Page 225 - Bürkert

Control head for hygienic process valves

8681 • Universal attachment for hygienic
Control head • Contactless position measurement
process valves

system with 3 switching points
(Teach-In function)
• Coloured status display
• Magnetic manual override without
opening the device
• Communication interface
AS-Interface (option)

Type 8681 control head is optimised for decentralised automation of hy- Envelope Dimensions [mm] (see datasheet for details)
gienic process valves. Thanks to its universal adapter it can be combined
with all normal commercial butterfly valves, ball valves, single and double
seated valves. With a decentralised automation concept, the control head
takes over all pneumatic actuation, feedback and diagnostic functions up
to and including field bus communication. The housing is easy to clean
and features proven electrical IP protection and chemically resistant
materials for use in hygienic processing in food, beverage and pharma-
ceutical industries.

Technical Data C
A
Material B
Body PA, PPO, VA
Cover PC
Seal CR, EPDM
Control medium neutral gases, air DIN ISO 8573-1
(filter 5 µm recommended) A B C
Dust concentration class 5 (<40 µm particle size) 106.7 79 195.5
3
Particle density class 5 (<10 mg/m )
Pressure condensation point class 3 (<-20 °C)
3
Oil concentration class 5 (<25 mg/m )
Supply pressure 2.5 to 8 bar
Air capacity solenoid valve 1) 110 l /min - for pressurization and exhaust, Technical Data (continued)
N
(supply and exhaust air per lifting device
solenoid valve adjustable) 110 l /min - delivery condition Type of protection IP 65/67 acc. to EN 60529
N
200 l /min - max. typical flow rate (throttle) Protection class 3 (AS-Interface, 24 VDC, DeviceNet); 1 (120 VAC)
N acc. to DIN EN 61140
Pilot air ports
Air inlet and outlet G 1/4” Fieldbus communication AS-Interface, DeviceNet
Service ports G 1/8” EG-Conformity EMV2004/108/EG; ATEX 94/9/EG
Position sensor Non-contact Position Sensor, 3 self-regulated Ignition protection ATEX II 3G Ex nA IIC T4
switching points PNP (Teach-In-function) closer ATEX II 3G Ex tD A22 T135°C
(normally open), PNP-output short-circuit proof,
with clocking short-circuit protection
Outlet current Max. 100 mA per feedback signal
Stroke range 0 to 80 mm
Resolution ≤ 0.1 mm
Total error ± 0.5 mm - when using a target for the dimen-
sional drawing, material 1.4021 and a piston
rod (Ø 22 mm, material 1.4301) (error refers to
the reproducibility of a teach-position)
Ambient temperature -10 °C to +55 °C
+5 °C to +55 °C (ATEX II 3G Ex nA IIC T4;
ATEX II 3G Ex tD A22 T135°C)
Installation As required, preferably with actuator in upright
position
1) QNn-value acc. to the definition with decrease in pressure from 7 to 6 bar absolute
with 20°C.

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