Drawing Number: 21167
Revision: NR
OPERATION MANUAL FOR
ICP
WATER-COOLED PRESSURE SENSORS
MODELS 124A21, A22, A24
2
The Models 124A21, A22 and A24 sensors use
low output impedance probes (ICP
) and will
not require the extreme insulation resistance
precaution commonly associated with charge
mode sensors.
Connect the sensor cable to the appropriate
ICP
power unit and check the front panel
monitor
meter
for
continuity
of
cable
connections and internal amplifier.
Consult Guide G-0001B, "General Guide to
ICP
Instrumentation" for installation and usage
hints
for ICP
instruments
.
4.0
OPERATION
Consult Guide G-0001B for a complete
description of the low-impedance concept in
instrumentation.
All PCB power units designed for ICP
sensors
use contain built-in fault monitor meters to aid
in locating circuit faults (shorts or opens) and to
identify normal operation of the miniature
impedance converting amplifier built into the
sensor.
Do not attempt to apply voltage directly to the
input pin of the sensor from any other source.
The input current must be limited to 20 mA
maximum and the input voltage must not be
higher than 30 volts. If it is desired to build a
power unit, rather than to use one of those
available from PCB, contact the factory for
approval of this change.
The Models 124A21, 124A22 and 124A24 are
identical except for sensitivity.
The Model 124A21 has a sensitivity of 20
mV/psi which gives a full-scale range (for
5%
out) of 250 psi.
The Model 124A22 has a sensitivity of 1.0
mV/psi and a full-scale range of 5000 psi.
The Model 124A24 has a sensitivity of 5.0
mV/psi and a full-scale range of 1000 psi.
5.0
CALIBRATION
Because of the shorter time constants built into
these models, static calibration methods are
difficult to employ.
Pressures must be applied rapidly and readout
must be made with fast recording devices such
as storage oscilloscopes or similar types of data
acquisition hardware.
A pneumatic (compressed air) system with
quick opening valve and reference gage is an
excellent method of calibrating these sensors.
To take full advantage of the time constant built
into the sensor, use a DC-coupled power unit
such as the PCB Model 484B.
6.0
MAINTENANCE
The sealed construction and miniature size of
these sensors make field repair impractical.
Contact factory for assistance should problems
arise.
ICP is a registered trademark of PCB
Piezotronics
