Leslie Controls Pilot Controller - Manual (Page 7)

Page 7
STEM LENGTH AND SENSITIVITY ADJUSTMENT
TYPES PRA-1 AND PRQ-1
CONSTANT PRESSURE PILOT CONTROLLERS
FORCE BALANCE, FIXED BAND TYPES
ADJUSTMENT PROCEDURE
Supply 20-22 psig operating pressure to the pilot controller.
Turn adjusting nut to compress adjusting spring to set upper
diaphragm against its top limit stop. If possible remove fluid
pressure from top of diaphragm, if not compress springs suffi-
ciently to overcome fluid pressure and move diaphragm to
stop.
ADJUSTING RESPONSE SENSITIVITY
Remove nozzle disc pin, pilot cover and diaphragm nozzle
disc.
For Normal Response Sensitivity adjust pilot controller for
very minor or no leak off. To do this relieve pressure of blade
spring on nozzle stop by pressing lightly downward on it with
finger. Then screw nozzle stop downward until it is felt to bare-
ly seat on nozzle nut.
For Supersensitive Response adjust pilot controller for con-
tinuous leak off. To do this slowly screw nozzle stop further
downward until operating pressure flow is just detectable
through nozzle bleed port. To check amount of leak off place
finger lightly over nozzle bleed port to seal air (do not press
down on nozzle). Air pressure in output line to diaphragm con-
trol valve should not build up any faster than 3-5 psig in 20-30
seconds. Lock nozzle stop with blade spring.
To Test Pilot Controller Body and Diaphragm Control Valve
for response press downward on center of nozzle until 20-22
psig air pressure registers on output gauge. Control valve
should move through full travel. Release nozzle. Air output
pressure should drop to 0 psig and control valve should return
to its original position.
After completing sensitivity adjustment replace diaphragm
nozzle disc, nozzle disc pin and pilot cover.
LEVER SCREW ADJUSTMENT
Desired pilot controller performance will be obtained only if the
upper (sensing) diaphragm is operating at or near its mean
position, i.e. half way between its top and bottom limit stops in
base and cover. Its position is determined by adjusting length
of lever adjusting screw.
NOTE: THIS ADJUSTMENT IS FACTORY SET and should
not be disturbed unless it is obvious that the original setting
has been changed or major parts replacements were made
which may cause need for readjustment.
These adjustments can be made when the pilot controller is
set for either continuous or non-continuous leak off.
PRA-1 AND PRQ PILOT CONTROLLERS
1. Loosen locknut on lever setscrew. With 20 psig air pres-
sure on out put gauge turn setscrew upward into lever
until output air pressure just begins to fall away from 20
psig.
2. Then turn lever screw downward (out of lever) 3/4 turn
for all low pressure pilots (up to and including the 50-125
psig range) 1-1/4 turns for high pressure ranges (100-
200) psig and over). Tighten locknut.
NOTE: With pilot air output at 20/22 psig, lever should be
approximately in the parallel position. If not parallel loosen
nozzle disc pin locknut and screw lower section of pin into or
out of upper section of pin until lever is parallel. Tighten lock-
nut.
Figure 11. PRA-1, PRW-1, PRQ, Pilot Controllers