PCB Piezotronics 117B31 User manual

Model 117B31
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.