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L404F,T,V PRESSURETROL
®
CONTROLLERS
7 71-2429—06
Fig. 12. view of L404 PressureTrol
®
Controller.
Scaleplate Adjustment
The L404F,T,V has been carefully calibrated during
manufacture and should not require recalibration.
However, if recalibration is necessary, remove the cover and
loosen the setscrews which hold the scaleplate. Adjust the
plate up or down, as required, to bring the device into
calibration. Tighten the setscrews securely and replace the
cover.
CHECKOUT
After the controller has been installed, wired and adjusted, it
should be tested with the system in operation. First, allow the
system to stabilize. Then, observe the operation of the
controller while raising and lowering its setpoint. Pressure
should increase when the setpoint is raised and decrease
when the setpoint is lowered.
Also, check the make and break points of the controller. If they
do not agree with a separate, accurately calibrated pressure
gauge, a slight adjustment of the scaleplate(s) may be
necessary.
Use accurate pressure testing equipment when checking out
the controller. Do not rely on inexpensive gauges. The
controllers are carefully calibrated at the factory.
GROUND SCREW
DIFFERENTIAL
A
DJUSTING SCREW
SCALEPLATES
DIAPHRAGM
ASSEMBLY
M19640A
OPERATING
LEVER
MAIN SCALE
PRESSURE
INDICATOR
DIFFERENTIAL
SETTING
INDICATOR
PRESSURE ADJUSTING SCREW