PCB Piezotronics 090B274 User manual

Model 090B274
CALIBRATION ADAPTOR
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: [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: 21105
Revision: NR
OPERATION MANUAL FOR
BALLISTICS PRESSURE SENSOR CALIBRATION ADAPTOR
FOR AMMUNITION TESTING
Model 090B
1
1.0 INTRODUCTION
The Series 090B Calibration Adaptors are designed
to facilitate calibration of the Model 117B Conformal
Pressure.
An actual empty cartridge case is pressurized with
precisely known hydraulic pressure and the
corresponding output of the sensor is read at each
pressure point to full scale.
2.0 DESCRIPTION
Refer to Drawing No. 090-2 -90 included as part of
this manual.
The Model 090B Adaptor Assembly consists of a
pressure chamber (Item 1) a pressure chamber
adaptor (Item 2), a cartridge case retainer (Item 3),
and a retaining nut (Item 4).
The pressure chamber adaptor (Item 2) contains an
O-ring to affect a pressure seal when the adaptor is
pushed into the cartridge case mouth. The opposite
end of this item is designed to mount directly into a
standard mounting port for the PCB Models 118A,
108A, 119A and 109A pressure sensors. This feature
precludes the need for high pressure fitting, tubing,
etc. thereby, keeping the total pressurized volume to a
minimum.
3.0 INSTALLING THE SENSOR
The sensor is installed in the empty pressure chamber
(Item 1) so that the flushness of the curved diaphragm
with the I.D. of the test chamber can be observed.
Before installing the sensor into the Model 090B
Adaptor, read the installation instructions supplied
with the specific sensor for which this adaptor is
designed.
Follow these instructions carefully paying particular
attention to the depth adjustment. The rotational
alignment is automatically controlled by the
alignment device incorporated in all 117B Conformal
Sensors.
4.0 INSTALLATION OF THE
CARTRIDGE CASE
(Refer to Installation Dwg. No. 090-2 -90)
It is important that cartridge case selected for
calibration be identical in all respects including
material, to the lot of ammunition undergoing test. It
is advisable that the test unit be selected from the
same lot as the ammunition under test for greatest
accuracy of test results.
For small arms cartridge cases, it is necessary to use a
case with the primer in place, but fired.
Note: Do not use a cartridge case with an unfired
primer or a case which has drilled holes.
If a sample cartridge is a loaded round, remove bullet
and powder, then fire the primer.
On certain calibers an O-ring is provided in the
cartridge case retainer (Item 3) to effect a pressure
seal at the boltface end of the case.
Inspect the boltface surface for irregularities or
imperfections in the area of this O-ring, which could
preclude a pressure seal.
Note: For shotshell installation, consult enclosed
drawing for necessary modification to the empty
shotshell case. The case must be cut to a specified
overall length to fit properly into the calibration
fixture due to inconsistencies in the designs of the
various makes of ammunition.
4.1 STEP-BY-STEP INSTALLATION
PROCEDURE
1. Remove Items 2, 3, and 4 from chamber body
(Item 1).
Note: For metallic cartridges, it is extremely
important that the mouth of the cartridge case be
chamfered to allow easy entry of the O-ring on
the pressure chamber adaptor. This operation is
easily performed with a hand held 90°
countersink or a sharp de-burring tool. If this is
not done, O-ring life will be drastically
shortened.

Drawing Number: 21105
Revision: NR
OPERATION MANUAL FOR
BALLISTICS PRESSURE SENSOR CALIBRATION ADAPTOR
FOR AMMUNITION TESTING
Model 090B
2
Insert the empty cartridge case into the chamber
body (Item 1) as shown. Inspect the cartridge
case retainer (Item 3) for an O-ring groove,
which will be found on certain calibrators. If an
O-ring groove is found, an O-ring must be used
with this item. Lubricate O-ring with silicone
grease or equivalent and install on to the
cartridge case retainer (Item 3).
Install the cartridge case retainer (Item 3) and
tighten until its shoulder bottoms snugly against
the chamber body.
2. Slide the retaining nut (Item 4) over chamber
adaptor (Item 2), with the threaded portion first,
facing the o-ring groove. See drawing 090-2 -
90. Install this chamber adaptor/retaining nut
assembly into the test port of a high pressure
hydraulic source (dead weight tester or pressure
pump with reference pressure gage) using
065A06 seal ring. Using the hex flats on the
chamber adaptor, tighten the chamber
adaptor/retaining nut assembly to approx. 20 ft.
lbs. of torque.
Note: Do not over torque as chamber or seal
could be damaged.
3. Lubricate the O-ring on the chamber adaptor
(Item 2) with silicone grease or hydraulic oil.
Insert the open end of the chamber body (Item 1)
onto the chamber adaptor (Item 2). Insert fully
until end of chamber body meets large diameter
seat on the chamber adaptor.
Thread the retaining nut (Item 4) over the
chamber adaptor, snugly. It will not be necessary
to use large amounts of torque on this nut to
affect a pressure seal.
4. Connect 117B to an electrostatic charge amplifier
(such as PCB Model 462A or 462B52) on "long
time constant".
Zero the system electrically by moving front
panel toggle to "gnd" position momentarily.
5.0 COLLECTING THE DATA
It is important to proceed carefully while performing
the calibration to avoid procedures which could lend
inherent error to the results.
The recommended procedure is as follows:
1. Allow at least 15 minutes for test equipment to
warm-up and stabilize after connecting sensor to
charge amplifier and charge amplifier to digital
volt meter.
2. Since the end result of the sensor calibration is a
determination of sensor slope (in units of
picocoulombs/psi) it will be convenient to range
the charge amplifier so that the output charge
can be read directly in picocoulombs.
To facilitate this, choose the 1000 units/volt
range for the miniature versions of the Model
117B (for pressure to 40,000 psi) and 10,000
units/volt for the standard versions (for pressure
to 80,000 psi).
Set the dial gain pot to 10.00 and verify, by
calibration that the transfer function of the
Charge Amplifier is precisely 1000 pC/volt
and/or 10,000 pC/volt.
3. Set the charge amplifier time constant switch to
"long", switch to "gnd" position and zero the
charge amplifier. Switch to operate and observe
the zero for 15 seconds. No drift should be
observed.
If excessive drift is observed, check for faulty
cable or contamination on connector of sensor.
4. Apply pressure, increasing to 10,000 psi. Set
pressure precisely, using reference gage and
allow pressure to remain at this level for
approximately 5 seconds. Readjust pressure if
necessary and record voltage reading.

Drawing Number: 21105
Revision: NR
OPERATION MANUAL FOR
BALLISTICS PRESSURE SENSOR CALIBRATION ADAPTOR
FOR AMMUNITION TESTING
Model 090B
3
5. Without dropping pressure, immediately
proceed to next pressure level, set pressure and
record reading.
NOTE: For sensors with full scale range of
40,000 psi or less, calibration increments of
5,000 psi are used. For sensors with full scale
range above 40,000 psi, increments of 10,000
psi are used.
Proceed in this manner to full scale.
6. It is important to note that the test pressure must
always be approached from below, i.e. by
increasing pressure, never decreasing.
Use only unfired cases since the hardness of
fired cases may have been altered.
Do not cycle case before calibrating. Take one
set of readings on each case, then discard the
case.
If the test pressure at any point is exceeded by
more than 5%, discard the case and the data and
start over with another case.
8. Repeat procedure for each case to be
calibrated.
6.0 ORGANIZING THE DATA
Since the family of values of output charge at each
calibration point follows a random distribution about
a mean value, the standard deviation at each point is a
valid indication as to the preciseness of the
calibration at that point.
A convenient format for tabulating this data and
calculating the standard deviation is shown in figures
1 and 2.
7.0 UTILIZING THE DATA
See "An Improved Technique for Utilization of
Conformal Ballistics Sensor Calibration Data",
attached.
8.0 OPERATION
Apply pressure slowly, starting with the lowest
pressure working toward the highest, set the pressure
to specific values precisely and read corresponding
voltage output at each point. Do not dump pressure
at each point.
Due to the fact that a certain amount of pressure is
necessary to expand the cartridge case, a severe non-
linearity will be noticed at the low end of the
calibration curve.
A special technique has been developed to handle this
problem. Refer to the enclosed paper "An Improved
Technique for Utilization of Conformal Sensor
Calibration Data" for instructions in collecting and
using the conformal calibration data.
Also, read the operating guide supplied with the
sensor for further pertinent information regarding use
of the 090B Calibrator.
9.0 PRESSURE LIMITS
It is very important that maximum pressures are not
exceeded for the safety of operating personnel.
For pistol calibrators, and 22 rimfire, the maximum
pressure is 40,000 psi. For center fire rifle cartridges,
the maximum hydraulic pressure is 60,000 psi.
Do not exceed these pressures. The units were tested
at the factory only to the pressures stated here.
Exceeding these pressures may endanger personnel
operating this equipment.

Drawing Number: 21105
Revision: NR
OPERATION MANUAL FOR
BALLISTICS PRESSURE SENSOR CALIBRATION ADAPTOR
FOR AMMUNITION TESTING
Model 090B
4
Figure 1

Drawing Number: 21105
Revision: NR
OPERATION MANUAL FOR
BALLISTICS PRESSURE SENSOR CALIBRATION ADAPTOR
FOR AMMUNITION TESTING
Model 090B
5
Figure 2

Model 117B229
CONFORMAL BALLISTICS 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: [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: 21210
Revision: NR
AN IMPROVED TECHNIQUE FOR
UTILIZATION OF CONFORMAL BALLISTICS
SENSOR CALIBRATION DATA
1
The PCB Series 117B Conformal Ballistics Sensor
(patented) measures chamber pressure in a novel
manner.
The sensitive surface of the sensor, when properly
installed in the gun chamber, conforms or blends in
precisely with the inside surface of the chamber actually
forming a portion of the wall adjacent to the cartridge
case.
When the round is fired, the pressure builds up rapidly
inside the case, obturating the case outward against the
chamber. The force, transmitted through the thin
cartridge case wall stresses the sensor crystals producing
an output charge analogous to chamber pressure.
An exclusive calibration technique has been developed
in conjunction with the conformal sensor, consisting of a
simulated gun chamber which positions the sensor at the
same location as in the test barrel and provides for
hydraulic pressurizations of an actual cartridge case.
Using this system and a reference standard pressure
source, a point by point calibration is performed on
samples of the actual lot of ammunition under test to
take into account transmissibility characteristics of the
cartridge case for each lot of ammunition.
Because a certain amount of pressure is required to fully
obturate the cartridge case in the test chamber, a rather
severe non-linearity is exhibited over the first several
thousand psi of input pressure, i.e. until the cartridge
case is pressed firmly against the inside chamber walls.
Figure 1 illustrates a typical calibration result with .22
caliber rimfire ammunition.
Figure 1: Typical calibration graph
Conformal sensor with .22 caliber rimfire.
As shown in figure 1, the best straight line that can be
drawn through the majority of the data points in the
linear portion of the curve, does not pass through the
origin.
Because of this, the widely accepted zero based best
straight line method of linearity determination cannot be
applied to the conformal sensor. Also, the actual
sensitivity of this sensor may only be specified at one
input pressure level since the sensitivity is not a
constant, but varies with input pressure level.
This paper outlines a simple alternative approach to
utilization of conformal sensor data.
The most universally accepted method of defining
conventional sensor nonlinearity is the full scale error
band method used in conjunction with the zero based
best straight line.

Drawing Number: 21210
Revision: NR
AN IMPROVED TECHNIQUE FOR
UTILIZATION OF CONFORMAL BALLISTICS
SENSOR CALIBRATION DATA
2
Figure 2: Zero based best straight
line method of linearity determination.
To utilize the zero based best straight line method, the
corresponding value of the sensor output is plotted for
each value of input measurand up to full scale as shown
in Figure 2.
A straight line, intercepting the origin as shown, is fitted
to the data points by equalizing the error between the
points below the line and the points above the line.
Error bands, as delineated by the instrument
specification are constructed as shown in figure 2.
Typically, plus and minus one or two percent of full
scale is specified for quartz sensors.
An acceptable instrument is then defined as one whose
data points all fall within this error band.
The "sensitivity" of an instrument so calibrated is simply
the full scale output (charge or voltage) divided by full
scale input pressure, where F.S. output is determined by
the straight line as defined above.
input.S.F output.S.F
ySensitivit (Eq. 1)
The units for sensitivity are commonly pC/psi or
mV/psi.
Note that in this case, the sensitivity is identical to the
slope of the line, since the line does intersect the origin
by previous definition.
The general equation for a straight line in terms of the
dependent variable is:
y = mx + b (Eq. 2)
Figure 3
b in equation 2 is the y axis intercept.
m is the slope of the line defined as:
12
12 xx yy
tanθm

 (Eq. 3)
Equation 2, expressed in terms of the independent
variable x is:

Drawing Number: 21210
Revision: NR
AN IMPROVED TECHNIQUE FOR
UTILIZATION OF CONFORMAL BALLISTICS
SENSOR CALIBRATION DATA
3
C
m
y
x (Eq. 4)
Where C is the X-axis intercept.
Equation 4 is directly applicable to the conformal sensor
even through the X variable (psi) becomes the
dependent variable when using the sensor output to
determine pressure.
Consider again the calibration graph of a typical
conformal sensor, shown in figure 4.
To calibrate a conformal sensor, the input pressure is
increased in discrete steps from 0 psi to full scale with
the corresponding output recorded at each step. The
information must be taken only once and only with
increasing pressure. A repeat run on the same cartridge
case will not yield the same values as the initial run due
to work hardening of the cartridge case metal.
Figure 4
At the lower pressures, the sensor has very little output
because there is a certain amount of clearance between
the cartridge case and the chamber wall. Obturation of
the cartridge occurs in this region.
However, when obturation is complete, the sensor
output is then linear with pressure from this point up to
maximum rated pressure.
In the past, a common procedure has been to calibrate
the conformal at the expected nominal pressure, deriving
a sensitivity at this point, e.g. point Po, Qo in figure 4.
The sensitivity determined by dividing output Qo by
corresponding pressure input Po, would then yield the
exact result if the input pressure was always exactly Po.
However, should the input pressure change to Pa, it is
clear that the reading would be in error, as shown in Fig.
4, since the actual sensitivity of the instrument is not the
same at Po, as it is at Pa.
A solution to this problem lies in utilization of equation
4.
C
m
y
x (Eq. 4)
Expressed in terms of sensor transfer parameters, input
pressure and output charge
intercept
(pC/psi)slope (pC)chargeindicated
(psi)pressureIndicated


(Eq. 5)
Where the slope of the line is defined as:
psi
pC
PP QQ
Slope
12
12


(Eq. 6)
and the intercept is the pressure axis intercept.

Drawing Number: 21210
Revision: NR
AN IMPROVED TECHNIQUE FOR
UTILIZATION OF CONFORMAL BALLISTICS
SENSOR CALIBRATION DATA
4
The straight line is the best line that can be constructed
through the linear portion of the curve as shown in
Figure 4 and the pressure intercept (or offset) is the
point at which this line crosses the pressure axis, in psi.
Instead of establishing the sensitivity parameter (which
has been shown to have little meaning for this sensor)
the user now determines the slope as defined in Eq. 6
and the accompanying pressure offset by constructing
the best straight line as described previously.
Pressures P1 and P2 are arbitrarily established at some
point well above and well below the expected nominal
pressure of the test.
The corresponding outputs at these pressures should be
an average of at least 20 cartridges taken from the same
lot of ammunition as is under test.
The main difference between utilization of the data with
this method is that now a constant (pressure offset) must
be added to each reading. However, this can be easily
handled by most data reduction methods in use today.
Example:
In actual practice, this is how a conformal sensor/charge
amplifier system could be utilized:
Assume that averaging the data from 20 consecutive
calibration runs performed on a conformal sensor
yielded a slope of .04 pC/psi and an intercept of 7,500
psi, determined by constructing the best fitting straight
line as described previously.
Assume also that average expected peak pressure is
25,000 psi.
Approximate full scale charge output is:
pC1000pC/psi.04psi25,000


Set range of charge amplifier output to 1000 pC/volt (or
other desired range).
Read peak output voltage of .800 volts during test.
Peak indicated charge is then:
1000 pC/volt x .80 volts = 800 pC
Indicated peak pressure is:
offset
slope
chargepeak
(pk)Pressure 
psi7,500
pC/psi.04 pC800
P
P = 20,000 psi + 7500 = 27,500 Psi
As previously stated, this method will yield accurate
results anywhere within the linear portion of the sensor
calibration curve without inherent errors due to
variability of sensitivity with pressure level.
Accuracy should be close to that expected for standard
piezoelectric sensors within the limitation of
transmissibility variations in the cartridge cases.
Simplified standardization techniques for Conformal
Sensor
The technique described by the previous example
outlines one basic method of output signal utilization.
This method in actual practice may be cumbersome for
repeated testing because of the conversions that must be
made from measured charge output to indicated peak
pressure.
Other system scaling methods exist which further
simplify signal utilization.

Drawing Number: 21210
Revision: NR
AN IMPROVED TECHNIQUE FOR
UTILIZATION OF CONFORMAL BALLISTICS
SENSOR CALIBRATION DATA
5
Dial Gain Standardization
Many charge amplifiers feature a calibrated gain pot for
dialing in sensor sensitivity for the purpose of setting
system sensitivity to standardized unit of output voltage
(PCB Model 462A).
To utilize such amplifiers, dial in the actual value of
slope as determined by the calibration graph for the
particular ammunition lot.
Using the slope value effectively displaces the
calibration curve to pass through the origin (0) of the
calibration graph.
See Figure 5.
Figure 5
The indicated peak pressure P2 from the conformal,
which through scale factoring can be read to read
directly in psi (on a digital peak meter for example) is
simply added to the offset pressure to arrive at true peak
pressure, P1 + P2
This process can be further refined to, include a variable
voltage source as a bias in series with the output of the
charge amplifier. This voltage bias can be set to
simulate the offset pressure, and then the true peak
pressure can be read directly. (See figure 6 on the next
page)
Example:
Assume a 20 round calibration lot and attendant graph
yield a slope of .250 pC/psi and an offset of 5,000 psi.
Proceed as follows:
Dial the slope (.250) into the dial gain pot and select a
convenient full scale range over which to operate.
For example, for an expected full scale range of 40,000
psi, select 10,000 units/volt.
Now the indicated peak pressure can be read directly
from a digital peak holding meter such as the PCB
Model 451B.
If the offset supply is not used, simply add the offset
pressure (5,000 psi) to the indicated pressure to arrive at
true peak pressure.
If an offset supply is used as in figure 6 simply dial in
the offset voltage equivalent to offset pressure. Now the
offset will be automatically added and the true peak
pressure can be read directly from the peak meter.