# Glossary of Terms for Hand Arm Vibration

## Explaining the technical terms found in Hand Arm Vibration

Keep your vibration assessments easy with this glossary of terms explaining the technical terms found in Hand Arm Vibration is plain and simple English.

Read on to learn the technical terms found in Hand Arm Vibration, or read our article: The Definitive Guide to Managing Hand Arm Vibration in the Workplace.

## Aeq Acceleration Equivalent Value

Once you have measured a tool, the result will be given as an Aeq. The term Aeq simply stands for the Acceleration equivalent value. Acceleration is the vibration parameter used in human vibration measurements and is measured in metres per second squared (m/s2). The ‘equivalent’ part of the term simply means the average vibration level.

### Techie bit

Aeq is a single number that represents the equivalent energy of a varying source. In other words you get the same amount of energy from the varying vibration level as you would from the continuous, equivalent value. You can expect results to range from around 0.5m/s2 to about 20m/s2 although this is only a rough guide and we have measured equipment as high as 30m/s2. Anything above 25m/s2 would be considered to be extremely high.

## M/s2 Meters per Second Squared

Meters per second squared, or M/s2, is the standardised measurement unit of acceleration or vector magnitude. Within vibration monitoring M/s2 is defined either as an average over time or as an instantaneous reading.

## RMS Root Mean Squared Amplitude

Root Mean Square Amplitude, or RMS, is the square root of the average of the squared values of the vibration waveform.

RMS takes into account the time history of the waveform, giving an amplitude value which directly relates to the energy content. RMS is therefore considered the most relevant measure of amplitude in order to assess levels of damage.

## EAV Exposure Action Value

The Exposure Action Value is a daily amount of exposure which employers are required to take action to control exposure to eliminate risk or reduce exposure to as low as is reasonably practicable.  Set and enforced by The Control of Vibration at Work Regulations 2005, the EAV level is set at 2.5 m/s² average over 8 hours (A(8)).

## ELV Exposure Limit Value

The Exposure Limit Value (ELV) is the maximum amount of vibration an employee may be exposed to on any single day. The Exposure Limit Value is the level of exposure where employers must take immediate action to reduce their exposure below the limit value. The EAV level is set at 5 m/s2 average over 8 hours (A(8)).

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