Honeywell L404T Manuel D’Utilisation

7

71-2429—06

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.

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

ADJUSTING SCREW

SCALEPLATES

DIAPHRAGM

ASSEMBLY

M19640A

OPERATING

LEVER

MAIN SCALE

PRESSURE

INDICATOR

DIFFERENTIAL

SETTING

INDICATOR

PRESSURE ADJUSTING SCREW