MMF VM30-H User manual

Instruction Manual
*How to find the version of your instrument: page 47
Manfred Weber
Metra Mess- und requenztechnik in Radebeul e.K.
Meissner Str. 58 - D-01445 Radebeul
Phone [phone] ax [phone]
Email: Info@MM .de Internet: www.MM .de
Human
Vibration
Meter
VM30-H
rom Version 02.02.xxx.xxx*

The latest edition of this document can be found under:
http://www.mmf.de/product_literature.htm
© Manfred Weber
Metra Meß- und Frequen technik in Radebeul e.K.
May/ 12 #193

Contents
1. Purpose....................................................................................................................................1
2. The Instrument at a Glance.......................................................................................................1
3. Menus......................................................................................................................................2
4. Fundamentals of Human Vibration Measurement ...................................................................4
4.1. Introduction.......................................................................................................................4
4.2. EU Directive 2002/44/EC..................................................................................................4
5. Human Vibration Measurement with the VM30-H..................................................................7
5.1. Switching On and Connecting the Sensor .........................................................................7
5.2. Hand-Arm Vibration Measurement with the VM30-H......................................................8
5.2.1. Measuring Points for Hand-Arm Vibration ................................................................8
5.2.2. Settings on the VM30-H.............................................................................................9
5.2.3. Reporting of Measuring Results................................................................................10
5.3. Whole-Body Vibration Measurement with the VM30-H.................................................11
5.3.1. Measuring points for Whole-Body Vibration............................................................11
5.3.2. Settings at the VM30-H............................................................................................12
5.3.3. Evaluation of Health Risks........................................................................................14
5.3.4. Comfort Evaluation...................................................................................................15
5.3.5. Reporting of Measuring Results................................................................................15
6. Switching the Instrument On and Off.....................................................................................16
7. Sensor Input...........................................................................................................................16
8. Display...................................................................................................................................17
9. Signal Setup...........................................................................................................................18
9.1. Vibration Quantity...........................................................................................................18
9.2. Filters..............................................................................................................................18
9.2.1. Weighting Filters......................................................................................................18
9.2.1.1. Weighting Filter Wb ..........................................................................................18
9.2.1.2. Weighting Filter Wc ..........................................................................................19
9.2.1.3. Weighting Filter Wd...........................................................................................19
9.2.1.4. Weighting Filter We...........................................................................................20
9.2.1.5. Weighting Filter Wg...........................................................................................20
9.2.1.6. Weighting Filter Wh...........................................................................................21
9.2.1.7. Weighting Filter Wj...........................................................................................21
9.2.1.8. Weighting Filter Wk...........................................................................................22
9.2.1.9. Weighting Filter Wm..........................................................................................22
9.2.1.10. Combined Weighting Filters............................................................................23
9.2.2. Band-Pass Filters......................................................................................................23
9.3. Display Modes.................................................................................................................24
9.3.1. Running RMS...........................................................................................................24
9.3.2. Maximum Transient Vibration Value (MTVV)........................................................24
9.3.3. Interval RMS (A(T)).................................................................................................24

9.3.4. Estimated Vibration Dose Value (eVDV).................................................................25
9.3.5. Vibration Total Value (Ahv).....................................................................................26
9.3.6. Peak Value (PEAK)..................................................................................................26
9.3.7. Maximum Peak Value (PEAK↑)...............................................................................27
9.3.8. Crest Factor (CREST)...............................................................................................27
9.4. Saving User-Defined Setups............................................................................................27
9.5. Loading User-Defined Setups..........................................................................................28
10. Measuring Range and Autoranging......................................................................................28
11. Overload Indication..............................................................................................................29
12. Saving Measuring Results....................................................................................................29
12.1. Manual Recording by the SAVE Key............................................................................29
12.2. Automatic Recording in the Data Logger Mode............................................................30
12.3. Viewing Saved Measurements on the Display...............................................................30
13. Data Transmission to the PC................................................................................................31
13.1. Preparing the Import of Data into Excel........................................................................31
13.2. Importing VM30-H Data with the Excel Macro ...........................................................31
13.3. Calculation of the Daily Exposure Value A(8)..............................................................33
13.4. Function of the Excel Macro ........................................................................................36
13.5. Transmission to PC by a Terminal Program..................................................................37
14. Time and Date......................................................................................................................38
15. Calibration and Function Check...........................................................................................39
15.1. Entering Transducer Sensitivities .................................................................................39
15.2. Sensitivity Calibration by a Vibration Calibrator ..........................................................39
15.3. Mechanical Calibration..................................................................................................40
15.4. Electrical Calibration.....................................................................................................40
15.5. Function Check..............................................................................................................43
16. Other Settings ......................................................................................................................43
16.1. Beep Sound On / Off.....................................................................................................43
16.2. Automatic Shut-Off Timer.............................................................................................44
16.3. Battery Type..................................................................................................................44
16.4. Factory Settings.............................................................................................................44
16.5. Baud Rate......................................................................................................................44
17. Serial Interface.....................................................................................................................44
18. Signal Output.......................................................................................................................44
19. Power Supply.......................................................................................................................45
19.1. Battery Operation..........................................................................................................45
19.2. External Supply.............................................................................................................46
20. Loading Default Settings......................................................................................................46
21. Hardware Reset....................................................................................................................46
22. Hardware and Firmware Versions .......................................................................................47
23. Firmware Update .................................................................................................................47
24. Questions and Answers........................................................................................................49

25. Technical Data.....................................................................................................................50
Appendix: Warranty
Declaration of Conformity

1. Purpose
Thank you for choosing a vibration meter from Metra!
The VM30-H was developed for the measurement of human vibrations. In addition, it is suited
for many other fields of vibration measurement such as machine vibration, building vibration or
quality control.
The instrument can measure triaxial hand-arm vibration to EU directive 2002/44/EC based on
ISO 5349 and whole-body vibration to ISO 2631. It conforms to the latest edition of ISO 8041
for measuring instrumentation for human vibration.
Particular attention has been paid to simple operation, compact design and long battery
operating time.
2. The Instrument at a Glance
Figure 1: Key functions
Figure 2: Connections
1
Sensor
input
External
supply
Analog
output
RS-232
interface
Battery cover
SAVE: Record measuring values
ESC: Leave menues without change,
Reset maximum and long-term values
LOAD: Load user-defined setups
LOCK: Key lock on / off
MENU: Setup
LIGHT: Display backlight
IN O: Memory occupancy, time, date, version
RANGE: Change / save signal settings
ON / O : On (hold 2 s) / Off
Press strongly
to open the
battery compartment

Figure 3: Battery compartment and reset button
3. Menus
2
Battery compartment
Reset
MENU
1/8: Gain Gain Range X
Main Menu
Select time unit Log duration
3/8: View memory
Manually by SAVE key with / without comment with / without time with / without date
Log interval
(password protected)
Gain Range Y Gain Range Z
by data logger
2/8: Recording setup
Log file title
4/8: Erase memory
5/8: Time and date
6/8: Load defaults
7/8: Sensor
By vibration calibrator
By transducer sensitivity
8/8: Device Settings 1/6: Beeper on / off
2/6: Shut-off timer
3/6: Battery type
4/6: actory settings
5/6: Baud rate
Edit this sensor?Sensor selection
no
yes
Nominal sensitivity
1
10
mV/ms²
Entry after sensor connection
Sensor name
X/Y/Z
6/6: irmware update

3
Si nal Setup Menu
RANGE
Human Vibration
Acceleration
Velocity
Displacement
Selection of the
vibration quantity
ilter Band filters and
weighting filters for
selected vibration
quantity
Running RMS (1 s)
Max. running RMS
Interval RMS
stimated vibr. dose
Total vibration value
Peak value (1 s)
Max. peak value
Crest factor
RMS
MTVV
A(T)
eVDV
Ahv
PEAK
PEAK
CREST
Enter Ahv k factors
Save settings? No
Yes
Factors kx, ky und kz
for Ahv only
Save as: Setup No. Save as setup
number 0 to 9
Enter setup name Setup name
20 characters

4. Fundamentals of Human Vibration Measurement
4.1. Introduction
Vibrations acting on the human body are called human vibration. The main purpose of
measuring human vibration is the prevention of health risks and the evaluation of comfort, for
example in vehicles.
Two categories are distinguished:
•Hand-Arm Vibrations, which are induced via the hands into the body. They may cause,
for example, circulatory disorder, bone, joint or muscle diseases.
•Whole-Body Vibrations, acting via the buttocks, the back and the feet of a sitting person,
the feet of a standing person or the back and the head of a recumbent person. Such
vibrations may cause backache or damage to the spinal column.
Both types of human vibration are described in international standards:
•ISO 5349 - Measurement and evaluation of human exposure to hand-transmitted vibration
•ISO 2631 - Evaluation of human exposure to whole-body vibration
•ISO 041 - Human response to vibration. Measuring instrumentation
•ISO 662 - Hand-held portable power tools - Measurement of vibrations at the handle
•ISO 6954 - Guidelines for the measurement, reporting and evaluation of vibration with
regard to habitability on passenger and merchant ships
•ISO 10056 - Measurement and analysis of whole-body vibration to which passengers and
crew are exposed in railway vehicles
•ISO 10326 - Laboratory method for evaluating vehicle seat vibration
Practical advice for measurement and evaluation of human vibration can be found in VDI 2057.
The subject of human vibration has gained particular importance in Europe since the directive
2002/44/EC came into effect. It specifies the duties of employers with regard to workers
protection.
4.2. EU Directive 2002/44/EC
The following text is an abstract of Directive 2002/44/EC of the European Parliament and of the
Council dated June 25 2002. The complete text can be downloaded from
http://eur-lex.europa.eu/
The directive lays down minimum requirements for the protection of workers from the risks
arising from vibrations. Manufacturers of machines and employers should make an adjustment
regarding risks related to exposure to vibration.
The directive lays down the following limit values:
4

Hand-Arm Vibration Whole-Body Vibration
Exposure Action Value 2.5 m/s² 0.5 m/s²
Exposure Limit 5 m/s² 1.15 m/s²
Once the exposure action value is exceeded, the employer shall establish and implement a
program of technical and and organi ational measures intended to reduce to a minimum
exposure to mechanical vibration, taking into account in particular:
•Other working methods that require less exposure to mechanical vibration
•Appropriate work equipment of ergonomic design, producing the least possible vibration
•Provision of auxiliary equipment that reduces the risk of injuries, such as protective gloves
or special seats
•Appropriate maintenance programs for work equipment
•Design and layout of workplaces
•Adequate information and training to instruct workers to use work equipment correctly and
safely
•Limitation of the duration and intensity of the exposure
•Work schedules with adequate rest periods
•Provision of clothing to protect workers from cold and damp
In any event, workers shall not be exposed above the exposure limit value. If this should be the
case, the employer shall take immediate action to reduce exposure below the exposure limit
value.
The methods used may include sampling, which must be representative of the personal exposure
of a worker to the mechanical vibration in question.
The assessment of the level of exposure to vibration is based on the calculation of daily
exposure A( ) expressed as equivalent continuous acceleration over an eight-hour work period.
For the determination of A(8) it is not necessary to measure over eight hours. It is sufficient to
make short-term measurements during representative work steps. The results are normali ed to
eight hours. Daily exposure is calculated as follows:
Equation 1
where
awe is the energy equivalent mean value of the frequency weighted acceleration during the
exposure
Te is the total duration of exposure during one work day
T0is the reference duration of 8 hours
5
A8=awe

Te
T0

Daily exposure may consist of several activities with different vibration magnitudes. This can be
the case if there are longer interruptions in the work process, if the work equipment or its way
of use is changed. Resulting daily exposure is calculated:
A8=

1
T0
∑
i=1
n
awi
2Ti
Equation 2
where
awi is the energy equivalent mean value of the frequency weighted acceleration of activity i
n is the number of activities
Tiis the duration of activity i
T0is the reference duration of 8 hours
For hand-arm vibration the energy equivalent mean value awe is calculated to ISO 5349. It is
the square root of the sum of the squares (vector sum) of the interval rms values awx, awy and aw .
The interval rms values are measured as the accelerations in three orthogonal directions with
the weighting filter Wh. This vector sum is often called Total Vibration Value ahv :
awe =ahv=

awx
2awy 2awz 2
Equation 3
In the case of machines which need to be held with both hands, measurements must be made on
each hand. The exposure is determined by reference to the higher value of the two.
For whole-body vibration the energy equivalent mean value of acceleration awe (interval rms) is
measured separately on three orthogonal axes to ISO 2631-1. For seated persons the following
weighting filters and multiplying factors are applied:
X axis: Filter WdMultiplying factor kx = 1.4
Y axis: Filter WdMultiplying factor ky = 1.4
Z axis: Filter WkMultiplying factor ky = 1
The highest one of the three values is inserted as awe in the calculation of A(8).
If no dominant axis of vibration exists, the energy equivalent mean value of acceleration awe
may also be calculated as vibration total value ahv, where the multiplying factors kx, ky and k are
to be used:
awe =ahv=

kx
2awx 2ky 2awy 2kz 2awz 2
Equation 4
6

5. Human Vibration Measurement with the VM30-H
5.1. Switchin On and Connectin the Sensor
Switch on the VM30-H by pressing the ON/OFF key for at least two seconds (compare p. 16).
Plug in the sensor cable or unplug it shortly to activate the sensor detection. Select the
connected sensor (hand-arm or whole-body) using the ▲▼ keys. If the VM30-H was calibrated
already with the selected sensor, you may answer the question “Edit this sensor?” with “No”.
Otherwise select “Yes”, choose the nominal transducer sensitivity (1 or 10 mV/m/s-2) and enter
in the menu “By transducer sensitivity” the sensitivities from the supplied calibration certificate
for X, Y and Z direction. Numbers can be changed by the ◄▲▼► keys. Confirm each entry
with OK and leave the menu with ESC.
The sensitivities of both sensor types remain stored in the instrument (see p. 39). They must not
be entered again if the sensor is changed.
Figure 4: Sensors for hand-arm and whole-body vibration
7

5.2. Hand-Arm Vibration Measurement with the VM30-H
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.
5.2.1. Measurin Points for Hand-Arm Vibration
The sensors should be attached as close as possible to the place of entry into the hand, however,
they must not interfere with the work process. Measurement shall 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, Metra offers some mounting accessories for curved surfaces.
Figure 5: Mounting accessories for hand-arm vibrations models 140 and 142
The adapter model 140 is attached with a plastic cable strap. Model 142 is pressed onto the
handle by the hand.
Very important is a tight contact between sensor and machine. Any motion of the sensor would
distort the measurement.
Figure 6 shows the axis directions for the attachment of the sensor at the handle. For cylindric
handles the Y direction point in the direction of the handle axis. The Z axis is approximately the
extension of the third metacarpal bone.
8

5.2.2. Settin s on the VM30-H
For hand-arm vibrations it is recommended to report both the interval RMS for each axis and
vibration total value (Ahv). Therefore both measurements are described in this section.
Select first the measuring ranges for X, Y and Z. A good method is starting with the most
sensitive range. Press the MENU key and open the menu “1/8: Gain” with OK. Set the
measuring ranges for X, Y and Z to 12 m/s² by the ▲▼ keys and confirm each entry with OK
(see p. 28).
Presse the key ▲ (Range) and chose with the ▲▼ keys “human vibration”. Press OK and select
the weighting filter “H/A Wh”. Confirm with OK. Hand arm vibration is always measured with
the weighting filter Wh (compare p. 21).
Select in the following menu the display mode “A(T)” for interval RMS (p.24).
Ignore the question “Save settings?” by pressing ESC.
Measurement is started by pressing the ESC key. This resets the averaged RMS values and the
timer to ero. The start of measurement must be after the start of vibration exposure. Otherwise
the result, averaged over the entire measuring time, would be wrong. The duration of
measurement shall represent a typical work process. Usually 10 seconds are sufficient for hand-
arm vibrations. The elapsed measuring time can be seen in the upper left display corner. A
sufficiently long duration of measuerement is reached if the measuring values do not change
anymore.
If an overload should occur during measuerement, the message “OVERLOAD” will appear
instead of the measuring value (compare p. 29). The measuring result is invalid even if there
was only a short overload. For this reason the display will show “Overload” as soon as an
overload occurs on any channel. This message can be erased only after pressing ESC.
If an overload is indicated, increase the measuring range for the respective channel, wait a few
seconds until the instrument has settled and start a new measurement by pressing ESC. The
measuring range shall not be higher than necessary in order to provide maximum display
resolution.
9
Figure 6: Coordinate system of the hand (from ISO 5349-1)

After a sufficient duration of measurement you may save the result by pressing SAVE. The
vibration exposure must persist in the moment of saving. Please make sure that the instrument is
in the manual save mode. If necessary, select in the menu “2/8: Recording setup” the mode
“manually by SAVE key”. Otherwise the data logger will start after the SAVE key. You may
also choose whether you like to save date and the time and a 20 characters comment with the
result. A comment text can be entered with the ◄▲▼► keys and OK.
For the measurement of vibration total value Ahv press again the ▲ (Range) key, select
“human vibration” and the weighting filter “H/A Wh”. Select the display mode “Ahv”. You will
be asked for the multiplying factors kx, ky and k . For hand-arm measurement they have the
value “1.0” (see p. 26).
The instrument will display only one value Ahv, which is the vector sum of three axes. Start the
measurement by ESC and measure approximately for the same time as for interval RMS.
With the gain settings made before there should be no overload.
Save the measurement with the SAVE key.
If the vibration exposure consists of different sections, more than one measurements may be
required.
For the calculation of daily exposure A( ) and for reporting the results Metra provides an Excel
sheet with direct data import from the serial interface. A description can be found on page 31.
Notice: You may simplify the setup of the VM30-H by using pre-defined setups. Press the ▼
(LOAD) key to choose from 10 stored setups. In the original configuration setup no. 0 contains
the settings for the interval RMS of hand-arm vibration and setup no. 1 for vibration total value
(see p. 27).
5.2.3. Reportin of Measurin Results
The report to ISO 5349-2 should include the following information:
•General information:
- Client
- Purpose of measurement
- Date
- Name of operator
- Name of evaluating person
•Environmental conditions:
- Location
- Temperature
- Humidity
- Noise
•Daily operating sequence for the activities under test:
- Description of activities
- Used machine and tools
- Time flow of activities (work time, breaks)
- Basis for the used exposure time (e.g. job norm)
10

•Details of the vibration source:
- Technical description of the machine
- Type and Model
- Age and maintenance condition
- Weight of hand-held part or tool
- Vibration reduction measures, if applicable
- Type of handle
- Automatic controls (e.g. torque control)
- Power rating
- Revolution speed, number of blows
- Type of used tools
•Measuring equipment:
- Instrument and sensor types, serial numbers
- Traceable calibration
- Date of last calibration
- Results of function check
•Measuring conditions:
- Measuring points and directions (sensor axes) with dimensional drawing
- Mounting method of the sensor
- Weight of the sensor
- Operating condition
- Arm and hand posture, left / right handed
- Other data (e.g. hand pressure force)
•Measuring results:
- Frequency weighted interval RMS values of acceleration awx, awy and aw . for three
orthogonal directions, preferably for each activity
- Measuring duration for each activity
•Results for daily exposure A(8):
- Vibration total values for each activity
- Duration Ti of vibration exposure for each activity
- Partial exposure Ai(8)
- Daily exposure A(8)
- Assessment of measurement uncertainty
5.3. Whole-Body Vibration Measurement with the VM30-H
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 and for impacts, like car crashes. Vibrations transmitted
via the hands have been described separately in the previous section.
5.3.1. Measurin points for Whole-Body Vibration
Whole-body vibration is usually measured with seat pad accelerometers. These are triaxial
pie oelectric sensors built into a flat rubber pad which adapt themselves to the interface between
the vibration source and the test person.
11

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 7 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 on
page 23).
5.3.2. Settin s at the VM30-H
For whole-body vibration interval RMS is measured for each coordinate direction.
Select first the measuring ranges for X, Y and Z. A good method is starting with the most
sensitive range. Press the MENU key and open the menu “1/8: Gain” with OK. Set the
measuring ranges for X, Y and Z to 12 m/s² using the ▲▼ keys and confirm each entry with
OK (see p. 28).
Presse the key ▲ (Range) and select “human vibration” with the ▲▼ keys.
The next step is selecting the weighting filter with ▲▼. There are different weighting filters for
each vibration entry point. The weighting filters are marked with Wx. The filter curves can be
seen in Figure 8.
12
Figure 7: Coordinate systems for whole-body vibration to ISO 2631
Z
Y
Z
Y
Z
X
Y
Z
X
X
Y
X
Y
Z
X

The weighting filter to be used depends on the point where the vibrations enter the human body
and on the coordinate direction (Table 1). A difference is also made between the evaluation of
health risks and comfort.
Evaluation of health risks
Posture Location Direction Frequency
weighting factor
sitting seat surface X / Y
Z
Wd
Wk
1.4
1
Evaluation of Comfort
sitting
seat surface X / Y
Z
Wd
Wk
1
1
footrest X / Y
ZWk
0.25
0.4
backrest
X*
Y
Z*
Wc
Wd
Wd
0.8
0.5
0.4
standing footrest X / Y /
Z
Wd
Wk
1
1
recumbent pelvis X (vertical)
Y / Z (hori ontal)
Wk
Wd
1
1
head X (vertikal) Wj1
undefined in buildings X / Y / Z Wm1
Table 1: Application of the weighting filters *see notice on page 23
Only the filters Wd for X and Y directions and Wk for Z direction are relevant for the evaluation
of health risks. They are found in the filter menu as combination “Wd+Wk”.
13
Figure 8: Frequency weightings for whole-body vibration
0,01
0,1
1
10
0,1 1 10 100 1000
Hz
Wc
Wd
We
Wj
Wk
Wm

After this choose the display mode “A(T)” (interval RMS, p.24).
Ignore the question “Save settings?” by pressing ESC.
Measurement is started by pressing the ESC key. This resets the averaged RMS values and the
timer to ero. The start of measurement must be after the start of vibration exposure. Otherwise
the result, averaged over the entire measuring period, would be wrong. The duration of
measurement shall represent a typical exposure interval. It should be at least 2 minutes. The
elapsed measuring time can be seen in the upper left display corner. A sufficiently long duration
of measuerement is reached if the measuring values do not change anymore.
If an overload should occur during measuerement, a message “OVERLOAD” will appear
instead of the measuring value (compare p. 29). The measuring result is invalid even if there
was only a short overload. For this reason the instrument will also display “Overload” in the
upper line as soon as an overload occurs on any channel. This message can be erased only by
pressing ESC.
If an overload is indicated, increase the measuring range for the respective channel, wait a few
seconds until the instrument has settled and start a new measurement by pressing ESC. The
measuring range must not be higher than necessary in order to provide maximum display
resolution.
After a sufficient duration of measurement you may save the result by pressing SAVE. The
vibration exposure must persist in the moment of saving. Please make sure that the instrument is
in the manual save mode. If necessary, select in the menu “2/8: Recording setup” the mode
“manually by SAVE key”. Otherwise the data logger will start after pressing the SAVE key.
You may also choose whether you like to save date and the time and a 20 characters comment
with the result. A comment text can be entered with the ◄▲▼► keys and OK.
If the vibration exposure is divided into different sections, measurements have to be performed
for each section.
Notice: You may simplify the setup of the VM30-H by means of pre-defined setups. Press the
▼ (LOAD) key to choose from 10 stored setups. In the original configuration setup no. 2
contains the settings for the interval RMS with the filters Wd and Wk for the seat surface and
setup no. 5 for the interval RMS with the filters Wd and Wc for the backrest (see p. 27).
5.3.3. Evaluation of Health Risks
The calculation of daily vibration exposure A(8) is based on the highest one of the three interval
RMS values (X/Y/Z) measured for each exposure section. The interval RMS value has to be
multiplied with the K factor depending on direction and weighting filter according to Table 1.
Example: For health risk evaluation with Wd and Wk the correction factors are KX,Y = 1.4 and
KZ = 1.
Notice: The interval RMS values displayed by the VM30-H do not include K factors.
The selected maximum interval RMS value multiplied with the appropriate K factor is inserted
as awe in Equation 1 or for more than one exposure sections as awi in Equation 2.
If the interval RMS values of two axes have approximately the same magnitudes, daily
vibration exposure A(8) can also be calculated based on vibration total value Ahv. In this case
the K factors are taken into account for Ahv calculation by the VM30-H.
14

5.3.4. Comfort Evaluation
The subjective perception of vibrations is determined by a perception limit and a pain threshold.
Table 2 gives a rough orientation for the relationship between vibration level and perception.
However, perception strongly varies with the test person and depends, in addition, on other
influences like age, gender, health condition, attentiveness, type of activity, temperature and
noise.
RMS of frequency weighted acceleration
m/s² Perception
<0.01 not perceptible
0.015 perception limit
0.02 just perceptible
0.08 well perceptible
0.315 strongly perceptible
>0.315 very strongly perceptible
Table 2: Relationship between the RMS of weighted acceleration and the subjective perception
in the case of sinusoidal vibration (VDI 2057)
Well-being under the influence of vibration has to be evaluated situationally. So the vibration of
a passenger vehicle is rather regarded as disturbing than the vibration of a building machine.
Although there is no general relationship between well-being and acceleration, the interval RMS
can be measured in three directions and reported for comparisons. For some purposes, like
passenger transport, vibration total value Ahv may be measured.
5.3.5. Reportin of Measurin Results
The report of the measuring results should include the following information:
•Client
•Purpose of measurement
•Location, date and time
•Name of test person
•Name of evaluating person
•Description of activity
•Description of exposure sections
•Vibration source, e.g. type of machine or vehicle
•Exposure directions of vibration
•Body posture (sitting, standing or recumbent)
•Transmitting components between vibration source and test person
•Number, location and mounting of sensors
•Instrument type (model, serial number, calibration, uncertainty)
•Results: Interval RMS values awT of frequency weighted acceleration separately for each
direction and each location, duration of measurement, duration of exposure or exposure
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