Cirrus Research revo CV31A User manual

CV:31A Vibration Meter User Manual
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CV:31A Vibration Meter
User Manual
This manual, the software to which it relates, the
program code and drawings are all:
© Copyright Cirrus Research plc 1989-2022

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The content of this manual, any illustrations, technical information and descriptions within this document
were correct at the time of going to print. Cirrus Research plc reserves the right to make any changes
necessary, without notice, in line with the policy of continuing product development and improvement.
No part of this publication may be duplicated, reprinted, stored in a data processing system or transmitted
by electronic, mechanical, photographic or other means, or recorded, translated, edited, abridged or
expanded without the prior written consent of Cirrus Research plc.
No liability is accepted for any inaccuracies or omissions in this manual, although due care has been taken
to ensure that is it complete and accurate as possible.
Accessories supplied by Cirrus Research plc have been designed for use with the instrumentation
manufactured by Cirrus Research plc. No responsibility is accepted for damage caused by the use of any
other parts or accessories.
In order to take account of a policy of continual development, Cirrus Research plc reserves the right to
change any of the information contained in this publication without prior notice.
Produced by Cirrus Research plc, Acoustic House, Bridlington Road, Hunmanby, North Yorkshire, YO14
0PH, United Kingdom.
© Copyright Cirrus Research plc 2022
Reference Number 07/17/CV31A/04

CV:31A Vibration Meter User Manual
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Introduction ................................................................................................................. 5
Instrument Overview ................................................................................................... 5
Getting started with the CV:31A ................................................................................... 6
Switching on and Connecting the Sensor ..........................................................................6
Hand-Arm Vibration Measurement with the CV:31A ..................................................... 7
Measuring Points for Hand-Arm Vibration .........................................................................7
CV:31A Settings for Hand-Arm Vibration measurements ....................................................8
Whole-Body Measurement with the CV:31A ............................................................... 10
Measuring Points for Whole-Body Vibration .....................................................................10
CV:31A Settings for Whole-Body vibration measurements ................................................11
Whole-Body Measurement with RMS Values ...............................................................................11
Whole-Body Vibration Measurement with VDV Values ..................................................................13
Seat Effective Amplitude Transmissibility (SEAT).........................................................................14
General Vibration Measurement ................................................................................. 15
Data Logger................................................................................................................ 18
Frequency Analysis..................................................................................................... 19
Instrument Settings ................................................................................................... 19
Sensor Calibration .......................................................................................................19
Time & Date ...............................................................................................................20
Shut-off Timer ............................................................................................................20
Battery Type...............................................................................................................20
Battery Replacement ...................................................................................................21
Display Brightness .......................................................................................................22
Language ...................................................................................................................22
Default Settings ..........................................................................................................22
Data Memory .............................................................................................................. 23
Measurement data memory ..........................................................................................23
Data Logger Memory ...................................................................................................23
FFT Data Memory ........................................................................................................24
Keypad Lock ...............................................................................................................24
Instrument Reset ........................................................................................................24
Data Transfer to a PC ................................................................................................. 25
Connection to a PC ......................................................................................................25
Opening the Excel File CV31.xlsm..................................................................................25
Data import to the Excel worksheet ...............................................................................26
Calculation of Vibration Exposure A(8) and VDV(8) ..........................................................27
Data Logger Import .....................................................................................................28
FFT Import .................................................................................................................30
Appendix 1 Fundamentals of Human Vibration Measurement ..................................... 31
Introduction................................................................................................................31
EU Occupational Health Directive 2002/44/EC .................................................................31
Exposure Limit Values .............................................................................................................32
Appendix 2 Weighting Filters...................................................................................... 36
Hand-arm weighting filter Wh .......................................................................................36
Whole-body weighting filter Wd.....................................................................................36
Whole-body weighting filter Wk.....................................................................................37
Whole-body weighting filter Wb for passenger trains........................................................37
Whole-body weighting filter Wc for the backrest of seats ..................................................38
Whole-body weighting filter Wj for the head of recumbent persons ....................................38
Whole-body weighting filter Wm for persons in buildings ..................................................39
Appendix 3 Specifications........................................................................................... 40
Appendix 4 CE Declaration of Conformity ................................................................... 41

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Warranty Information. ............................................................................................... 42
Cirrus Research Offices .............................................................................................. 43

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Introduction
The CV:31A has been developed for the measurement and analysis of human vibration.
It can also be used for a range of other applications including machine condition
monitoring, building vibration measurement and quality control.
In combination with a tri-axial accelerometer, hand-arm and whole-body vibrations can
be measured in compliance with ISO 5349, ISO 2631 and the EU Directive 2002/44/EC.
A fourth measuring channel can be used, for example, for SEAT measurements (seat
effective acceleration transmissibility). The CV:31A meets the requirements for human
vibration meters in compliance with ISO 8041.
Note that the Excel Macro version 2.1 or later is required to download the information
stored by the data logger.
Instrument Overview

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Getting started with the CV:31A
Switching on and Connecting the Sensor
Switch on the CV:31A by pressing the ON/OFF key.
If the sensor has not yet been connected, plug the sensor cable
into the right connector.
The CV:31A will start TEDS1detection if the sensor is
compatible with IEEE 1451.4 Template 25.
It will automatically read the three sensitivities of the X/Y/Z
directions. Confirm the sensitivities by pressing OK.
The sensors KD:103 and KD:903 accelerometers available for the the CV:31A feature
TEDS (Transducer Electronic Data Sheet) which allow the instrument to read calibration
information from the sensor.
Should a connected sensor not have TEDS, the CV:31A will open a menu for entering
the sensitivities manually.
The sensitivities entered remain stored as long as the sensor is connected, even if the
batteries are removed.
Sensor detection will only take place if the display showed “SENSOR!” before a new
sensor was connected.
The warning “SENSOR!” may also indicate a defective sensor or a broken sensor cable.
Sensor condition is detected by means of the bias voltage at the sensor output:
< 0.7 V: short circuit
0,7 –14 V: normal
>14 V: open, e.g. broken cable
Please note that the settling time after connecting a sensor is about 1 minute.
The CV:31A is suitable for connecting any low power IEPE accelerometers which can be
operated with a 1 mA supply current. The internal compliance voltage of the current
sources is 18 VDC.

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Hand-Arm Vibration Measurement with the CV:31A
This section will give you basic instructions for the measurement and evaluation of
hand-arm vibrations based on the standard ISO 5349 and the guideline VDI 2057, Part
2.
Please consult the original documents for detailed explanations.
Measuring Points for Hand-Arm Vibration
The sensors should be attached as close as possible to the gripping points of the hand,
however, they must not interfere with the work process.
Measurements should be performed with the same hand pressure force as used under
normal operating conditions.
Since most machine tool handles do not provide surfaces for the adhesive or screw
attachment of sensors, Cirrus offers some mounting accessories for curved surfaces.
Figure 7: Handle adapter ML:311
Figure 8: Handle adapter ML:312
The adapter ML:311 is attached with a plastic cable strap. The ML:312 is pressed onto
the handle by the hand.
Close contact between the sensor and the machine is of great importance. Any motion
of the sensor would distort the measurement.

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Figure 9 shows the axis directions for attaching the sensor to the handle. For cylindric
handles the Y direction points in the direction of the handle axis. The Z axis is
approximately the extension of the third metacarpal bone.
Figure 9: Coordinate system of the hand (from ISO 5349-1)
CV:31A Settings for Hand-Arm Vibration measurements
For the evaluation of hand-arm vibration it is recommended
to measure both the interval RMS values of X/Y/Z and their
vector sum aW.
The vector sum of the RMS values is displayed on the screen
as aw(Vec).
This is also known as ahv as described in ISO 5349-1:2001.
The CV:31A measures these four values simultaneously. In
addition it shows the maximum running RMS (Maximum
Transient Vibration Value, MTVV) which may indicate the
presence of shock vibration.
The frequency weighting for hand-arm vibration is Wh.
Appendix 2 shows the filters of the CV:31A and the tolerance bands to ISO 5349.
Press the F3 key to open the main menu and select
Human vibration
Hand-Arm ISO 5349
Health
After returning to the measurement screen you can check the settings by pressing F1.
Measurements can begin when the sensor and the worker's hands have been placed on
the handle of the object carrying out the operation. To start the measurement press the
key ►(Reset). This will result in the following:
•the RMS values of X/Y/Z, the vector sum aWand MTVV reset to zero
•the measurement timer restarts

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Pressing Reset before a measurement is mandatory to establish defined start
conditions.
The RMS values of X/Y/Z and the vector sum are averaged over the entire measuring
time. That's why fluctuation becomes less the longer the measurement takes. After a
while short shock pulses have almost no influence on the displayed results.
Recommended measuring time for hand-arm vibration is at least 60 seconds. The
measuring timer in the upper right corner remains red until 60 seconds have elapsed.
“OVERLOAD” is indicated instead of the measuring values if the current magnitude is
too high. Even if the overload condition was of short duration the measured interval
RMS value may become invalid because of missing samples.
An overload event during the entire averaging time is indicated by “OVL!” in the upper
right corner after the date. This warning can be deleted by pressing the key ►(Reset).
After measurement you may save the results by pressing the
key ▼. Measurement should be continued or finished
immediately before pressing the key, otherwise the measuring
values will drop slowly.
You will be asked to enter two lines of ten capital letters or
numbers as a comment. Use the keys ◄▲▼► to select
characters and to change the input position.
Press F1 to change the input line. Measurement can be
finished before entering the comment because the results
have already been saved when pressing the key ▼.
Measurements can only be saved if a sensor is detected at X/Y/Z and if there is no
overload condition. In these cases the CV:31A will display “Sensor error” or “Overload
occurred” instead of saving in order to avoid invalid recordings.
If an overload occurred since the last reset (“OVL!” in upper right corner) the
instrument will show a warning “Overload occurred after last reset! Save anyway?”.
If you want to measure several partial exposures you may do further measurements
For the calculation of vibration exposure A(8) and to store results on a PC the Excel
macro file is provided. See page 25 for details of transferring measurement to a PC.
The fourth channel (A) of the CV:31A is not active when hand-arm vibration is
measured.

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Whole-Body Measurement with the CV:31A
This section will give you basic instructions for the measurement and evaluation of
whole-body vibrations based on the standard ISO 2631 and the guideline VDI 2057,
Part 1. Please consult the original documents for detailed explanations.
The described method is suitable for all vibrations acting on the human body. It is not
suited for vibration containing occasional shocks or for impacts such car crashes.
Vibrations transmitted via the hands are described separately in the previous section.
Measuring Points for Whole-Body Vibration
Whole-body vibration is usually measured with seat pad accelerometers. These are
triaxial piezoelectric sensors built into a flat rubber pad, which adapt themselves to the
interface between the vibration source and the test person (Figure 4).
The following measuring points are suitable:
•On the seat surface under a seated person
•On the back rest behind a seated person
•Under the feet of a seated person
•Under the feet of a standing person
•Under the pelvis of a recumbent person
•Under the head of a recumbent person
•
Figure 13 shows the coordinate systems for whole-body vibration to ISO 2631. As can
be seen from the drawing, the Z axis always points in the direction of the spinal
column.
The vibration sensor has to be placed accordingly. A special case is measurement at the
backrest (see notice below Table 2 on page 10).
Figure 13: Coordinate systems for whole-body vibration to ISO 2631

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Table 2 shows the weighting filters and factors to be used for different postures and
positions.
Whole-Body Health Evaluation
Posture
Position
Direction
Frequency weighting
Weighting factor (k)
sitting
seat surface
X / Y
Z
Wd
Wk
1.4
1
Whole-Body Comfort Evaluation
sitting
seat surface
X / Y
Z
Wd
Wk
1
1
feet platform
X / Y
Z
Wk
0.25
0.4
backrest
X*
Y
Z*
Wc
Wd
Wd
0.8
0.5
0.4
standing
feet platform
X / Y
Z
Wd
Wk
1
1
recumbent
under pelvis
X (vertical)
Y / Z (horizontal)
Wk
Wd
1
1
under head
X (vertical)
Wj
1
In railway vehicles:
standing
sitting
recumbent
feet platform
seat/backrest/feet
support. surface,
pelvis/head
X / Y / Z
Wb
1
In buildings:
undefined
in buildings
X / Y / Z
Wm
1
Table 2: Weighting filters and factors for whole-body vibration
* Please note that the Z axis points along the backbone for all measurements. For
measurements at the backrest with a seat pad accelerometer the sensor will always be
in a vertical position with Z perpendicular to the backbone. However, to compensate the
VM31 automatically swaps the X and Z axis for backrest measurement.
CV:31A Settings for Whole-Body vibration measurements
Whole-Body Measurement with RMS Values
For the evaluation of hand-arm vibration it is recommended
to measure both the interval RMS values of X/Y/Z and their
vector sum aW. The VM31 measures these four values
simultaneously. In addition it shows the maximum running
RMS (Maximum Transient Vibration Value, MTVV) which may
indicate the presence of shock vibration.
The following section explains the measurement of whole-
body vibration in terms of health risks. Health evaluation is
done with weighting filter Wd for X/Y and Wk for Z and with
weighting factors 1.4 for X/Y and 1.0 for Z.

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Appendix 2 show the frequency response curves of the filters Wd and Wk in VM31 and
the tolerance bands in compliance with ISO 8041.
In addition to health evaluation the VM31 also supports measurements regarding
comfort. This type of measurement uses other postures, sensor positions and different
frequency weightings but the general procedure is the same.
Appendix 2 shows the frequency response curves of the weighting filters for comfort
measurements.
To start whole-body vibration measurement for the assessment of health risks open the
main menu by pressing F3, and select “Measuring mode” / “Human vibration” / “Whole-
body ISO 2631” / “Health”.
From this menu you will return to the measuring screen. You may press F1 to check
your settings.
Press the key ◄to switch from VDV to RMS if necessary.
If the worker being tested is sitting in the right position and vibration exposure has
started, press the key ►key (Reset) to:
•reset the RMS values of X/Y/Z, the vector sum aWand MTVV to zero
•restart the measurement timer.
Always press Reset before a measurement to establish the defined start
conditions.
The RMS values of X/Y/Z and the vector sum are averaged over the entire measuring
time. That's why fluctuation becomes less the longer the measurement takes. After a
while short shock pulses have almost no influence on the the displayed results
anymore.
The recommended measuring time for hand-arm vibration is at least 2 minutes. To alert
you, the timer in the upper right corner remains red until 2 minutes have elapsed.
“OVERLOAD” is indicated instead of the measuring values if the current magnitude is
too high. Even if the overload condition was of short duration the measured interval
RMS value may become invalid because of missing samples.
An overload event during the entire averaging time is indicated by “OVL!” in the upper
right corner after the date. This warning can be deleted by pressing the key ►(Reset).
After measurement you may save the results by pressing the key ▼. Measurement
should be either continued or finished immediately before pressing the key, otherwise
the measuring values will drop slowly. You will be asked to enter two lines of ten capital
letters or numbers as a comment.
Use the keys ◄▲▼► to select characters and to change the input position. Press F1 to
change the input line.
Measurement can be finished before entering a comment because the results will have
already been saved by pressing the key ▼.

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Measurements can only be saved if a sensor is detected at X/Y/Z and if there is no
overload condition. In these cases the CV:31A will display “Sensor error” or “Overload
occurred” instead of saving in order to avoid invalid recordings.
If an overload occurred since the last reset (“OVL!” in upper right corner) the
instrument will show a warning “Overload occurred after last reset! Save anyway?”.
If you want to measure several partial exposures you may now do further
measurements.
For the calculation of vibration exposure A(8) and to store results on a PC the Excel
macro file cv31.xlsm is provided.
Whole-Body Vibration Measurement with VDV Values
The CV:31A also allows whole-body vibration to be measured as vibration dose values
(VDV). These are fourth power mean values. VDV is more sensitive to peaks. The
measuring unit of VDV is m/s1,75.

󰇛󰇜



Equation 11
Press the key ◄to switch from RMS to VDV and vice versa.
The same weighting filters and factors as for RMS
measurement are used. You may press F1 to check your
settings.
The device displays VDV values for the directions X/Y/Z. In
addition the highest of the three axis values (Max. VDV) and
the highest VDV since the last reset (Max. abs.) are displayed.
VDV measurements need to be started by pressing the key ►
(Reset).
Measurements can be saved by pressing the key ▼(see page
17).
The Excel file vm31.xlsm also allows the calculation of vibration exposure based on VDV
measurements.

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Seat Effective Amplitude Transmissibility (SEAT)
The Seat Effective Amplitude Transmissibility (SEAT) value is
the ratio of the vibration experienced on top of the seat and
the vibration that one would be exposed to when sitting
directly on the vibrating floor.
Both vibration magnitudes are measured in the vertical
direction (Z) only. SEAT values are widely used to determine
the vibration isolation efficiency of a seat.
The fourth channel (A) of the CV:31A in combination with a
uniaxial accelerometer can be used to determine SEAT values.
It is connected via a sensor cable to the left socket (see
Figure 1). The fourth channel is named “A” on the display. The sensitivity of a TEDS
sensor will be automatically detected. With a non-TEDS sensor it needs to be entered
manually.
Select “Whole-body ISO 2631” / “Unweighted” for channels X/Y/Z. Channel A does not
have frequency weightings. Its frequency range (-3 dB) is 0.8 to 250 Hz. The RMS or
VDV of channel A is displayed below channels X/Y/Z.

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General Vibration Measurement
In addition to its human vibration ranges the CV:31A can measure:
•Vibration acceleration from 0.1 to 2000 Hz and 1 to 1000 Hz,
•Vibration velocity from 1 to 100 Hz, 2 to1000 Hz and 10 to 1000 Hz,
•Vibration displacement from 5 to 200 Hz.
Press F3 to open the menu, select “Measuring mode” and use the keys ▲▼ to select
the vibration range.
You can switch the measuring screen from RMS to peak display by pressing the key ◄.
Please note that the RMS and peak values in the general vibration ranges are computed
over the last display cycle (not over a long period).
A display cycle can be between 1 and 4 seconds, depending on the frequency range.
RMS or peak values are shown for X/Y/Z. There will also be an RMS or peak value for
channel A if you have connected a sensor to this input.
Channel A always measures acceleration. Its frequency range depends on the mode
selected for X/Y/Z (Table 3).
Mode X/Y/Z
Frequency range X/Y/Z
Frequency range A
Acceleration
0.1 to 2000 Hz
0.1 to 2000 Hz
Acceleration
1 to 1000 Hz
3 to 1000 Hz
Velocity
1 to 100 Hz
1 to 250 Hz
Velocity
2 to 1000 Hz
2.5 to 750 Hz
Velocity
10 to 1000 Hz
2.5 to 750 Hz
Displacement
5 to 200 Hz
1 to 250 Hz
Table 3: Frequency ranges of channel A
Vibration velocity is computed by single integration of the acceleration signal,
displacement by double integration.
Due to integration there is a strong attenuation at high frequencies which limits the
measurable frequencies, particularly for displacement.
Low frequencies, including noise, are strongly amplified. High pass filtering is inevitable.
The frequency response curves of the general vibration ranges can be seen in Figures
24, 25 and 26.

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Figure 24: Frequency ranges of vibration acceleration
Figure 25: Frequency ranges of vibration velocity

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Figure 26: Frequency range of vibration displacement (upper end due to resolution)
Vibration quantity and frequency range can be checked by pressing F1.
Below the 3 (or 4) RMS or peak values you can see two combined values which are
calculated from X/Y/Z. These are:
•in RMS mode the vector sum of X/Y/Z (aw(Vec)) and the highest RMS value (Max.
abs.) since the last press of the Reset key ►.
•in peak mode the highest of the currently displayed XYZ peak values (Max. XYZ)
and the highest peak value (Max. abs.) since the last Reset ►.
Maximum values are displayed in the colour of the channel where they occurred.
Pressing the Reset key ►
•deletes the maximum values and
•restarts the measuring timer
Measurements can be saved by pressing the key ▼

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Data Logger
The CV:31A can automatically record measuring data for
channels X/Y/Z at the speed of the display refresh rate.
It can log running RMS or peak values. Logging can be
useful in combination with human vibration measurement
to detect single vibration or shock events during a longer
measuring period.
For example, the log file can help to identify shocks caused
by putting down a machine tool.
Such single events can significantly change the interval
RMS value without being relevant in terms of health risks.
The instrument stores data and time along with the three values of X/Y/Z. The recorded
measurements are filtered with the same weighting or band filter used for the dis-
played measurements. Channel A is not recorded.
Please note that the logged data is calculated only for the last display interval (approx.
1 s). For human vibration, however, interval RMS values are measured which are
integrated over the entire measuring time.
Therefore there may be differences between the displayed and the recorded values.
To start the data logger press F3 to open the main menu, select
“Data memory” / “Data logger” / “Start logging” (Figure 28). You
will be prompted to select a file number.
This number will be used later on to identify the log file. The
memory can hold 100 log files. File numbers can be 00 to 99.
If the selected file should already contain data you will be asked to delete it. Now you
select whether RMS or peak values are to be logged. Press OK to leave the menu and to
start logging. After a settling time the unit will start to record measurements.
The active log mode is indicated in the upper right display corner by the text “LOG!”
(Figure 29).
Logging can be stopped by pressing F3.
Please note that the data logger will be halted while data is transferred via the USB
interface. This may result in missing records. The automatic shut-off function is not in
use while logging.
The maximum number of records per log file is 32,000 which is sufficient for about 10
hours of continuous recording.

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Frequency Analysis
The CV:31A provides a simple FFT function for the
detection of main frequencies. It displays a 125 line peak
spectrum of acceleration.
Press F3 and select “Frequency analysis” to open the FFT
screen (Figure 27). You see the frequency components of
channels X/Y/Z1in their respective channel colors.
The line above the diagram shows frequency and
magnitude of the longest spectral line.
The keys ◄► move the cursor. Below the diagram you
can see the cursor readout.
Press F1 or F2 to change the frequency range. Four
ranges are selectable:
•3 to 244 Hz
•7 to 488 Hz
•15 to 977 Hz
•30 to 1954 Hz
Pressing the key ▼saves the spectrum. The CV:31A can store up to 1000 FFT
measurements.
To view stored FFTs press F3 to open the menu and select “Data memory” /
“View/delete FFT data”. Use the keys ▲▼ to select the desired FFT. A cursor function
using the keys ◄► is also available.
Stored FFT data can be transferred to a PC. There is no FFT function for channel A.
Instrument Settings
Sensor Calibration
If a connected sensor is not TEDS compatible, the
CV:31A will automatically open the menu “Transducer
calibration”.
It can also be opened from the menu “Device settings”
to check or to change the entered sensitivities.
Sensitivities are entered one after another for channels
X/Y/Z and, if connected, for channel A. The sensitivity
value is a five-digit number with the measuring unit
mV/ms-2. You find the correct values in the transducer
calibration sheet.
The decimal point can be shifted by pressing F1. The
allowed sensitivity range is 0.800 to 12.000 mV/ms-2 or 8.00 to 120.00 mV/ms-2.

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Time & Date
When saving measurement values the date and time
need to be correctly recorded. To set the date and time,
open the main menu by pressing F3 and select “Device
settings”. Within this sub menu select “Date and time”.
Using keys ▲▼ you can adjust the chosen value. Upon
reaching the maximum value, e.g. in the 23rd hour, the
counter starts again from the beginning. Press ◄► to
skip between hour, minute, month, day and year. The
date takes account of the leap year. It is, however,
important to ensure that no invalid day-month
combinations are entered.
Additionally, clock inaccuracy can be corrected. This can
be done using the setting at “Cal.” in ppm (parts per
million). The clock frequency can be increased with positive values and decreased with
negative. The sign changes to minus at +254 ppm.
Shut-off Timer
The CV:31A has a shut-off timer to help prolong the battery
operating life. To set the shut-off timer, open the main
menu by pressing F3, select “Device settings” and “Shut-off
timer”.
Press keys ▼▲ to select the timer duration from the options
1, 5, 15 and 60 minutes. To deactivate the timer select
('none'). The switch off timer starts to run after the last
press of a button. If a button is pressed the timer will restart
the count down for the set duration.
Battery Type
While non-rechargeable batteries have a cell voltage of 1.5
V, NiMH rechargeable batteries deliver only 1.2 V per cell.
The CV:31A battery indicator can be adjusted to both
voltages. To adjust the voltage, open the main menu by
pressing F3, select “Device settings” and “Battery type”.
Within the sub-menu select “Battery type” pressing ▼
selects between “Alkaline”(non-rechargeable, 1.5 V) or
“NiMH” (rechargeable, 1.2 V).
If the power supply drops below 3.3 V when using alkaline
batteries or below 3 V with rechargeable batteries, the
battery indicator becomes red.
Further measurements can be taken until the power supply reaches 2.8 V in keeping
with the device specifications. At this point the battery level indicator is completely
empty and the device switches itself off automatically.