Product Manual - PCB Piezotronics
Model 121A23
ICP® Pressure Sensor
Installation and Operating Manual
For assistance with the operation of this product,
contact PCB Piezotronics, Inc.
Toll-free: 800-828-8840
24-hour SensorLine: 716-684-0001
Fax: 716-684-0987
E-mail: [email protected]
Warranty, Service, Repair, and
Return Policies and Instructions
The information contained in this document supersedes all similar information that
may be found elsewhere in this manual.
Total Customer Satisfaction – PCB
Piezotronics guarantees Total Customer
Satisfaction. If, at any time, for any
reason, you are not completely satisfied
with any PCB product, PCB will repair,
replace, or exchange it at no charge. You
may also choose to have your purchase
price refunded in lieu of the repair,
replacement, or exchange of the product.
Service – Due to the sophisticated nature
of the sensors and associated
instrumentation provided by PCB
Piezotronics, user servicing or repair is
not recommended and, if attempted, may
void the factory warranty. Routine
maintenance, such as the cleaning of
electrical connectors, housings, and
mounting surfaces with solutions and
techniques that will not harm the
physical material of construction, is
acceptable. Caution should be observed
to insure that liquids are not permitted to
migrate into devices that are not
hermetically sealed. Such devices should
only be wiped with a dampened cloth
and never submerged or have liquids
poured upon them.
Repair – In the event that equipment
becomes damaged or ceases to operate,
arrangements should be made to return
the equipment to PCB Piezotronics for
repair. User servicing or repair is not
recommended and, if attempted, may
void the factory warranty.
Calibration – Routine calibration of
sensors and associated instrumentation is
recommended as this helps build
confidence in measurement accuracy and
acquired data. Equipment calibration
cycles are typically established by the
users own quality regimen. When in
doubt about a calibration cycle, a good
“rule of thumb” is to recalibrate on an
annual basis. It is also good practice to
recalibrate after exposure to any severe
temperature extreme, shock, load, or
other environmental influence, or prior
to any critical test.
PCB Piezotronics maintains an ISO9001 certified metrology laboratory and
offers calibration services, which are
accredited by A2LA to ISO/IEC 17025,
with full traceablility to N.I.S.T. In
addition to the normally supplied
calibration, special testing is also
available, such as: sensitivity at elevated
or cryogenic temperatures, phase
response, extended high or low
frequency response, extended range, leak
testing, hydrostatic pressure testing, and
others. For information on standard
recalibration services or special testing,
contact your local PCB Piezotronics
distributor, sales representative, or
factory customer service representative.
Returning Equipment – Following
these procedures will insure that your
returned materials are handled in the
most expedient manner. Before returning
any equipment to PCB Piezotronics,
contact your local distributor, sales
representative, or factory customer
service representative to obtain a Return
Number. This RMA number should be
clearly marked on the outside of all
package(s) and on the packing list(s)
accompanying the shipment. A detailed
account of the nature of the problem(s)
being experienced with the equipment
should also be included inside the
package(s) containing any returned
PCB for a complete statement of our
warranty. Expendable items, such as
batteries and mounting hardware, are not
covered by warranty. Mechanical
damage to equipment due to improper
use is not covered by warranty.
Electronic circuitry failure caused by the
introduction of unregulated or improper
excitation power or electrostatic
discharge is not covered by warranty.
A Purchase Order, included with the
returned materials, will expedite the
turn-around of serviced equipment. It is
recommended to include authorization
on the Purchase Order for PCB to
proceed with any repairs, as long as they
do not exceed 50% of the replacement
cost of the returned item(s). PCB will
provide a price quotation or replacement
recommendation for any item whose
repair costs would exceed 50% of
replacement cost, or any item that is not
economically feasible to repair. For
routine calibration services, the Purchase
Order should include authorization to
proceed and return at current pricing,
which can be obtained from a factory
customer service representative.
Contact Information – International
customers should direct all inquiries to
their local distributor or sales office. A
complete list of distributors and offices
can be found at
Customers within the United States may
contact their local sales representative or
representative. A complete list of sales
representatives can be found at Toll-free telephone
numbers for a factory customer service
responsible for this product, can be
found on the title page at the front of this
manual. Our ship to address and general
contact numbers are:
Warranty – All equipment and repair
services provided by PCB Piezotronics,
Inc. are covered by a limited warranty
workmanship for a period of one year
from date of original purchase. Contact
ECN: 17900
PCB Piezotronics, Inc.
3425 Walden Ave.
Depew, NY 14043 USA
Toll-free: (800) 828-8840
24-hour SensorLineSM: (716) 684-0001
E-mail: [email protected]
Series 121
Models 121A21, 121A22, 121A23, 121A24
Models 121A31, 121A32, 121A33, 121A34
The Series 121 consists of eight ruggedized quartz
sensors designed for dynamic pressure measurements
in harsh environments. Models 121A21-24 have twopin MIL connectors, and Models 121A31-34 are
provided with a molded integral cables, 10 feet (3 m)
The high impedance voltage signal produced by the
quartz element in the Series 121 is impressed across
the input of a built-in miniature source follower
amplifier (actually an impedance converter with unity
voltage gain) which converts the signal a low
impedance voltage less than 100, able to be fed
directly into readout instruments such as
oscilloscopes, peak meters, etc. over long cables.
Series 121 are designed for permanent installation by
Original Equipment Manufacturers in pumps,
compressors and pipelines for monitoring pressure
fluctuations and/or surges.
Series 121A30 Industrial Pressure Sensor
The models are dimensionally the same, and are
designed to cover a pressure range from 125 to
10,000 psi. The temperature range is from
-100 to 275F (-73 to 135C).
See the installation drawing at the front of this manual
for dimensional details of the Series 121A20 and
The Series 121A20 and 121A30 have an integral
housing diaphragm machined in stainless steel. The
sensor incorporates ¼ NPT mounting, and terminates
in either a two-pin MIL or integral cable.
Series 121A20 Industrial Pressure Sensor
Drawing Number: 21088
Revision: NR
Quartz plates are stacked in a thickness compression
mode to produce a relatively high natural frequency.
When pressure is applied to the diaphragm of the
sensor, the quartz element produces a high impedance
voltage signal which the miniature amplifier converts
to a low impedance level voltage (100 ) which can
Series 121
Models 121A21, 121A22, 121A23, 121A24
Models 121A31, 121A32, 121A33, 121A34
be read out on an oscilloscope or digital voltmeter.
Power to operate the integrated circuit amplifier and
the output signal are both conducted over a single
coaxial cable.
When the source terminal at the IC amplifier receives
a 2 to 20mA constant current from a +18 to 24VDC
supply the amplifier bias at the source will be +11
volts (nominal) and independent of supply voltage or
current. The output voltage signal from the quartz
element is added to the bias voltage at the source
terminal (See General Guide to ICP Signal
Conditioning, G-0001).
For details of mounting hole preparation, refer to the
installation drawing accompanying this manual.
Stay within the recommended torque range [(5-7 ftlbs (0.6-0.8 Nm)] when mounting the sensor. It is
advisable to use pipe joint compound to assure a tight
If a PCB signal conditioner is being used, turn the
power on and observe the voltmeter (or LED’s) on
the front panel. Typical indicators are marked as
shown in the figure below.
The green area (or LED) indicates the proper bias
range for the ICP sensor and the correct cable
connectors. A red color indicates a short condition in
the sensor, cable or connections. Yellow means the
excitation voltage is being monitored and is an
indication of an open circuit.
Use good machining practice in preparing the
mounting port. Make sure the seal surface is free of
tool chatter marks.
Note: Most PCB pressure sensors have an output
bias of 8-14 V. Refer to the specification sheet in this
manual for the bias range of the model you are using.
If you are using a low bias sensor, the indicator will
be at the bottom end of the green portion of the dial
indicator, and may even be in the red portion. This is
the expected range and indicates proper operation.
Note: Nicks, scratches, or other discontinuities in
the surface can cause leaks at high pressures.
Allow the instrument to warm up and thermally
When the output from the power unit is connected to
readout instrument, a signal drift will be noticed.
This drift is due to charging of the coupling capacitor
in the power unit and will cease within several
Series 121A20 has an integral 2-pin MIL connector.
Connect one end of an industrial cable to the sensor
and the other to the sensor input jack on an ICP
sensor signal conditioner (or equivalent). Series
121A30 is provided with an integral twisted pair
cable (red is signal, blue is GND). This can be
conveniently connected to a terminal strip on an ICP
compatible data acquisition system or can be ordered
with a BNC connector to connect to an ICP sensor
signal conditioner (or equivalent).
Drawing Number: 21088
Revision: NR
Series 121
Models 121A21, 121A22, 121A23, 121A24
Models 121A31, 121A32, 121A33, 121A34
1. Place sensor on test fixture with coaxial cable
connected to oscilloscope.
Typical ICP Connection
The 121 Series Pressure Sensors produce a positivegoing output voltage in response to pressure on the
The discharge time constant of the Series 121 is too
short to allow calibration of the sensor by static
means. The 121 series can, however, be calibrated by
dynamic means using a pulse calibrator such as the
Model 903B02. By this method, the sensor is
subjected to a series of calibrated step changes in
which a linear graph can be plotted over the full range
of the unit.
PCB provides recalibration service on request. If
such service is needed or desired, consult the factory
for details.
Four sensors in the 121 Series (121A21, 121A22,
121A23, and 121A24) have discharge time constants
of sufficient duration (100 secs.) to use dead weight
testers for calibration.
Apply known pressure to sensor diaphragm
(within range of instrument) using dead weight.
3. Remove weight and read change in output voltage
(mV) corresponding to input pressure (psi).
Repeat Steps 2 through 4 in 20% increments
within range of sensor.
5. Plot readings on x-y graph (voltage on the y-axis
verses pressure on the x-axis).
6. The slope of the line and the sensor sensitivity is
1. To avoid destroying the built-in amplifier, do not
apply a voltage to the sensor without a current
limiting device (20 mA maximum) in the line such
as those incorporated in all PCB units.
2. Do not subject sensor to temperatures exceeding
250°F (121°C).
3. Do not exceed maximum pressure rating.
Following is a brief laboratory procedure for
calibrating a pressure sensor using dead weights.
®ICP is a registered trademark of PCB Group
Drawing Number: 21088
Revision: NR
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