THD SERIES S11-S27 HEAVY DUTY ACTUATORS
Installation & Maintenance Manual
1
September 25, 2015
www.atcontrols.com
documents\products\IOM\IOM8036
THD-SERIES S11DA280 THRU S27DA1020 & S11SR280 THRU S27SR1020 DOUBLE ACTING &
SPRING RETURN SCOTCH YOKE ACTUATORS
INTRODUCTION
A-T Controls THD scotch yoke actuators have been
designed and engineered to provide high cycle-life to meet the
demands of our customers. The actuators are equipped with
dual travel stops and accessory mounting.
!!!WARNING!!!
FOR YOUR SAFETY,
IT IS IMPORTANT THAT BEFORE
REMOVING ANY COMPONENTS OF THE ACTUATOR,
ENSURE THAT ALL PNEUMATIC AND ELECTRICAL
SUPPLIES ARE DISCONNECTED AND LOCKOUT AND
TAGOUT PROCEDURES ARE IMPLEMENTED. PLEASE
CONSULT FACTORY IF YOU HAVE ANY QUESTIONS
ON ANY OF THE PROCEDURES LISTED BELOW.
1. Installation of Actuator
Triac actuators are adapted to the valve by means of an
intermediate bracket and coupler. The coupler adapts the
output of the actuator to the valve shaft. Standard mounting
kits provide for mounting the actuator in the direction of the
pipe. If different orientations are required please consult the
factory when the order is placed.
Before mounting the actuator on the valve insure that both
units are in the proper orientation, i.e. both units open or
closed. Make sure the coupler fits into the actuator and onto
the valve before assembly. Also check the bracket for proper
fit. After mounting the actuator, it may be necessary to adjust
the travel stops for proper open and closed valve position.
Always consult the manufactures installation manual for
specific details before proceeding. Pneumatically stroke the
actuator several times to assure smooth proper operation...
2. Air Supply
Pneumatic piping to the actuator and associated accessories
should follow the best practices for instrument pneumatic
piping systems, I.E. lines free of water, oil, pipe sealant or
other contaminants. The operating medium is to be filtered
dry air or inert gas which is filtered to 50 micron particles size
or less. It is extremely important that the actuator be powered
with the proper air pressure and air volume. Maximum
working pressure is 100 PSI. Consult the THD series catalog
for a complete listing of MOP (maximum operating pressure)
and MAWP (Maximum Allowable Working Pressure)
Spring return actuators are vented to the atmosphere through
the front flange. The Pressure Cylinder must be purged if a
corrosive atmosphere exists. Please contact Triac Controls for
possible solutions if this condition exists.
3. Lubrication
Triac actuators are factory lubricated for life and additional
lubrication is not normally required. However, for actuators
performing 100,000 cycles or more, an oil mist lubricator is
recommended. Oil mist lubrication requires a mineral oil type
ISO VG32 Class 1 for usage in temperature range 15 to 158
Deg. F. Oil mist lubricator must be set to the lowest setting.
Once begun, the oil mist lubrication cannot be discontinued.
CAUTION
If the actuator is equipped with a pneumatic positioner or
pneumatic controller, oil mist lubricated air cannot be used
unless the instrument manufacturer indicates that the
instrument is compatible with lubricated air.
4. Actuators in Storage or infrequently cycled.
Actuators in storage should be kept dry and protected from
adverse conditions until installed. Original port protectors must
be kept in the ports during storage. Actuators must be cycled
every 90 days in storage or in operation. Actuators that do not
cycle in 90 days should have a provision to jog the actuator to
check for operation if a full cycle cannot be achieved.
5. Double Acting Operation
Applying air pressure to the CCW Port drives the piston
toward the front flange which turns the yoke counterclockwise
when viewed from the accessory
side of the actuator. When
pressure is applied to the CW Port the piston is driven towards
the end cap which turns the yoke clockwise. This is shown in
Figure 1
TABLE OF CONTENTS
SECTION DESCRIPTION
1
INSTALLATION OF ACTUATOR
2
AIR SUPPLY
3
LUBRICATION
4
STORAGE OF ACTUATORS/ INFREQUENTLY CYCLED
5
DOUBLE ACTING OPERATION
6
SPRING RETURN OPERATION
7
TRAVEL ADJUSTMENT
8
REPLACEMENT OF CYLINDER SEALS
9
CONVERTING FROM DOUBLE ACTING
TO SPRING RETURN
10
CONVERTING FROM FAIL CLOSED TO FAIL OPEN
11
SEAL KIT AND REPAIR PARTS
12
BILL OF MATERIALS
