Drawing Number: 21110
Revision: B
OPERATION MANUAL FOR
QUARTZ PRESSURE SENSOR
Series 118 & 119
4
5.0
OPERATION
Most test set-ups will include 118 & 119 Series
sensors coupled with charge amplifiers, as shown in
the
Typical
Connection
figure
below.
For
applications where the location of the measurement is
a long distance from where the data must be read, an
in-line amplifier can be used to drive the signal. This
configuration reduces the amount of noise in the data
and can be seen in the Long Distance Connection
figure to the right.
It is important to keep the charge amplifier input
cable as short as practical. Input cable capacitance is
directly related to cable length and is a major factor
in the amount of electrical noise at the output of any
charge amplifier.
Depress the ground button of the charge amplifier and
adjust electrical zero if necessary. Range the
amplifier as required to give the necessary full-scale
voltage.
For normal, drift-free operation, switch the charge
amplifier time constant selector to “medium” or
“short” during use.
Typical Connection
6.0
POLARITY
Since most charge amplifiers are inverting the input
signal, 118 & 119 Series are designed to produce a
negative output voltage for increasing pressure at the
diaphragm.
Special positive output versions are available for use
with our non-inverting ICP
®
source follower
amplifiers.
ICP
®
is a registered trademark of PCB Piezotronics
Long Distance Connection
7.0
MAINTENANCE
Regular inspection of the diaphragm, threads, and
connector of the 118 & 119 Series sensors is good
practice.
During use in damp environments or after a period of
storage, the insulation resistance of these sensors may
degrade (10
12
ohms is normal). The only maintenance
required on the 118 & 119 Series is cleaning of the
connector to restore insulation resistance.
To restore insulation resistance, wipe the connector
end with a clean cloth or paper towel dipped in
Lenium
®
or an equivalent solvent, then rinse in
isopropyl alcohol. The sensor should then be placed
in a 250
F (120
C) oven for several hours. A
vacuum oven, if available, will speed the process.
Contact the factory for further assistance if the
insulation resistance cannot be restored.
IN-LINE
AMPLIFIER
118 & 119
SERIES
LOW-NOISE CABLE
ICP
®
POWER SUPPLY
READOUT
COAXIAL
CABLE
118 & 119
SERIES
READOUT
LOW-NOISE CABLE
CHARGE
AMPLIFIER
COAXIAL
CABLE
