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GE Oil & Gas
VariPak valves are factory-calibrated according to
the components specified in the customer order. If for
any reason this calibration has been disturbed (e.g.
after changing from direct to reverse valve action, or
replacing the plug and seat ring), all or some of the
adjustments below must be carried out in the following
order:
- Piston rod clevis (104b) adjustment.
- Plug stem adjustment.
- Limit stop adjustment.
- Cv adjustment.
- Positioner start-up pressure adjustment.
4.1 PISTON ROD CLEVIS ADJUSTMENT
4.1.1 Adjusting the piston rod clevis on the VariPak
28001 single-lever valve (Figures 14 and 26)
This adjustment is only required if the piston
(131) has been removed. In this case, it
should be carried out during reassembly,
before coupling the lever (113) to the clevises
(chap. MAINTENANCE - Reassembly. step H.,
page 17).
With the piston resting against diaphragm cover (137),
turn clevis (104b) so that the top of actuator bracket
(108) is 0.5 mm to 1 mm from the bottom of indicator
(126). A shim will simplify this operation. Admit enough
air pressure to disengage locknut (125) and tighten it
against indicator. Check that indicator (126) is correctly
positioned. Release air pressure.
4.1.2 Adjusting the piston rod clevis on the
Figure 14 - Piston rod clevis (104b) adjustment
VariPak 28002 adjustable-Cv valve (Figures 14 and 27)
This adjustment is only required if the piston
(131) has been removed.
In this case, it should be carried out during
reassembly, before coupling the levers (21)
and (22) to the clevises (chap. MAINTENANCE
- Reassembly. step K., page 17).
With the piston resting against diaphragm cover (137),
turn clevis (104b) so that the top of the actuator bracket
(108) is 0.5 mm to 1 mm from the bottom of indicator
(126). A shim will simplify this operation.
Couple lever No. 2 (22) in this clevis position. Admit
enough air pressure to disengage locknut (125) and
tighten it against the indicator. Check that indicator
(126) is correctly positioned. Release air pressure.
4.2 PLUG STEM ADJUSTMENT
4.2.1 Adjusting the plug stem on the VariPak 28001
single-lever valve (Figures 15, 16 and 26)
This adjustment should be carried out during
reassembly, before coupling the lever (113) to
the clevises.
A. Loosen nut (103) and turn the plug stem using a
screwdriver while blocking clevis (104a) until the clevis is
in the position shown in figure 15. Lock nut (103).
Figure 15 - Presetting the plug stem position
4. Calibration
