PCB Piezotronics 122A21 User manual

Model 122A21
Rocket motor ICP® pressure sensor, 250 psi, 20 mV/psi, Helium bleed, conical end seal
Installation and Operating Manual
For assistance with the operation of this product,
contact the PCB Piezotronics, Inc.
Toll-free: 716-684-0001
24-hour SensorLine: 716-684-0001
Fax: [phone]
E-mail: [email protected]
Web: www.pcb.com

Manual 21354 Rev E
ECN 50523
Repair and Maintenance
PCB guarantees Total Customer Satisfaction through its
“Lifetime Warranty Plus” on all Platinum Stock Products
sold by PCB and through its limited warranties on all other
PCB Stock, Standard and Special products. Due to the
sophisticated nature of our sensors and associated
instrumentation, field servicing and repair is not
recommended and, if attempted, will void the factory
warranty.
Beyond routine calibration and battery replacements
where applicable, our products require no user
maintenance. Clean electrical connectors, housings, and
mounting surfaces with solutions and techniques that will
not harm the material of construction. Observe caution
when using liquids near devices that are not hermetically
sealed. Such devices should only be wiped with a
dampened cloth—never saturated or submerged.
In the event that equipment becomes damaged or ceases
to operate, our Application Engineers are here to support
your troubleshooting efforts 24 hours a day, 7 days a
week. Call or email with model and serial number as well
as a brief description of the problem.
Calibration
Routine calibration of sensors and associated
instrumentation is necessary to maintain measurement
accuracy. We recommend calibrating on an annual basis,
after exposure to any extreme environmental influence,
or prior to any critical test.
PCB Piezotronics is an ISO-9001 certified company whose
calibration services are accredited by A2LA to ISO/IEC
17025, with full traceability to SI through N.I.S.T. In
addition to our standard calibration services, we also offer
specialized tests, including: sensitivity at elevated or
cryogenic temperatures, phase response, extended high
or low frequency response, extended range, leak testing,
hydrostatic pressure testing, and others. For more
information, contact your local PCB Piezotronics
distributor, sales representative, or factory customer
service representative.
Returning Equipment
If factory repair is required, our representatives will
provide you with a Return Material Authorization (RMA)
number, which we use to reference any information you
have already provided and expedite the repair process.
This number should be clearly marked on the outside of
all returned package(s) and on any packing list(s)
accompanying the shipment.
Contact Information
PCB Piezotronics, Inc.
3425 Walden Ave.
Depew, NY14043 USA
Toll-free: [phone]
24-hour SensorLine: [phone]
General inquiries: in[email protected]
Repair inquiries: [e-mail]
For a complete list of distributors, global offices and sales
representatives, visit our website, www.pcb.com.
Safety Considerations
This product is intended for use by qualified personnel
who recognize shock hazards and are familiar with the
precautions required to avoid injury. While our equipment
is designed with user safety in mind, the protection
provided by the equipment may be impaired if equipment
is used in a manner not specified by this manual.
Discontinue use and contact our 24-Hour Sensorline if:
Assistance is needed to safely operate equipment
Damage is visible or suspected
Equipment fails or malfunctions
For complete equipment ratings, refer to the enclosed
specification sheet for your product.
Definition of Terms and Symbols
The following symbols may be used in this manual:
DANGER
Indicates an immediate hazardous
situation, which, if not avoided, may
result in death or serious injury.

Manual 21354 Rev E
ECN 50523
CAUTION
Refers to hazards that could damage
the instrument.
NOTE
Indicates tips, recommendations and
important information. The notes
simplify processes and contain
additional information on particular
operating steps.
The following symbols may be found on the equipment
described in this manual:
This symbol on the unit indicates that
high voltage may be present. Use
standard safety precautions to avoid
personal contact with this voltage.
This symbol on the unit indicates that
the user should refer to the operating
instructions located in the manual.
This symbol indicates safety, earth
ground.

Manual 21354 Rev E
ECN 50523
PCB工业监视和测量设备 - 中国RoHS2公布表
PCB Industrial Monitoring and Measuring Equipment - China RoHS 2 Disclosure Table
部件名称
有害物质
铅(Pb)
汞
(Hg)
镉
(Cd)
六价铬(Cr(VI))
多溴联苯 (PBB)
多溴二苯醚(PBDE)
住房
O
O
O
O
O
O
PCB板
X
O
O
O
O
O
电气连接器
O
O
O
O
O
O
压电晶体
X
O
O
O
O
O
环氧
O
O
O
O
O
O
铁氟龙
O
O
O
O
O
O
电子
O
O
O
O
O
O
厚膜基板
O
O
X
O
O
O
电线
O
O
O
O
O
O
电缆
X
O
O
O
O
O
塑料
O
O
O
O
O
O
焊接
X
O
O
O
O
O
铜合金/黄铜
X
O
O
O
O
O
本表格依据 SJ/T 11364 的规定编制。
O：表示该有害物质在该部件所有均质材料中的含量均在 GB/T 26572 规定的限量要求以下。
X：表示该有害物质至少在该部件的某一均质材料中的含量超出 GB/T 26572 规定的限量要求。
铅是欧洲RoHS指令2011/65/ EU附件三和附件四目前由于允许的豁免。
CHINA RoHS COMPLIANCE

Manual 21354 Rev E
ECN 50523
Component Name
Hazardous Substances
Lead (Pb)
Mercury (Hg)
Cadmium (Cd)
Chromium VI
Compounds
(Cr(VI))
Polybrominated
Biphenyls (PBB)
Polybrominated
Diphenyl Ethers
(PBDE)
Housing
O
O
O
O
O
O
PCB Board
X
O
O
O
O
O
Electrical Connectors
O
O
O
O
O
O
Piezoelectric Crystals
X
O
O
O
O
O
Epoxy
O
O
O
O
O
O
Teflon
O
O
O
O
O
O
Electronics
O
O
O
O
O
O
Thick Film Substrate
O
O
X
O
O
O
Wires
O
O
O
O
O
O
Cables
X
O
O
O
O
O
Plastic
O
O
O
O
O
O
Solder
X
O
O
O
O
O
Copper Alloy/Brass
X
O
O
O
O
O
This table is prepared in accordance with the provisions of SJ/T 11364.
O: Indicates that said hazardous substance contained in all of the homogeneous materials for this part is below the limit
requirement of GB/T 26572.
X: Indicates that said hazardous substance contained in at least one of the homogeneous materials for this part is above the limit
requirement of GB/T 26572.
Lead is present due to allowed exemption in Annex III or Annex IV of the European RoHS Directive 2011/65/EU.

Drawing number: 21089
Revision:A
ECO: 52570
OPERATION MANUAL FOR
122 SERIES
HELIUM BLEED PRESSURE SENSOR
1
1.0 INTRODUCTION
The series of sensors described in this guide are
designed to measure dynamic pressure in intense
thermal environments typified by rocket engine
combustion chambers.
These sensors feature acceleration-compensated
piezoelectric pressure probes, mounted in a conical end
seal helium bleed adaptor.
The helium gas, applied from a 1500 psi source, is
metered by a built-in orifice and flows around the probe
body and out the passage of the adaptor ahead of the
probe diaphragm. The helium gas flowing out the
passage protects the sensor diaphragm from the hot
gasses as well as increasing the natural frequency of the
passage by a factor of approximately three to one.
2.0 DESCRIPTION
The charge-mode models contain a one pC/psi pressure
probe (sensor) and is designed to be used with
electrostatic charge amplifiers.
The ICPModels contain built-in impedance converter
electronics circuits which convert the high-impedance
voltage from the quartz crystal to a low-impedance
voltage signal that can be fed directly into most
common indicating or recording instruments.
The 122 series sensors contain a 10 micron helium filter
contained in a fitting threaded onto the helium input
tube. The purpose of this filter is to prevent particles in
the helium supply from plugging the metering orifice.
The outer body of this series is 17-4 PH hardened
stainless steel and features a conical tip for sealing
without seal rings or washers. This feature also allows
the sensor sensing passage to be placed closer to the
chamber without a long passage that could cause
resonance problems, severely limiting high frequency
response.
122 Series: Helium Bleed Rocket Motor, ICP® and
Charge Sensors
NOTE: The sensor probe in this series is factory
installed at a precise depth in the outer body. Do not
attempt removal of this probe. Contact the factory
should any questions or problems arise concerning
the sensor probe.
The 122 Series Sensors use low output-impedance
probes (ICP®).
Connect the sensor cable to the appropriate ICP®
power unit and check the front panel monitor meter
to check cable connections and internal amplifier.
Consult Guide G-0001B, "General Guide to ICP®
Instrumentation" for installation and usage hints for
ICP®instruments.

Drawing number: 21089
Revision:A
ECO: 52570
OPERATION MANUAL FOR
122 SERIES
HELIUM BLEED PRESSURE SENSOR
2
3.0 INSTALLATION
Prepare mounting port in accordance with instructions
on the installation drawing.
Inspect the mounting port for burrs and tool marks at
the conical seal surface.
NOTE: A 75⁰ end-cutting reamer, Model 040A02, is
available from PCB. Contact the factory for price and
delivery information.
Use recommended mounting torque when installing
sensors. Do not over torque as damage to seal surface
could result.
NOTE: When attaching helium supply hose, do not
torque hose fitting through helium tube on sensor.
Back up fitting with wrench on 3/8 hex on helium
hose fitting. (Refer to note 3 on installation drawing.)
In the presence of high vibration, support helium supply
tube by clamping to rigid surfaces with adequate strain
relief loop to avoid stressing helium tube on sensor.
For charge-mode models, connect 4 ft. cable to charge
amplifier and switch to "long" time constant position
and check for drift.
Clean offending cable connections with
Trichloroethylene®or equivalent solvent to restore
insulation resistance.
It is good practice to depress ground button (or place
switch in GND" position) on the charge amplifier while
attaching input cables to the amplifier. This will
prevent spurious charges which may accumulate on
sensors and cables from blowing out the input circuitry
of the charge amplifier.
Since the charge output sensors are susceptible to
decreased insulation resistance, use care to keep cable
connections clean by use of shrink tubing wherever
possible.
4.0 OPERATION
4.1 CHARGE OUTPUT
For the 122 Series, it is only necessary to select the
proper range on the charge amplifier and proceed
with the measurement.
The probe sensitivity is approximately 1.0 pC/psi. (The
exact sensitivity is given on the calibration
certificate supplied with each instrument.)
EXAMPLE: The dynamic pressure expected is 500
psi and the desired output voltage for this pressure is
1 volt.
Simply set the range switch of the charge amplifier to
500 units per volt and dial the standardization pot to
the exact sensor sensitivity at 500 psi (from
calibration graph). The system will then yield exactly
1 volt for 500 psi of input pressure.
4.2 TIME CONSTANT
During in-place calibration, static methods (dead
weight tester) may be used in a drift-free system by
placing the charge amplifier in "LONG TC" position.
However, during actual use, the TC mode switch should
be in "SHORT" position for two reasons.
Often times, the dynamic pressure being measured
exists superimposed upon a higher static level. The
short TC position will allow the effect of this static
level to zero out quickly without effect on the
dynamic level indicated.
Also, the influx of large amounts of thermal energy,
as in rocket combustion measurements, can cause the
sensor to generate spurious transient outputs of
considerable magnitude. Using the charge amplifier
on SHORT TC alleviates this problem by shunting
these longer term charge outputs to ground while
measuring the faster dynamic pressure pulses.

Drawing number: 21089
Revision:A
ECO: 52570
OPERATION MANUAL FOR
122 SERIES
HELIUM BLEED PRESSURE SENSOR
3
4.3 OPERATION - ICP®MODELS
Consult Guide G-0001B for a complete description of
the low-impedance concept in instrumentation.
All PCB power units designed for ICP®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 power source. The input
current must be limited to 20 mA maximum and the
input voltage must not be higher than 35 VDC. Consult
the factory if it is desired to build a power unit rather
than to use one of those available from PCB.
NOTE: Full-scale range is limited by the helium source
pressure. The applied helium source pressure level must
be at least twice the peak combustion pressure (not to
exceed 15,000 psi), and not more than 10 times the
lowest expected peak combustion pressure. This is true
for all models, charge or ICP®.
5.0 CALIBRATION
5.1 CHARGE MODEL
To calibrate this model, install in pressure port of
dead weight tester and apply various static pressures
recording corresponding outputs at each pressure of
interest.
Discharge the charge amplifier before each reading
and return pressure to zero before each new pressure
input.
Use the charge amplifier on "LONG" time constant and
keep cables and connections clean to avoid drift.
A D.C. digital voltmeter is ideal for readout during
calibration.
NOTE: The helium tube must be plugged with a
pressure-tight seal before attempting to calibrate to
avoid losing pressure through the helium tube.
If a hydraulic calibration system is used, be sure to
remove all traces of oil from the diaphragm passage.
5.2 ICP®MODELS
Because of the shorter time constants built into these
models, static calibration methods are much more
difficult to use.
Pressure must be applied rapidly and readout must be
made with fast recording devices such as light storage
oscilloscopes or similar types of data acquisition
hardware.
A pneumatic (compressed air or hydrogen) system
with quick opening valve and reference gage is an
excellent method of calibrating these sensors.
6.0 GROUND ISOLATION
All sensor probes in this series are mounted in an "OFF
GROUND" configuration. That is, the probe body is
electrically insulated from the sensor outer body to
avoid ground loops.
7.0 MAINTENANCE AND REPAIR
The sealed construction and miniature size of these
sensors make field repair impractical.
The helium filter element should be cleaned should the
flow rate decrease. Remove the element and
ultrasonically agitate in solvent for 15 minutes, then
dry.
Should the orifice become plugged, back pressure the
orifice by applying air pressure to diaphragm end of
sensor with filter off and helium tube vented to
atmosphere.

Drawing number: 21089
Revision:A
ECO: 52570
OPERATION MANUAL FOR
122 SERIES
HELIUM BLEED PRESSURE SENSOR
4
The only maintenance possible on the probe is the
maintaining of insulation resistance of the charge-
mode models probe/cable assembly. Clean connectors
with suitable solvent and dry.
Contact factory for assistance should any problems
arise.
®ICP is a registered trademark of PCB Piezotronics

Drawing number: 21089
Revision: A
ECO: 52570
122 SERIES
HELIUM BLEED PRESSURE SENSOR