☰

CorbarView

HAV calculator

You can open the calculator here: HAV calculator ...

... and this is the geeky part, where I explain the underlying maths:

Daily exposure

The basis for the calculator is the equation (from ISO 5349):

A(8) = a_hv SQRT (T/T₀)

where:

a_hv is the h-weighted acceleration total value (m/s²);

T is the total daily exposure time;

T₀ is the reference exposure time of 8 hours (28800 seconds).

Exposure Points

To get exposure points values, the HSE system is based on 100 points being the equivalent of A(8) = 2.5 m/s². This is the Exposure Action Value (EAV) defined in the Control of Vibration at Work Regulations 2005.

The equation for the Points Exposure P_E value is then:

P_E = 100 . (a_hv/EAV)² . (T/T₀)

Adding exposures

To add daily exposure from difference machines or processes, the individual partial vibration exposures cannot be simply added together, daily exposure is given by:

A(8) = SQRT(A₁(8)²) + A₂(8)²) + A₃(8)²) + ...)

The advantage of the exposure points system is that partial exposure points can be easily added, so daily exposure points is given by:

P_E = P_E,1 + P_E,2 + P_E,3 + ...

If necessary, conversion from points to daily exposure in dB(A) is given by:

A(8) = EAV . SQRT(P_E/100)

HAV Lookup