Leslie Controls DOT 3-WAY CONTROL VALVE - Manual (Page 9)

9
4. CONTROL VALVES WITH DIRECT
ACTING ACTUATORS
(AIR PRESSURE MOVES VALVE PLUG
STEM DOWNWARD.)
a. Screw valve plug stem upward into actuator stem
until valve plug contacts upper seat.
b.
Connect air line to actuator. Supply sufficient air
pressure to move valve plug slightly away from
seat.
c. Then turn valve plug stem one full turn further
into actuator stem to make positive compression
contact of valve plug with upper seat at rated
travel.
d. Tighten stem nut and travel indicator against
actuator stem. Tighten package flange bolts.
5. CONTROL VALVE WITH REVERSE
ACTING ACTUATORS (AIR PRESSURE
MOVES VALVE PLUG STEM UPWARD.)
a. Screw valve plug stem upward into actuator stem
approximately one diameter (thickness of stem.)
b.
Connect air line to actuator. Supply 20 psig air
pressure to actuator diaphragm to move actuator
through full travel.
c. Turn valve plug stem upward into actuator stem
until valve plug contacts upper seat.
d. Reduce air pressure on diaphragm to permit valve
plug to move slightly off seat.
e. Then turn valve plug stem one full turn further
into actuator stem to make positive compression
contact with upper seat at rated travel.
f. Tighten stem nut and travel indicator against
actuator stem. Tighten packing flange bolts.
6. SHORT VALVE TRAVEL
If valve travel is too short when required maximum air
pressure is supplied to actuator diaphragm, incorrect
adjustment is indicated. To correct, loosen stem nut and
turn valve plug stem out of actuator stem amount
necessary to obtain full travel. Travel indicator on yoke
shows full travel. Recheck positive compression force then
tighten stem nut.
NOTE: In 21/2” and larger bronze valve ONLY, the
bonnet is of a two piece construction. Be sure to replace
the caution plate (1”-2” valves) before mounting the
actuator.