6  REMOVE AND INSTALL ACTUATOR
  General Information
  We recommend separating the actuator from 
the valve during all repair work. However, many 
maintenance and adjusting operations can be carried 
out in an installed condition.
6.1  Remove series 4 actuator
  (see Fig 1 + 2) 
  For series 2 actuator see 6.3
  For actuators with spring-to-close, go to 6.1.1 
  For actuators with spring-to-open, go to 6.1.2
6.1.1 Shut off air supply. 
  WARNING: Depressurise the line to atmospheric 
pressure and drain all fluids from the valve before 
working on the actuator. Failure to do so can cause 
serious injury.
6.1.2  Remove cap and nameplate. Tighten zero adjusting 
nut until it just touches the surface of the spring 
housing. This relieves the plug from actuator spring 
pressure. If the actuator is fitted with a handwheel 
this can be used to relieve the plug from actuator 
spring pressure.
3.1.3  Using a wrench, secure the actuator stem against 
turning and using a second wrench loosen the stem 
locknuts. If the actuator is fitted with a coupling 
refer to the procedure described in the maintenance 
instructions for the I/P actuator.
  CAUTION: The actuator stem must not be rotated, 
as this will cause damage to the diaphragm.
6.1.4  Loosen gland and clamp nuts.
6.1.5  Secure plug stem against turning and unscrew actuator from plug stem by rotating counter-clockwise.
  CAUTION: Ensure that the plug assembly is not 
rotated with the plug seated. This may cause irreparable damage to the seating faces.
6.1.5  Remove actuator and remove at the same time 
locknut, travel indicator disc, gland nut and clamp 
nut.
3.2  Install series 3 actuator
  Information:
  •  Before the actuator is installed, it must be 
calibrated according to section 3 of the instructions 
„Pneumatic and Electro-pneumatic Actuators“.
  •  All worn or damaged parts must be replaced. Reusable parts must be clean.
6.2.1  Position actuator with clamp nut, gland nut, locknuts 
and travel indicator disc on the valve.
6.2.2  Only for „spring-to-close“ actuators:
  Screw actuator onto plug stem by rotating clockwise, 
until the yoke plate just touches the valve housing 
and the actuator is aligned forward. If the actuator 
is fitted with a coupling refer to the procedure described in the maintenance instructions for the I/P 
actuator.
  CAUTION: Ensure that the plug assembly is not rotated 
with the plug seated. This may cause irreparable damage to the seating faces.
  Only for „spring-to-open“ actuators: 
  Lift plug stem and screw it into the lower coupling half 
until the distance between „plug in seat“ and „plug 
raised“ approximately corresponds to the specified 
stroke.
6.2.3  Tighten clamp nut and gland nut.
6.2.4  Adjust seat tightness by screwing/unscrewing the plug 
stem in/out of the actuator stem.
  CAUTION: Ensure that the plug assembly is not rotated 
with the plug seated. This may cause irreparable damage to the seating faces. Open valve, make adjustment, 
close valve and check for leaks. If the valve is fitted 
with a bellows seal the plug stem may NOT be rotated 
at all. In the case of a bellows seal adjustments are 
made with the coupling. 
6.2.5  After adjusting, secure the locknuts and the travel 
indicator disc lying between them against actuator 
stem and align the travel indicator on the yoke rod.
6.3  Remove series 2 actuator
  (see Fig. 1a) 
  For series 4 actuator see 6.1
6.3.1 Shut off air supply.
  WARNING: Depressurise the line to atmospheric 
pressure and drain all fluids from the valve before 
working on the actuator. Failure to do so can cause 
serious injury.
6.3.2 Disconnect all tubing.
6.3.3 Remove 2 screws and remove coupling.
6.3.4 Remove yoke rod retaining nuts and lift actuator 
assembly from the valve.
6.3.5 Remove coupling insert and it’s locknut from plug 
stem.
  CAUTION: Ensure that the plug assembly is not 
rotated with the plug seated. This may cause 
irreparable damage to the seating faces.
6.4  Install series 2 actuator
  (see Fig. 1a)
  The actuator stem must be fully extended: 
  Actuators with air-to-open action must be fully 
vented. Actuators with air-to-close action apply 
supply pressure.
  Manually depress the plug stem to ensure the plug is 
fully seated.
6.4.1 Screw coupling insert locknut and coupling insert as 
far as possible onto plug stem.
6.4.2 Place the actuator assembly on the valve engaging the 
yoke rod threads in the lower yoke plate and ensuring 
the actuator faces in the correct direction.