IOM-VM-C: JUN 2022
www.delta-mobrey.com Page 4 of 7
Operation
Adjustments
Pressure Switches are supplied to a midscale
falling, unless otherwise specified.
If the instrument has been ordered with a
specific calibration value the adhesive label
shows the set point value.
It is a good rule to check the calibration values
are marked on the relevant adhesive label,
prior to installation.
Earthing connections
Warning: The instrument is supplied with two
protective grounding connections, one inside
and one outside the enclosure. The two
connections provide effective connection to a
conductor with a cross-sectional area of at
least 4 mm2.
Warning: In order to protect the instrument
against extreme environmental conditions, a
coating thicker than 0.2 mm should be
applied. The grounding connection has to be
adequately realised to prevent an
electrostatic surcharge on the instrument
surface. CLEAN ONLY with a damp cloth
Calibration
Please follow the below suggested steps to
calibrate the set point of the instrument:
Connect the instrument to the pneumatic tools
in the normal installation position (see Fig.1).
Loosen the lid lock screw and unscrew the lid.
Connect the warning lamp appropriately.
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 increase 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. Using a suitable
spanner (Ch 13), rotate the range adjuster
clockwise to increase the set point and counter
clockwise to decrease the set point up to the
relative lamp turn ON (or OFF).
Go to the normal operating pressure and
increase (or decrease) the pressure up the
relative lamp turn ON (or OFF). Read the
pressure on the test gauge. Eventually adjust
the range adjuster and re-check again using
the lamp until the set point is achieved with the
required accuracy.
Close the instrument lid and tighten lid lock
screw.
Write the set point on the adhesive label
Caution: The microswitch is factory set and
should not be adjusted. Should these parts be
accidentally loosened, please contact Delta
Mobrey for assistance.
Periodical calibration check
Connect the instrument to the pneumatic tools
in the normal installation position (see Fig.1).
Loosen the lid lock screw and unscrew the lid.
Connect the warning lamp according to the
desired function.
Set point calibrated with increasing
pressure
On atmospheric pressure, pressurise the
circuit and slowly increase the pressure up to
the set point (the warning lamp turns ON).
Record the pressure read out on the test
gauge. Return to atmospheric pressure.
Repeat the above operation twice.
Set point calibrated with decreasing
pressure
On atmospheric pressure, pressurise the
circuit up to the upper range value.
Decrease the pressure slowly up to the set
point (the warning lamp turns ON).
Record the pressure read on the test gauge.
Return to 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 find the maximum difference
of the detected set point values
If the average set point is different from the
expected setpoint, the instrument must be
recalibrated.
If the repeatability is higher than the value in
the Technical Data Sheet of the product,
replace the instrument with a new one and
contact the factory.
End of verification
Remove the instrument from the pneumatic
tool and disconnect the warning lamp
Close the instrument lid and tighten the lid lock
screw.
