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14
THE
PROBES
The HD21...4.0 and HD21...4.2 instruments
are fitted with differential pressure sensor
compared to the atmosphere
of 20mbar (models HD2114), 200mbar (models HD2134) and
2000mbar (models HD2164). The HD2114B.0 and HD2114B.2 models measures the barometric
pressure in the 600…1100mbar range.
The coupling on the left is positive (+), on the right negative (-): for relative measurements
compared to atmosphere, apply the pressure to the positive input and leave the negative input open.
Important
:
the nominal bottom scales of internal sensors (20, 200, 2000mbar and 1100mbar)
are referred to atmospheric pressure
,
therefore on each of these inputs no relative pressure
exceeding the maximum stated overpressure should be applied. Each of the two sensor inputs can
bear without breaking–but without measuring–the overpressures reported in the following table:
HD2114.0
HD2114.2
HD2134.0
HD2134.2
HD2164.0
HD2164.2
HD2114B.0
HD2114B.2
Measurement range
20mbar
200mbar
2000mbar
600..1100mbar
Maximum overpressure
300mbar
1bar
6bar
3bar
In addition to the internal sensor, it is possible to measure absolute, relative and differential pressure
using the PP471 SICRAM module and the TP704 and TP705 series probes. The peak measurement
is enabled using these probes.
To change the instantaneous or peak value unit of measurement, press UNIT. The following units of
measurement are available:
Pa, hPa, kPa, mbar, bar, atm, mmHg, mmH
2
O, kgf/cm
2
, PSI, inchHg.
Some units of measurement require a multiplication factor: the “-3” symbol indicates the displayed
value must be divided by 1,000; the "3" and "6" symbols indicate the displayed value must be
multiplied respectively by 1,000 or by 1,000,000.
All models measure also the temperature using probes fitted with SICRAM module and with
temperature probes with 4-wire Pt100, 2-wire Pt1000 or Ni1000 sensors.
In the probes fitted with SICRAM module the latter acts as an interface between the sensor on the
probe and the instrument. There is a microprocessor circuit with a permanent memory inside the
module that enables the datalogger to recognize the type of probe connected and to read its
calibration information.
The temperature probes without SICRAM module are not automatically detected by the instrument
and must be set up in the
Probe type
menu item (please see the description of the menu on page
The probes are detected during turn on, and this cannot be performed when the instrument is
already on, therefore if a probe is connected and the instrument is on, it is necessary to turn it
off and on
.
The probes are fitted with SICRAM module are calibrated in the factory; no calibration is required
by the user.