-Link or büS (based on CANopen) can be selected.
The design of the control head and the actuator permits an integrated pilot air duct without external piping. Besides the electrical position feedback, the device status is shown directly on the control head itself through coloured powerful LEDs, even in difficult ambient conditions. The housing is easy to clean and features proven IP protection and chemically resistant materials for use in hygienic processing in the food, beverage and pharmaceutical industries. Focused on plant wash-down applications, the IP protection of the housing is supported by positive pressure inside the control head.
Key Features:
- Contact-free inductive valve position registration (Teach function)
- Colour illuminated status display
- Integrated pilot air duct in the actuator
- Fieldbus interface AS-Interface, IO-Link or Bürkert system bus (büS)
- With ATEX II cat. 3G/D / IECEx approval
General Technical Data
| Product properties | Description |
|---|---|
| Material | Body: PPS, stainless steel Seal: EPDM Cover: PC |
| Operation | Operating keys: 2 Service interface: Connection to PC via USB büS interface set Configuration tool: Bürkert Communicator |
| Commissioning | Setting of valve end position: Through automatic or manual teach function Manual operation of pilot valve: Yes |
| Status display | Display of the device and valve status: High performance LEDs (colours individually adjustable) |
| Communication | Fieldbus: AS-Interface, IO-Link Digital: Bürkert system bus (büS) (based on CANopen) |
| Position sensor | Analogue position sensor: Inductive (contactless) with self-adjusting switching points (PNP) (NPN on request) |
| Stroke range | Valve spindle: 2.5...45 mm |
Supply Pressure Requirement
The supply pressure applied must be 0.5 to 1 bar above the minimum required pilot pressure of the valve actuator.
Pneumatic and Electrical Data
| Parameter | Value |
|---|---|
| Control medium | Neutral gases, air, quality class according to ISO 8573 - 1 |
| Supply pressure | 3...7 bar |
| Pilot air port | Threaded connection G 1/8, stainless steel |
| Circuit function | Single-acting (3/2-way) and double-acting (5/2-way) |
| Air flow rate | 250 lN/min (for aeration and ventilation) |
| Actuator series/size | Type 21xx, actuator ∅ 70/90/130/225 mm |
| Operating voltage (24V) | 24 V DC ± 25% (UL: NEC Class 2) |
| Operating voltage (IO-Link) | 24 V DC ± 25% (according to specification) |
| Operating voltage (büS) | 18...30 V DC (according to specification) |
Approvals and Conformities
- Explosion protection (ATEX/IECEx): II 3D Ex tc IIIC T135 °C Dc / II 3G Ex ec IIC T4 Gc
- North America (USA/Canada): cULus certificate: E238179. FM Explosion Protection: Increased Safety for Class I, Zone 2, AEx ec IIC T4 Gc hazardous locations.
- China Compulsory Certification (CCC): The products with Ex approval are suitable for import and use for hazardous applications in China.
Explosion Protection Safety
When used in explosion-risk areas, observe the information provided on the separate Ex type label and the additional explosion-related operating instructions. Do not use the device in environments with gases or dusts that have an ignition temperature lower than specified on the approval label.
Materials
| No. | Element | Material |
|---|---|---|
| 1 | Cover | PC |
| 2 | Seal | EPDM |
| 3 | Body casing | Stainless steel |
| 4 | Seal | EPDM |
| 5 | Push-in connector | POM/stainless steel |
| 6 | Basic housing | PPS |
| 7 | Screws | Stainless steel |
| 8 | M12 plug connector | Stainless steel |
Dimensions
Dimensions in mm, unless otherwise stated.
Product Connections
Without fieldbus communication 24 V DC
M12 circular plug, 8-pin
| Pin | Description |
|---|---|
| 1 | Digital output (DO2+), end position with actuator activated |
| 2 | Digital output (DO1+), end position with actuator deactivated |
| 3 | Operating voltage GND |
| 4 | Operating voltage + 24 V DC |
| 5 | Digital input valve control + |
| 6 | Digital input valve control – |
| 7 | Not assigned |
| 8 | Not assigned |
IO-Link Connection
M12 circular plug, 5-pin, port class A
| Pin | Description | Pin assignment |
|---|---|---|
| 1 | L + | 24 V DC (System supply) |
| 2 | I/Q | NC (Not connected) |
| 3 | L - | 0 V (GND) (System supply) |
| 4 | C/Q | IO-Link (Communication) |
| 5 | NC | NC (Not connected) |
Bürkert system bus (büS) Connection
M12 circular plug, 5-pin
| Pin | Description | Cable colour |
|---|---|---|
| 2 | V + | Red |
| 3 | V - | Black |
| 1 | Drain/shielding | - |
| 4 | CAN_H | White |
| 5 | CAN_L | Blue |
Combination Options with Pneumatic Process Valves
A complete TopControl control valve system consists of a positioner Type 8691 and an ELEMENT process valve Type 21xx.
- Type 8801-YE-H: Valve system ELEMENT Type 2100 + Type 8691
- Type 8801-GC-H: Valve system ELEMENT Type 2101 + Type 8691
- Type 8801-DF-H: Valve system ELEMENT Type 2103 + Type 8691
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