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IOM-CS-F: AUG 2022
Operation Adjustments
Pressure switches are supplied and adjusted
at midscale falling, unless otherwise specified.
If the instrument has been ordered with
specific calibration values the adhesive label
shows the set point values.
It is a good rule to check the calibration values
marked on the relevant adhesive label, prior to
installation.
Calibration
Please follow the suggested steps below to
calibrate the set point of the instrument:
Connect the instrument to the pneumatic tools
in the normal installation position (see Fig.1).
If the instrument is supplied with a Junction
box, slacken the lid lock screw and unscrew
the lid. Connect the warning lamp according
the desired function.
Caution: Do not attempt to set the switch
outside the scale limits.
Though the unit may be set anywhere within
its range, for optimum performance, it is good
practice to have a set point value between
25% and 75% of span.
Connection C-NO terminal
- The circuit is open at the normal operating
pressure, the switch closes the circuit as the
pressure increases when the desired value is
reached
- The circuit is closed at the normal operating
pressure, the switch opens the circuit as the
pressure decreases when the desired value
is reached
Connection C-NC terminal
- The circuit is closed at the normal operating
pressure, the switch opens the circuit as the
pressure increases when the desired value is
reached
- The circuit is open at the normal operating
pressure, the switch closes the circuit as the
pressure decreases when the desired value
is reached
Pressurise the circuit and slowly increase the
pressure up to the set point.
Slide the cover upwards.
Using a screwdriver, rotate the range adjuster
right to left to increase the set point and left to
right to decrease the set point until the relative
lamp is turned ON, or OFF.
As a guide, one complete revolution of the
adjuster will alter the set point by
approximately 15% of the range.
Go to the normal operating pressure and
increase (or decrease) the pressure until the
relative lamp turn ON or OFF. Read the
pressure on the test gauge. Gradually adjust
the range adjuster and recheck again using
the lamp until the set point is achieved with the
required accuracy.
Slide the cover downwards.
Write the set point on the adhesive label
Periodical calibration checks
Connect the instrument to the pneumatic tools
in the normal installation position (see Fig.1).
Connect the warning lamp according to the
desired function.
Set point calibrated with increasing
pressure
From atmospheric pressure, pressurise the
circuit and increase the pressure up slowly to
the set point (the warning lamp is shown as
ON).
Record the pressure read on the test gauge.
Return to atmospheric pressure.
Repeat the above operation twice.
Set point calibrated with decreasing
pressure
From atmospheric pressure, pressurise the
circuit up to upper range value.
Decrease the pressure down slowly to the
set point (the warning lamp switches ON).
Record the pressure read it on the test
gauge.
Return to the upper range pressure value.
Repeat the above operation twice.
Evaluation of set point value and
repeatability
With all the above values detected, calculate:
- Average set point value
- Repeatability correspondent to the max
difference of the detected set point values.
If the average set point is different from the
expected, the instrument must be recalibrated.
If the repeatability is higher than the value in
the product Technical Data Sheet replace the
instrument with a new one and contact the
factory.
End of verification
Fig. 7 - Set point adjusting
