Flowserve Valtek VL-C Spring Cylinder Linear Actuators - Manual (Page 6)

54-6 Flowserve Corporation, Valtek Control Products, Tel. USA 801 489 8611
stem spacer on the actuator stem according to the
proper air-action (see either Figure 1 or 2). Replace
the piston quad-seal. Air-to-extend configurations
require the spring button to be stored under actua-
tor stem locknut. Tighten the locknut firmly by
holding the flats on the actuator stem.
NOTE: When reassembling dual or heavy-duty
spring actuators, the spring guide must be first
inserted under the actuator stem locknut (see Fig-
ures 3 and 4).
6. For air-to-extend configurations, place the spring
under the piston and insert the actuator stem
through the yoke, being careful not to pinch the
actuator stem O-ring or gall the stem and stem
bushing. For air-to-retract configurations, insert the
actuator stem through the yoke and place the
spring(s) and spring button above the piston.
7. Install the tie rods into the yoke using Loctite
No. 242 NSF61 or equivalent.
8. Install the cylinder, making sure the cylinder is
completely seated on the yoke. Care should be
taken not to scar or cut the piston and yoke O-rings.
9. Replace the cylinder end cap and secure to the tie
rods using new self-locking nuts. Refer to Table II
for the appropriate torque values.
WARNING: To avoid personal injury, the cylin-
der end cap must be solidly in place. The cylin-
der end cap may fly off when pressurized.
10. Reinstall the adjusting screw fitted with a new
adjusting screw gasket.
NOTE: Be certain the hole in the spring button is
directly centered under the adjusting screw hole in
the cylinder on air-to-retract configurations.
11. Tighten the adjusting screw enough to provide an
air seal with the gasket. Do not overtighten.
Table II: Tie Rod Nut Torque Values
Actuator Size Torque Value (ft.-lbs.)
100 207 – 229
150, 200 336 – 371
12. Reinstall the stem bellows and stem clamp.
NOTE: To ensure maximum clamping strength
when installing the stem clamp, make sure the stem
clamp bolting is perpendicular to one of the slots
machined into the actuator stem.
13. Apply air over the piston. Tighten the stem clamp
bolting with the stem clamp adjusted to point at the
closed position of the stroke indicator plate.
NOTE: If the actuator is installed on a Flowserve
valve, refer to the appropriate installation, opera-
tion, maintenance instructions for correct plug stem
thread engagement.
14. Reconnect tubing, supply and signal lines.
Reversing the Air-action
To change the air action from air-to-retract to air-to
extend, or vice versa, refer to Figures 1, 2 or 4:
NOTE: Dual spring actuators are not reversible.
1. Disassemble the actuator according to the Disas-
sembling the Actuator section.
2. For air-to-retract action, reassemble the actuator
with stem spacer and spring button over the piston.
3. For air-to-extend action, reassemble with spring
and stem spacer below the piston and with the
spring button stored above the piston.
4. Reassemble the actuator according to the Reas-
sembling the Actuator section.
5. The positioner must also be reversed. See the
appropriate positioner maintenance instructions.