HAND-ARM VIBRATION SYNDROME |
Performance
Requirements of an
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| NIOSH Requirements for Antivibration Gloves |
| NIOSH(1) publication 89-106 on Occupational Exposure
to Hand-Arm Vibration states that strategies for reducing hand-arm vibration in the
U.S. shall be supplemented by the "use of antivibration clothing, mittens, gloves,
and equipment." The NIOSH publication further states that the vibration-damping
material in an antivibration glove must:
• "provide adequate damping with minimal thickness so that the dexterity required for safe and efficient tool operation will not be reduced, and • provide adequate damping characteristics over the vibration frequency spectrum associated with HAVS." (1) U.S. National Institute for Occupational Safety and Health |
| ISO/ANSI Requirements for Antivibration Gloves |
| ISO(2) Standard 10819
and ANSI(3) S3.40/2002 specifies the test procedures that
must be used to measure the vibration transmissibility of gloves. The vibration transmissibility of a glove per ISO Standard 10819 is the
ratio of the vibration amplitude directed into the palm of the hand inside of a glove
divided by the vibration amplitude directed into the palm on the outside surface of the
glove. The vibration transmissibility of
a glove is a measure of the attenuation of vibration into the hand and arm by means of a
resilient or vibration- damping material placed in the glove. The lower the
vibration transmissibility, the more effective a glove is in reducing vibration energy
into the hand and arm.
Figure 1 - Mid and High Frequency Test Spectra per ISO Standard 10819 ISO Standard 10819 specifies the amplitude of vibration transmissibility that must be achieved for a glove to be classified as an antivibration glove. The standard requires the overall vibration transmissibility of a glove to be measured for mid frequencies (frequency range from 16-400 Hz) and for high frequencies (frequency range from 100-1,600 Hz). Figure 1 shows the third octave amplitudes of the vibration spectra for the mid and high frequency test signals, respectively. Vibration first corresponding to the mid frequency test spectra and then to the high frequency test spectra are directed into the hand by means of a 40 mm (1.5 in.) diameter handle attached to a vibration shaker. Sets of two measurements on each of three test subjects for a total of six measurements are made for each frequency range. Three different gloves, one for each test subject, are used for each series of tests. The six individual transmissibility values for both the mid and high frequency test spectra are averaged to obtained the average transmissibility values. The average mid frequency transmissibility is designated TRM, and the average high frequency transmissibility is designated TRH. For a glove to be classified as an antivibration glove: • TRM must be less than 1.0 and TRH must be less than 0.6. • The resilient or vibration-damping material must be placed in the palm and the full finger and thumb stalls of the glove. In Europe, a glove cannot be marketed as an antivibration glove unless it meets the above requirements for ISO Standard 10819. There are no such requirements in the United States. However, a US company should not use a glove that claims to be a vibration-reducing or an antivibration glove to mitigate hand tool vibration problems unless the glove meets the requirements of ISO Standard 10819 for classification as an antivibration glove.(2)International Organization for Standardization |
| Vibration Transmissibility Values |
| Three types of vibration transmissibility values should
be obtained to evaluate the performance of a glove used to reduce hand-arm vibration. They
are: • TRM and TRH values, using the strict test procedures specified by ISO Standard 10819. ISO standard 10819 requires that the overall vibration amplitudes incident on the surface of the glove and at the palm of the hand for the mid and high frequency test spectra be measured with the ISO weighting filter specified by ISO Standard 5349. The attenuation characteristics of this filter are shown in Figure 2. The ISO weighting filter biases the ISO transmissibility of a glove towards the vibration energy present in the region near the lower frequency limit of each test spectra. This tends to under specify the effectiveness of a glove in reducing vibration into the hand and arm.
Figure 2 - ISO Hand-Arm and Linear Weighting Filter Characteristics • TRM and TRH values, using the test procedures specified by ISO Standard 10819 with a linear weighting filter (See Figure 2). A linear weighting filter treats all of the frequencies within the mid and high frequency test spectra equally. TRM and TRH values measured with a linear weighting filter give a more accurate indication of the mid and high frequency vibration attenuation characteristics of a glove. • Third octave transmissibility values for the third octave frequencies from 16-1,600 Hz per the ISO Standard 10819 test procedures. These values specify the vibration attenuation characteristics of a glove over the test frequency range. These are the most descriptive of the three sets of transmissibility values that have been presented. |
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