Clarke Contractor CROS2 Gebruiks- en onderhoudsinstructies - Pagina 11
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VIBRATION EMISSIONS
Employers are advised to refer to the HSE publication "Guide for Employers".
All hand held power tools vibrate to some extent, and this vibration is transmitted to the operator via
the handle, or hand used to steady the tool. Vibration from about 2 to 1500 hertz is potentially
damaging and is most hazardous in the range from about 5 to 20 hertz.
Operators who are regularly exposed to vibration may suffer from Hand Arm Vibration Syndrome
(HAVS), which includes 'dead hand', 'dead finger', and 'white finger'. These are painful conditions and
are widespread in industries where vibrating tools are used.
The health risk depends upon the vibration level and the length of time of exposure to it......in effect, a
daily vibration dose.
Tools are tested using specialised equipment, to approximate the vibration level generated under
normal, acceptable operating conditions for the tool in question. For example, a grinder used at 45°
on mild steel plate, or a sander on softwood in a horizontal plane etc.
These tests produce a value' a' , expressed in metres per second per second, which represents the
average vibration level of all tests taken, in three axes where necessary. This value appears in the
panel below.
' a ' values in excess of 2.5 m/s
a vibration value of 2.8 m/s
2
value of 11.2 m/s
2
may be used for ½ hour per day only.
The graph shows the vibration value against the maximum time the respective tool may be used, per
day.
It should be noted that if a tool is used under
abnormal, or unusual conditions, then the vibration
level could possibly increase significantly. Users must
always take this into account and make their own
risk assessment, using the graph above as a
reference.
Some tools with a high vibration value, such as
impact wrenches, are generally used for a few
seconds at a time, therefore the cumulative time
may only be in the order of a few minutes per day.
Nevertheless, the cumulative effect, particularly
when added to that of other hand held power tools
that may be used, must always be taken into
account when the total daily dose rate is
determined.
Declared vibration emission value in accordance with EN12096
Measured vibration emission value - a:
Values determined according to EN28622-1
HAND-ARM VIBRATION
2
are considered hazardous when used for prolonged periods. A tool with
may be used for up to 8 hours (cumulative) per day, whereas a tool with a
11
4.46m/s
2