Limit Stop Adjustment - GE Masoneilan VariPak 28001 Instruction Manual

B. Fit lever (113) with spring clamp (115) positioning hole
facing upwards, fit pin (105) into hole A, then fit pin
(18) into clevis (104a). Note: All pins should be greased
slightly before fitting.
C. Press the lever on the actuator side to check for plug/
seat ring leaks at ΔP 3.5 barg (50 psig). If the valve is
equipped with a handwheel, lever (113) should not
touch lever arm stop (122). If the valve leaks, release
the pressure at the inlet and remove pin (18) of clevis
(104a), then loosen nut (103). Loosen the plug stem in
order to move the clevis up (104a). A complete turn
moves the position up by 1 mm. Then tighten the
locknut (103) again.
D. Check that the distance between clevis (104b) pin
and the hole in lever (113) is approximately 2 mm.
If necessary, adjust the position of clevis (104a) to
obtain this distance, see figure 16. This value provides
the initial compression of actuator spring (134).
Figure 16 - Adjusting the lever (113)
E. Admit enough air pressure to the actuator to drive
piston clevis (104b) upwards. Couple the clevis to
lever (113) using pin (124).
F. Release the actuator pressure and repeat the plug/
seat ring leak test at ΔP 3.5 barg (50 psig). Dimension
A should be the same as in figure 16 . Release the
valve pressure once this step is completed.
4.2.2 Adjusting the plug stem on the VariPak 28002
adjustable-C v valve (Figures 27, 28 and 29)
Once all the coupling operations are completed,
proceed as follows:
A. Admit enough pressure to the actuator to drive out
the piston rod far enough to place a shim under
the indicator (126). Use a 1.5 mm shim for an Air-to-
Open actuator, and a 25 mm shim for an Air-to-Close
actuator. Release the air pressure after inserting the
shim.
At this closing point where the plug is not
tightened onto the seating, the slides of
levers No. 1 and 2 should be perfectly
parallel. This characteristic makes it possible
to change the adjustment knob (24) position
later to obtain the required real C v value.
B. Loosen adjustment knob (24) and slide it along lever
No. 1 to the maximum C v position on adjustment
plate (25). Fully tighten adjustment knob (24).
C. Loosen locknut (103) and, using a screwdriver, turn
the plug stem until the plug is just touching the seat
ring. If the valve has been removed from the pipe,
a bubble test can be performed on the calibration
bench to obtain a very accurate adjustment. Using
the screwdriver to hold the plug stem in position,
tighten locknut (103) against clevis (104a).
D. Admit air pressure again to remove the shim, then
release the pressure.
Note: On an Air-to-Open actuator, shim thickness may
be increased or decreased by one or two-tenths of a
millimeter to ensure that levers No. 1 and 2 are perfectly
parallel and to obtain the required tightness on closing,
especially for very low C v values (C v < 0.10).
4.3 LIMIT STOP ADJUSTMENT (Figure 5)
VariPak valves include a limit stop to prevent damage to
the plug and seat ring and/or plug stem in the event of
actuator or handwheel overstroke. This device consists
of a nut (180) acting as a stop, screwed onto the piston
rod inside the spring chamber, and a locknut (181).
If necessary, this device should be adjusted
immediately after plug stem adustment (see section
4.2).
A. Remove the shim (for VariPak 28002 adjustable- C v
valve only) and admit sufficient supply pressure to
close the valve. Turn locknut (181) on the piston rod
until it touches locknut (125). Turn limit stop (180) until
it just touches the inside of actuator bracket (108).
B. Hold the limit stop with a 12 mm wrench and tighten
locknut (181). Release the air pressure.
Masoneilan VariPak Adjustable Cv Control Valves Instruction Manual | 13