MMF VM31-M User manual

Instruction Manual
Manfred Weber
Metra Mess- und Frequenztechnik in Radebeul e.K.
Meissner Str. 58 - D- 1445 Radebeul
Tel. [phone] Fax [phone]
Email: [email protected] Internet: www.MMF.de
Human-
Vibration
Analyzer
VM31
(Valid from version 003.023)

Published by:
Manfred Weber
Metra Mess- und Frequenztechni in Radebeul e.K.
Meißner Str. 58
D-01445 Radebeul
Tel. [phone]
Fax [phone]
Email [email protected]
Internet www.MMF.de
Note: The latest version of this manual can be found at http://www.mmf.de/prod-
uct_literature.htm
Specification subject to change.
© 2014 Manfred Weber Metra Mess- und Frequenztechni in Radebeul e.K.
Full or partial reproduction subject to prior written approval.
Nov/ 22 #194

Contents
1. Purpose.................................................................................................................2
2. The Device at a Glance.........................................................................................2
3. Fundamentals of Human Vibration Measurement................................................3
3.1. Introduction...................................................................................................3
3.2. EU Occupational Health Directive 2002/44/EC............................................4
4. Human Vibration Measurement with the VM31...................................................7
4.1. Batteries.........................................................................................................7
4.2. Switching on and Connecting the Sensor......................................................8
4.3. Hand-Arm Measurement with the VM31......................................................9
4.3.1. Measuring Points for Hand-Arm Vibration............................................9
4.3.2. VM31 Settings.....................................................................................10
4.4. Whole-Body Measurement with the VM31.................................................12
4.4.1. Measuring Points for Whole-Body Vibration......................................12
4.4.2. VM31 Settings.....................................................................................14
4.4.2.1. Whole-Body Measurement with RMS Values..............................14
4.4.2.2. Whole-Body Vibration Measurement with VDV Values..............18
4.4.2.3. Seat Effective Amplitude Transmissibility (SEAT)......................19
5. General Vibration Measurement.........................................................................19
6. Data Logger........................................................................................................22
7. Frequency Analysis............................................................................................23
8. Data Memory......................................................................................................24
8.1. Measurement Data Memory........................................................................24
8.2. Logger Data Memory..................................................................................24
8.3. FFT Data Memory.......................................................................................25
9. Keypad Loc ......................................................................................................25
10. Device Settings.................................................................................................25
10.1. Sensor Calibration.....................................................................................25
10.2. Time and Date...........................................................................................25
10.3. Shut-off Timer...........................................................................................26
10.4. Battery Type..............................................................................................26
10.5. Display Brightness....................................................................................26
10.6. Menu Language.........................................................................................26
10.7. Default Settings.........................................................................................27
11. Reset Key..........................................................................................................27
12. Connection to a PC...........................................................................................27
13. Data Transfer to a PC........................................................................................28
13.1. Opening the Excel File vm31.xlsm...........................................................28
13.2. Data Import to Excel.................................................................................29
13.3. Calculation of Vibration Exposure A(8) and VDV(8)...............................29
13.4. FFT Data Import to Excel.........................................................................30
14. Firmware Update..............................................................................................31
15. Calibration........................................................................................................33
16. Technical Data..................................................................................................34
Appendix: Warranty
Declaration of CE Conformity
1

Thank you for choosing a Metra Vibration Measurement device!
1. Purpose
The VM31 has been developed, particularly, for the measurement and analysis of
human vibration. Other fields of application include machine condition monitoring,
building vibration measurement and quality control.
In combination with a triaxial 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 mea-
surements (seat effective acceleration transmissibility).
The VM31 meets the requirements for human vibration meters in compliance with
ISO 8041. In the development of the VM31 value was placed on simple operation
and compact design.
In addition to its application as human vibration meter the VM31 can also measure
machine vibration according to ISO 10816-1/2/3/5/6/7. Measuring ranges for accel-
eration, velocity and displacement are available.
2. The Devi e at a Glan e
2
Figure 1: Controls, connectors and display

3. Fundamentals of Human Vibration Measurement
3.1. Introdu tion
Vibrations affecting the human body are called human vibration. The main purpose
of measuring human vibration is the prevention of health ris s 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 buttoc s, the bac and the feet of a sit-
ting person, the feet of a standing person or the bac and the head of a recumbent
person. Such vibrations may cause bac ache or damage to the spinal column.
Both types of human vibration measurement are described in international standards:
•ISO 5349 - Measurement and evaluation of human exposure to hand-transmitted
vibration
•ISO TR 18570 – Measurement and evaluation of human exposure to hand-trans-
mitted vibration – Supplementary method for assessing ris of vascular disorders
•ISO 2631 - Evaluation of human exposure to whole-body vibration
(also ASA/ANSI S3.18)
•ISO 8041 - Human response to vibration. Measuring Instrumentation
•ISO 8662 - Hand-held portable power tools - Measurement of vibrations at the
handle
•ISO 20283-5 - Guidelines for the measurement, reporting and evaluation of vi-
bration with regard to habitability on passenger and merchant ships
•ISO 10056 - Measurement and analysis of whole-body vibration to which pas-
sengers and crew are exposed in railway vehicles
•ISO 10326 - Laboratory method for evaluating vehicle seat vibration
•ISO 28927 - Hand-held portable power tools - Test methods for evaluation of vi-
bration emission
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 re -
gard to wor ers protection.
3

3.2. EU O upational Health Dire tive 2002/44/EC
The following text is an abstract of Directive 2002/44/EC of the European Parlia -
ment and of the Council dated June 25, 2002. The complete text can be downloaded
from http://eur-lex.europa.eu/
The directive specifies minimum requirements for the protection of wor ers from
the ris s arising from vibrations. Manufacturers of machines and employers should
ma e adjustments regarding ris s related to exposure to vibration.
The directive lays down the following limit values:
Hand-Arm, RMS Whole-Body, RMS Whole-Body, VDV
Exposure action
value
2.5 m/s² 0.5 m/s² 9.1 m/s1,75
Exposure limit 5 m/s² 1.15 m/s² 21 m/s1,75
Table 1: Limits to EU directive 2002/44/EC
Once the exposure action value is exceeded, the employer shall establish and im-
plement a program of technical and organizational measures intended to reduce to a
minimum exposure to mechanical vibration, ta ing into account in particular:
•Other wor ing methods that require less exposure to mechanical vibration
•Appropriate wor equipment of ergonomic design, producing the least possible
vibration
•Provision of auxiliary equipment that reduces the ris of injuries, such as protec-
tive gloves or special seats
•Appropriate maintenance programs for wor equipment
•Design and layout of wor places
•Adequate information and training to instruct wor ers to use wor equipment
correctly and safely
•Limitation of the duration and intensity of the exposure
•Wor schedules with adequate rest periods
•Provision of clothing to protect wor ers from cold and damp
In any event, wor ers shall not be exposed above the exposure limit value. If this
should be the case, the employer shall ta e immediate action to reduce exposure be-
low the exposure limit value.
The methods used may include sampling, which must be representative of the per -
sonal exposure of a wor er to the mechanical vibration in question.
The assessment of the level of exposure to vibration is based on the calculation of
daily exposure A(8) expressed as equivalent continuous acceleration over an eight-
hour wor period. For the determination of A(8) it is not necessary to measure over
eight hours. It is sufficient to ma e short-term measurements during representative
wor steps. The results are normalized to eight hours. Daily exposure is calculated
as follows:
4

A(8)=awe
√
Te
T0
Equation 1
where
A(8) is the daily exposure
awe is the energy equivalent mean value of the frequency weighted acceleration
during exposure, which means
- For Hand-Arm Vibration the X/Y/Z vector sum of Wh frequency-
weighted RMS values (Equation 2)
aw=
√
awx
2+awy 2+awz 2
Equation 2
- For Whole-Body Vibration the highest of the three RMS values
awx, awy and awz with the following frequency and magnitude weightings:
- X and Y with weighting filter Wd and weighting factor 1.4
- Z with weighting filter W and weighting factor 1.0
Te is the total duration of exposure during one wor day
T0is the reference duration of 8 hours
Daily exposure may consist of several partial exposures with different vibration
magnitudes. This can be the case if there are longer interruptions in the wor
process, if the wor equipment or its way of use is changed. A partial exposure sec-
tion should have a roughly constant magnitude and less than 10 % interruptions. Re-
sulting daily exposure is calculated as follows:
Hand-Arm Vibration:
A(8)=
√
1
T0
∑
i=1
n
awi
2Tei
Equation 3
where
A(8) is the daily exposure
awi is the energy equivalent mean value of the Wh frequency weighted accelera-
tion of partial exposure section i
n is the number of partial exposure sections
Tei is the duration of exposure i
T0is the reference duration of 8 hours
Whole-Body Vibration:
Separate daily exposures need to be calculated for X/Y/Z. The highest value is used
for the evaluation, i.e. compared with the limits of Table 1.
Ax(8)=
√
1
T0
∑
i=1
n
awxi
2Tei
Equation 4
5

Ay(8)=
√
1
T0
∑
i=1
n
awyi
2Tei
Equation 5
Az(8)=
√
1
T0
∑
i=1
n
awzi
2Tei
Equation 6
where
Ax/y/z(8) are the daily exposures of directions X/Y/Z
awx/y/zi are the energy equivalent mean values of the frequency weighted accelerations
in the directions X/Y/Z during partial exposure section i with the following
frequency and magnitude weightings:
- X and Y with weighting filter Wd and weighting factor 1.4
- Z with weighting filter W and weighting factor 1.0
n is the number of partial exposure sections
Tei is the duration of exposure i
T0is the reference duration of 8 hours
The calculations shown above are based on RMS values. An alternative method
uses fourth-power mean values called Vibration Dose Value (VDV) with the mea-
suring unit m/s1,75. Table 1 also includes VDV based limit values.
VDV based daily exposure VDV(8) is calculated:
VDV (8)=VDV⋅4
√
Texp
Tmeas
Equation 7
where
VDV(8) is the daily exposure value
VDV is the frequency-weighted vibration dose value
Texp is the duration of exposure
Tmeas is the duration of VDV measurement
Daily exposure may consist again of several partial exposure sections. Separate
daily exposure values are to be calculated for X/Y/Z. The highest one is compared
with the limits of Table 1 for evaluation.
VDV x(8)= 4
√
∑
i=1
n
VDV xi
4⋅Tiexp
Timeas
Equation 8
VDV y(8)= 4
√
∑
i=1
n
VDV yi
4⋅Tiexp
Timeas
Equation 9
VDV z(8)= 4
√
∑
i=1
n
VDV zi
4⋅Tiexp
Timeas
Equation 10
where
6

VDVX/Y/Z(8) are the daily exposures of directions X/Y/Z
VDVx/y/zi are the frequency-weighted vibration dose values of directions X/Y/Z dur-
ing exposure section i
Tiexp is the duration of exposure section i
Tmeas is the duration of VDV measurement during exposure section i
Model VM31 measures Hand-Arm and Whole-Body vibration, the latter as RMS or
VDV values. For the calculation of daily exposure an Excel sheet with a data import
function is provided.
4. Human Vibration Measurement with the VM31
4.1. Batteries
The VM31 is powered from three standard al aline bat-
teries size AAA (LR03). Alternatively rechargeable
NiMH batteries of type HR03 can be inserted. Precise
operation is guaranteed until the batteries are almost
completely discharged.
Please note that date and time need to be adjusted after
replacing the batteries. All other settings, including
saved measurements, remain stored after removing the
batteries.
To insert the batteries, remove the two screws from the
bac cover of the device and open the battery compart-
ment (Figure 2). When inserting the batteries, please en-
sure that their polarity is correct, (see the engraved
mar ings inside the compartment).
Important:
•Always use three batteries of the same type and same date of manufacture.
•Remove old batteries from the device, and ta e out the batteries if the device will
not be used for a long period of time. Otherwise lea ing battery acid may cause
severe damage to the device.
Please use your local collection point to dispose of batteries.
Batteries do not belong to the household waste.
A battery indicator can be found in the upper left corner of the display. A green
filled battery symbol indicates a fully charged battery. When the symbol becomes
red only a small portion of power remains and the unit will switch-off soon. Please
also read section 10.4..
If the VM31 is connected to a USB interface, it will be powered via USB to save the
batteries. In this case “Extern” is shown instead of the battery symbol.
7
Figure 2: Batteries

4.2. Swit hing on and Conne ting the Sensor
Switch on the VM31 by pressing the ON/OFF ey. The
unit can be switched off again by pressing and holding
the ON/OFF ey for one second.
If the sensor has not yet been connected, plug the sensor
cable into the right connector. The VM31 will start
TEDS1 detection each time it is switched on or a sensor is
connected. It supports IEEE 1451.4 TEDS template no.
25 (with or without transfer function). The sensitivities of
X/Y/Z and channel A are displayed for some seconds
(Figure 3). For each channel also the user text of TEDS
(ID) is displayed.
The sensors KS963B100-S and KS963B10 supplied by Metra feature TEDS.
Should a connected sensor not have TEDS or an incompatible TEDS version, the
VM31 will open a menu for entering the sensitivities manually (see section 10.1.).
The sensitivities entered remain stored as long as the sensor is connected, even if the
batteries are removed.
The warning “SENSOR!” indicates a missing or defective sensor or a bro en sensor
cable. Sensor condition is detected by means of the bias voltage at the sensor out -
put:
< 0.7 V: short circuit
0,7 – 14 V: normal
>14 V: open, e.g. bro en cable
Please note that settling time after connecting a sensor is
about 1 minute.
The VM31 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.
1 TEDS = Transducer Electronic Data Sheet
8
Figure 3:
TEDS detection
Figure 4: Seat pad accelerometer KS963B100-S
Figure 5:
Hand-Arm accelerometer KS963B10
Figure 6:
Sensor soc et
(view from outside)