SVI-II Instruc Man.book - Fagerberg

Masoneilan Dresser
SVI II AP Instruction Manual
Note:
Maximum allowable air supply pressure to the SVI II AP varies
according to actuator and valve size and type. See pressure drop
tables in valve specification sheets to determine correct positioner
supply pressure. Minimum supply pressure should be 5 to 10 psi
(.345 bar - .69 bar) (34.485 - 68.97 kPa) above maximum spring
pressure.
Mounting the
SVI II AP on
Rotary Valves
This procedure is used to mount the SVI II AP on rotary control valves that
have less than 60 degrees rotation, such as a Camflex ® or a Varimax ® . For
valves that have rotation greater than 60 degrees refer to “Rotary - 90 Degree”
on page 13
Required Tools
The following tools are needed to complete the rotary valve installation:
To mount the SVI II AP:
3⁄16 inch Hex Key with tee handle
5⁄32 inch Hex Key
3 mm, 4mm, 5mm Hex Key
7⁄16 inch Wrench
1. Attach the SVI II AP rotary mounting bracket to the valve actuator
using two (2) 5⁄16 - 18 UNC flat-head cap screws. The
SVI II AP will be mounted as shown in Figure 5 on page 11, ATO or
in Figure 6 on page 12, ATC. In the preferred mounting position, the
long end of the mounting bracket is on your left when facing the
actuator, for any position of the valve and actuator.
2. Bolt the extension shaft to the valve position take-off shaft using a
1⁄4 - 28 UNF socket flathead screw. Secure the machine screw
holding the extension shaft with a torque of 144 in-lbs (16.269 N-m).
3. Upon internal valve pressure the thrust shaft is pushed out to the
mechanical stops, usually a thrust bearing. On valves where the
valve position take-off is mounted directly on the end of the plug
shaft, a Camflex for example, the shaft must be bearing on its stop to
properly set up the SVI II AP positioner. During hydrostatic testing
the shaft is thrust to its stop and a normally tightened packing will
retain it in that position.
4. On vacuum service, the valve shaft may be drawn into the body by
the vacuum acting on the shaft, but the magnetic coupling must be
assembled flush with the mounting bracket with the shaft pulled fully
out to its thrust bearing. Check that the endplay from the vacuum
position to the fully extended position is less than 0.06 in. (1.524
mm)
5. Slide the magnet holder into the extension shaft. The location of the
magnets is in the ring of the magnet holder. The magnetic axis is the
imaginary line through the center of both magnets.
6. Rotate the magnet holder so that the magnet axis is vertical when
the valve is in the closed position. See Figure 5 and Figure 6.
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