Instruction Manual

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Supplement to Fisherr FIELDVUEt DVC6000 or

DVC6200 Digital Valve Controller Instruction

Manuals

Implementation of Lock‐in‐Last Strategy

Many applications require a valve assembly to remain in the position it was prior to a specific control system failure

(lock‐in‐last position). Functionality and safety can be designed into valve assemblies with FIELDVUE digital valve

controllers by utilizing an array of accessories. The following paragraphs describe standard solutions for a number of

generic lock‐in‐last applications with DVC6000 or DVC6200 digital valve controllers.

Note

This instruction manual supplement is for use with HARTr communicating FIELDVUE DVC6000 or DVC6200 digital valve

controllers only.

Lock‐in‐Last on Loss of Supply Pressure

Once the supply pressure falls below a minimum value, the digital valve controller can no longer position a valve

assembly; the valve will start to go to the actuator “at rest” position. The locking device senses this change and

activates, preventing the remaining air from venting. The valve is “locked‐in” this new position.

Note

The locked‐in valve position depends on the exhausting speed of the actuator.

Assemblies with Single‐Acting Actuators

A Fisher 164A three‐way switching valve should be used for locking a single‐acting actuator in place on loss of supply

pressure. Figure 1 is a schematic representing proper assembly layout. In normal operation, the digital valve controller

output passes through the switching valve from port A to port B and on to the actuator.

Instruction Manual Supplement

D103261X012

DVC6000/DVC6200 Digital Valve Controllers

February 2011

Summary of content (8 pages)

PAGE 1
Instruction Manual Supplement DVC6000/DVC6200 Digital Valve Controllers D103261X012 February 2011 Supplement to Fisherr FIELDVUEt DVC6000 or DVC6200 Digital Valve Controller Instruction Manuals Implementation of Lock‐in‐Last Strategy Many applications require a valve assembly to remain in the position it was prior to a specific control system failure (lock‐in‐last position).
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Instruction Manual Supplement DVC6000/DVC6200 Digital Valve Controllers February 2011 D103261X012 Figure 1. Lock‐in‐Last on Loss of Supply Pressure for an Assembly with a Single‐Acting Actuator (Fisher DVC6000 Depicted) FISHER 164A THREE‐WAY SWITCHING VALVE D A B C DIGITAL VALVE AIR SUPPLY OUTPUT SUPPLY CONTROLLER FISHER 67CFR FILTER/REGULATOR In a fail condition, the pressure at port D is below the switching valve's set point, causing the switching valve to trip.
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Instruction Manual Supplement D103261X012 DVC6000/DVC6200 Digital Valve Controllers February 2011 Connection of the digital valve controller output to a double‐acting actuator determines the action of the actuator. Figure 2 shows the digital valve controller providing lower cylinder pressure through ports D and E, and upper cylinder pressure through ports A and B.
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Instruction Manual Supplement DVC6000/DVC6200 Digital Valve Controllers February 2011 D103261X012 Figure 3. Lock‐in‐Last Strategy for an Assembly with a Single‐Acting Actuator Using a Solenoid Valve (Fisher DVC6000 Depicted) SOLENOID VALVE (ENERGIZED) 2 1 24 VDC POWER SUPPLY 3 1 FISHER 67CFR FILTER/REGULATOR DIGITAL VALVE OUTPUT SUPPLY AIR SUPPLY CONTROLLER NOTE: 1 A SOLENOID VALVE WITH A MINIMUM CV OF 0.
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Instruction Manual Supplement DVC6000/DVC6200 Digital Valve Controllers D103261X012 February 2011 The solenoid valve in this solution does not require a Cv greater than 0.49. Flow capacity of this valve can be much smaller. An example of a proper solenoid valve for this assembly is the 8320 Series three‐way solenoid valve. As with all solenoid valves, ensure that the solenoid valve operating pressure differential rating is adequate for the supply pressure.
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Instruction Manual Supplement DVC6000/DVC6200 Digital Valve Controllers February 2011 D103261X012 Figure 5.
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Instruction Manual Supplement DVC6000/DVC6200 Digital Valve Controllers D103261X012 February 2011 Figure 6.
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Instruction Manual Supplement DVC6000/DVC6200 Digital Valve Controllers February 2011 D103261X012 Phoenix Threshold Switch Specifications(1) Switch Model Number MCR‐2SP/UI-DC Size 44.5 X 76.