PCB Piezotronics IMI SENSORS M621B41 User manual

Model M621B41
High Frequency ICP® Accelerometer
Installation and Operating Manual
For assistance with the operation of this product,
contact PCB Piezotronics, Inc.
Toll-free: 800-959-4464
24-hour SensorLine: 716-684-0001
Fax: [phone]
E-mail: [email protected]
Web: www.imi-sensors.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.

MANUAL NUMBER: 18405
MANUAL REVISION: A
ECN NUMBER: 49766
Operating Guide with Enclosed Warranty Information
3424 Walden Avenue, Depew, New York 14043-2495
Phone [phone]
Fax [phone]
Toll Free Line 1-800-959-4IMI
Piezoelectric ICP® Accelerometers Operating Guide

General
OPERATING GUIDE
for use with
PIEZOELECTRIC ICP® ACCELEROMETERS
SPECIFICATION SHEET, INSTALLATION DRAWING AND CALIBRATION INFORMATION ENCLOSED
IMI ASSUMES NO RESPONSIBILITY FOR DAMAGE CAUSED TO THIS PRODUCT AS A RESULT OF
PROCEDURES THAT ARE INCONSISTENT WITH THIS OPERATING GUIDE
1.0 INTRODUCTION
Congratulations on the purchase of a quality ICP®
industrial sensor. In order to ensure the highest level of
performance for this product, it is imperative that you
properly familiarize yourself with the correct mounting
and installation techniques before attempting to
operate this device. If, after reading this manual, you
have any additional questions concerning this sensor or
its application, feel free to call an Application Engineer
at 716-684-0003 or 800-959-4464.
Proper sensor selection requires special attention to
three main areas: sensor design, dynamic
expectations, and application environment.
Sensor design encompasses the actual sensing
element, the physical material, and component
selection for the sensor. Preferred industrial
accelerometers employ a shear sensing element
with either a quartz or ceramic crystal.
Quartz sensing elements are typically used when
long-term stability and minimum output shifts due
to temperature changes are desired. Ceramic
sensing elements provide excellent resolution and
durability in noisy environments, and can be
designed to supply low-frequency and high-
frequency measurements. Shear-design sensors are
preferred because of their inherent insensitivity to
adverse environmental influences, such as case or
base strain and thermal transients. Internal case
isolation and shielding is important in avoiding
erroneous signals resulting from ground loops
and pick-up of electromagnetic and radio
frequency interference. Other critical material
selection criteria include non-magnetic stainless
steel housing, hermetic sealing, and industrial
military connectors. See Figure 1.
Dynamic expectations are application-specific and
referto the frequency range of measurement and the
anticipated amplitudes of vibration. After careful
review of the machinery to be monitored, minimum
and maximum measurement frequency ranges may
be established. The minimum measurement
frequency is normally related to any sub-harmonics of
running speed or any lower frequencies where
vibration data is to be collected. The maximum
measurement frequency of interest is determined by
the maximum number of harmonics of an event like
running speed, bearing frequencies, or gear mesh.
This measurement frequency range should be well
within the specified frequency range ofthe sensor.
Amplitude range refers to the anticipated levels of
vibration to be measured. These values are related
to the alarm levels set for the machine. By carefully
evaluating the idiosyncrasies of the machinery, the
predictive maintenance engineer can estimate the
minimum expected vibration levels and ensure that
the electrical noise floor of the accelerometer is less
than those levels.

The environment of the application is a critical
consideration during program implementation. The
sensor chosen must be capable of surviving the wide
range of conditions to which it is subjected;
therefore, take time to evaluate potential
conditions, such as high temperatures and chemical
contaminants. The specified temperature range of
the sensor must conform to the fluctuations of the
environmental temperature. If harsh industrial
chemicals are present, the sensor requires hermetic
sealing and construction that resists corrosion.
Finally, specific location of the sensor within the
environment must be sensible, as both cable and
sensor may be damaged by imprudent installation in
heavily traveled, physically punishing areas.
2.0 ICP® ACCELEROMETERS
Enclosed in the back of this guide is a Specification
Sheet, which lists the complete performance
characteristics of the particular sensor.
All ICP® sensors require a constant current power
source for proper operation. A typical sensing
system includes an ICP® sensor, ordinary two
conductor cable and a basic constant current power
supply (as shown in Figure 2).
The signal conditioner consists of a well-regulated 18
to 30 VDC source (battery or line-powered), a
current-regulating diode (or equivalent constant
current circuit), and a capacitor for decoupling
(removing the bias voltage) the signal.
The current-regulating device is used in place of a
resistor for several reasons. The very high dynamic
resistance of the diode yields a source follower gain
which is extremely close to unity and independent of
input voltage. Also, the diode can be changed to supply
higher currents for driving long cable lengths. Constant
current diodes, as shown in Figure 3, should be used in
ICP® signal conditioners. (The correct orientation of the
diode within the circuit is critical for proper operation.)
Except for special models, standard ICP® sensors require
a minimum of 2 mA for proper operation.
The typical limits for this type of diode are to a 4 mA
maximum rating; however, several diodes can be placed in
parallel for higher current levels. All line-powered signal
conditioners should use higher capacity (up to 20 mA)
constant current circuits in place of the diodes, particularly
when driving long signalcables (see Section 5).
Decoupling of the data signal occurs at the output stage
of the signal conditioner. A 10 to 30 µF capacitor coupled
with a resistor shifts the signal level to essentially
eliminate the sensor bias voltage. The result is a drift-free
AC mode of operation.
3.0 OPTIONAL FEATURES
In addition to standard features, a variety of options
are also available. When listed before the model
number, the following prefix letters indicate that the
sensor is manufactured or supplied with optional
features:
CS - Canadian Standards Association Approved
Sensor
D - Dummy, non-working sensor for display purposes
EX - Cenelec Approved Sensor
FM - Factory Mutual Approval Sensor
HT - High temperature accelerometer (325 ˚F)
LB - Low Bias electronics
LC - Limited Calibration (one point calibration)
LP - Low Pass filter
M - Metric mounting hardware and cable length
U - Usable demonstration sensor (does not meet one
of more minor specifications)
VO - Velocity Output Sensors

MS –Mine Safety Approved Sensors
TO –Temperature Output Sensor
Note: Not all sensors are available with the optional
prefixes. Contact the factory to discuss special
features that may be needed.
4.0 INSTALLATION OVERVIEW
When choosing a mounting method, consider closely both
the advantages and disadvantages of each technique.
Characteristics like location, ruggedness, amplitude range,
accessibility, temperature, and portability are extremely
critical. However, the most important and often
overlooked consideration is the effect the mounting
technique has on the high-frequency operating range of
the accelerometer.
Shown in Figure 4 are six possible mounting techniques
and their effects on the performance of a typical
piezoelectric accelerometer. (Note: Not all of the
mounting methods may apply to your particular sensor.)
The mounting configurations and corresponding graph
demonstrate how the high-frequency response of the
accelerometer may be compromised as mass is added to
the system and/or the mounting stiffness is reduced.
Note: The low-frequency response is unaffected by the
mounting technique. This roll-off behavior is typically fixed
by the sensor’s built-in electronics. However, when
operating AC-coupled signal conditioners with readout
devices having an input impedance of less than one
megaohm, the low frequency range may be affected.
4.1 STANDARD STUD MOUNT
This mounting technique requires smooth, flat
contact surfaces for proper operation and is
recommended for permanent and/or secure
installations. Stud mounting is also recommended
when testing at high frequencies.
Note: Do NOT attempt mounting on curved, rough,
or uneven surfaces, as the potential for misalignment
and limited contact surface may significantly reduce
the sensor’s upper operating frequency range.
STEP 1: First, prepare a smooth, flat mounting
surface and then drill and tap a mounting hole in the
center of this area as shown in Figure 5.
A precision-machined mounting surface with a
minimum finish of 63 µin (0.0016 mm) is
recommended. (If it is not possible to properly prepare
the machine surface, consider using an adhesive
mounting pad as a possible alternative.) Inspect the
area, checking that there are no burrs or other foreign
particles interfering with the contact surface.
STEP 2: Wipe clean the mounting surface and spread
on a light film of grease, oil, or similar coupling fluid
prior to installation. See Figure 6.
Adding a coupling fluid improves vibration
transmissibility by filling small voids in the mounting
surface and increasing the mounting stiffness. For

semi-permanent mounting, substitute epoxy or another
type of adhesive.
STEP 3: Hand-tighten the sensor/mounting stud to the
machine, then secure the sensor with a torque wrench to
the mounting surface by applying the recommended
mounting torque. (See enclosed specification data sheet
for proper mounting torque.)
It is important to use a torque wrench during this step.
Under-torqueing the sensor may not adequately couple
the device; over-torqueing may result in stud failure and
possibly permanent damage.
4.2 ADHESIVE MOUNT
Adhesive mounting is often used for temporary
installation or when the machine surface cannot be
adequately prepared for stud mounting. Adhesives like
hot glue or wax work well for temporary mounts; two-part
epoxies and quick-bonding gels provide a more
permanent mount.
Note: Adhesively-mounted sensors often exhibit a
reduction in high-frequency range. Generally, smooth
surfaces and stiff adhesives provide the best frequency
response. Contact the factory for recommended epoxies.
METHOD 1 –Adhesive mounting base
This method involves attaching a base to the machine
surface, then securing the sensor to the base. This allows
for easy removal of the accelerometer.
STEP 1: Prepare a smooth, flat mounting surface. A
minimum surface finish of 63 µin (0.0016 mm) generally
works best.
STEP 2: Stud-mount the sensor to the appropriate
adhesive mounting base according to the guidelines set
forth in STEPS 2 and 3 of the Stud Mount Procedure.
STEP 3: Place a small portion of adhesive on the underside
of the mounting base. Firmly press down on the assembly
to displace any extra adhesive remaining under the base.
See Figure 7.
METHOD 2 –Direct Adhesive Mount
For restrictions of space or for convenience, most sensors
(with the exception of integral stud models) can be
adhesive-mounted directly to the machine surface.
STEP 1: Prepare a smooth, flat mounting surface. A
minimum surface finish of 63 µin (0.0016 mm) generally
works best.
STEP 2: Place a small portion of adhesive on the
underside of the sensor. Firmly press down on the
top of the assembly to displace any adhesive. Be
aware that excessive amounts of adhesive can make
sensor removal difficult. See Figure 8.
4.3 MAGNETIC MOUNT
Magnetic mounting provides a convenient means for
making portable measurements and is commonly used
for machinery monitoring and other portable or trending
applications.
Note: The correct magnet choice and an adequately
prepared mounting surface are critical for obtaining
reliable measurements, especially at high frequencies.
Poor installations can cause as much as a 50% drop in the
sensor frequency range.
Not every magnet is suitable for all applications. For
example, rare earth magnets are commonly used
because of their high strength. Flat magnets work well
on smooth, flat surfaces, while dual-rail magnets are
required for curved surfaces. In the case of non-magnetic
or rough surfaces, it is recommended that the user first
weld, epoxy, or otherwise adhere a steel mounting pad
to the test surface. This provides a smooth and
repeatable location for mounting.
STEP 1: After choosing the correct magnet type,
inspect the unit, verifying that the mounting surfaces
are flat and smooth. See Figure 9.