PWM Control
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 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
Compatible Process Valves
The Type 8691 control head can be combined with the following Bürkert process valves:
- Type 2100: Pneumatically operated 2/2-way angle seat valve ELEMENT
- Type 2101: Pneumatically operated 2/2-way globe valve ELEMENT
- Type 2103: 2/2-way diaphragm valve with pneumatic stainless steel actuator (Type ELEMENT)
- Type 2104: T-diaphragm valve with pneumatic actuator in stainless steel (Type ELEMENT)
- Type 2105: Tank bottom diaphragm valve with pneumatic actuator in stainless steel (Type ELEMENT)
- Type 2106: Pneumatically operated 3/2-way seat valve ELEMENT
General Technical Data
| Product properties | Description |
|---|---|
| Body material | PPS, stainless steel |
| Seal material | EPDM |
| Cover material | PC |
| Operating keys | 2 |
| Configuration tool | Bürkert Communicator |
| Setting of valve end position | Through automatic or manual teach function |
| Status display | High performance LEDs (colours individually adjustable) |
| Analogue position sensor | Inductive (contactless) with self-adjusting switching points (PNP) |
| Control medium | Neutral gases, air, quality class according to ISO 8573-1 |
| Supply pressure | 3 to 7 bar (must be 0.5 to 1 bar above the minimum required pilot pressure) |
| Pilot air port | Threaded connection G 1/8, stainless steel |
| Air flow rate | 250 l/min (for aeration and ventilation) |
| Actuator series/size | Type 21xx, actuator ∅ 70/90/130/225 mm |
| Ambient temperature | -10 to +55 °C (with pilot valve) |
| Degree of protection | IP65/IP67 according to EN 60529, 4X according to NEMA 250 Standard |
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): Products with Ex approval are suitable for import and use for hazardous applications in China.
Materials
| No. | Element | Material |
|---|---|---|
| 1 | Cover | PC |
| 2 | Seal | EPDM |
| 3 | Body casing | Stainless steel |
| 4 | Seal | EPDM |
| 5 | Push-in connector / Threaded connections G 1/8 | POM/stainless steel / Stainless steel |
| 6 | Basic housing | PPS |
| 7 | Screws | Stainless steel |
| 8 | M12 plug connector | Stainless steel |
Dimensions
Mounting on process valve ELEMENT Type 21xx (Dimensions in mm, unless otherwise stated):
Electrical 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 (Supply voltage: 18...30 V DC) |
| 3 | V - | Black (Supply voltage: 18...30 V DC) |
| 1 | Drain/shielding | - |
| 4 | CAN_H | White |
| 5 | CAN_L | Blue |
Ordering Information
Linear displacement sensor/integrated pilot air duct For ELEMENT Type 21xx actuator series. All standard variants are UL-approved.
| Communication | Electrical connection | Circuit function | Article no. (Standard / cULus) |
|---|---|---|---|
| IO-Link | M12 circular plug connector port class A | Single-acting | 20024938 |
| IO-Link | M12 circular plug connector port class A | Double-acting | 20024954 |
| IO-Link | M12 circular plug connector port class B | Single-acting | 20024946 |
| IO-Link | M12 circular plug connector port class B | Double-acting | 20024960 |
| Bürkert system bus (büS) | M12 circular plug connector | Single-acting | 20024974 |
| Bürkert system bus (büS) | M12 circular plug connector | Double-acting | 20024982 |
| Without fieldbus communication | M12 circular plug connector | Single-acting | 20024842 |
| Without fieldbus communication | M12 circular plug connector | Double-acting | 20024875 |
(Note: Additional variants for AS-Interface, ATEX/IECEx approvals, and rotary position sensors are available on request.)
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