Dynamic Distributors 122A21 User Manual

Model 122A21

Helium Bleed, ICP® Dynamic Pressure Sensor

Installation and Operating Manual

For assistance with the operation of this product , contact the Pressure

Division of PCB Piezotronics, Inc.

Division toll-free 888-684-0015

24-hour SensorLineSM 716-684-0001

Fax [phone]

E-mail [e-mail]

Warranty, Service, Repair, and

Return Policies and Instructions

The informati on contained in this document supersedes all similar i nformation th at
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

Materials Authorization (RMA)
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
materials.

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 i s 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.

Warranty – All equipment and repair
services provided by PCB Piezotronics,
Inc. are covered by a limited warranty
against defective material and
workmanship for a period of one year
from date of original purchase. Contact

DOCUMENT NUMBER: 21354
DOCUMENT REVISION: B
ECN: 17900

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.

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 www.pcb.com.
Customers within the United States may
contact their local sales representative or
a factory customer service
representative. A complete list of sales
representatives can be found at
www.pcb.com. Toll-free telephone
numbers for a factory customer service
representative, in the division
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:

PCB Piezotronics, I nc.
3425 Walden Ave.
Depew, NY 14043 USA
Toll-free: [phone]
24-hour SensorLine

SM

: [phone]
Website: www.pcb.com
E-mail: [e-mail]

OPERATION MANUAL FOR

MODELS 122A, 122A21, 122A22, and 122A24

HELIUM BLEED PRESSURE SENSOR

1.0 INTRODUCTION

The series of sensors described in this guide is
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 model 122A contains a one pC/psi pressure
probe (sensor) and is designed to be used with
electrostatic charge amplifiers such as the PCB
Model 462A.

The Models 122A21, A22, and A24 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 122A 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 high­frequency response.

Series 122A: 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 Models 122A21, A22, and A23 Sensors use low
output-impedance probes (ICP) and will not require
the insulation resistance cautions described for Model
122A.

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.

1

®

Drawing number: 21089
Revision: NR