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L404F,T,V PRESSURETROL
®
CONTROLLERS
71-2429—2 6
Fig. 8. L404T,V terminal blocks and internal schematics.
Fig. 9. Hookup of an oil pressure controller used on a
single burner system with an integral oil pump.
Fig. 10. Hookup of an oil pressure controller used on a
single burner or multiburner system with an external oil
pump.
SETTINGS AND ADJUSTMENTS
When the pressure at the control rises above the L404
setpoint, a circuit opens between the R-B terminals. During a
pressure fall, R-B will close at the setpoint pressure minus the
switch differential.
For example, if a controller is set to differential B (see Fig.11)
with a controller setpoint of A, R-B will open when the
pressure rises to A. Then during a pressure fall, the R-B
terminals will close when the pressure drops to C (A minus
differential B).
For make on rise applications, the switch is wired to R-W
terminals. The R-W circuit will close on pressure rise to the
setpoint. R-W will open again on a pressure drop past the
switch differential.
Fig. 11. Operation of switch on pressure rise and fall.
Setpoint Adjustment
Turn the pressure adjusting screw on the top of the controller
(Fig. 12) to adjust the setpoint. Turn the differential adjusting
screw to the desired pressure difference between switch
opening and switch closing.
NOTE: When the main scale setting is at the lower end of
the operating range, the differential range will be less
than the differential setting by approximately 20
percent.
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.
L404T
BREAKS ON PRESSURE
RISE TO SET POINT
L404V
MAKES ON PRESSURE
RISE TO SET POINT
M1801B
B
R
W
R
W
B
(OMITTED)
L2
OIL PRESSURE
CONTROLLER
MAIN OIL VALVE
SOLENOID
FLAME
SAFEGUARD
CONTROL
M9789
L2
L2
L1
(HOT)
OIL PRESSURE
CONTROLLER
FLAME
SAFEGUARD
CONTROL
OTHER
CONTROLLERS,
LIMITS, AND
INTERLOCKS
M9790
M19639B
B-R MAKES
(R-W BREAKS)
DIFFERENTIAL
(ADJUSTABLE)
B-R BREAKS
(R-W MAKES)
CONTROL
SET POINT
B R-W
B-R
SWITCH ACTION ON
PRESSURE RISE
INDICATES CLOSED SWITCH CONTACTS.
W
B-R
SWITCH ACTION ON
PRESSURE FALL
W
B R-W
GROUND SCREW
DIFFERENTIAL
A
DJUSTING SCREW
SCALEPLATES
DIAPHRAGM
ASSEMBLY
M19640A
OPERATING
LEVER
MAIN SCALE
PRESSURE
INDICATOR
DIFFERENTIAL
SETTING
INDICATOR
PRESSURE ADJUSTING SCREW