Derating How Much Why

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Derating? How Much? Why?
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Copies of the presentation

• mdenton_at_mmm.com

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Why Derate?
Occupational Health Environmental Safety
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Derating

• Most enforcement bodies recommend derating
• The derating varies from one to another
• The situation can determine the derating

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Real World Attenuation

• Not everyone achieves the same attenuation
• Some through inability to fit
• Some through lack of attention

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Real World Attenuation

• Often the worst cases are through lack of
  training
• Would you give the pool car keys to someone
  without a driving licence?
• The law requires training for all supplied with
  PPE

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The line in the sand

• There are several noise levels in legislation
• 80 dB(A) First Action Value
• 85 dB(A) Second Action Value
• 87 dB(A) Limit Value

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Too close for comfort

• We cannot exceed 87 dB(A) under any circumstances
• How accurate are our calculations?

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EN 458

• We target 75 - 80 dB(A)
• This is Good
• 70 75 is Adequate, as is 80 85
• 0ver 85 too low, under 70 too high

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EN 458

• I suggest 80 85 too risky
• 75 80 ideal
• 70 75 Acceptable
• Under 70, attenuation too high

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EN 458

• If we go with EN 458 we dont need to derate
• Unless we get to 80 85 under the HPD
• The we should derate to be sure
• But we might as well target 70 80 in the first
  place

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Training and Education

• The moral is-
• Reduce the risk by training and education first
• Dont approach the Limit Value
• Use EN 458 as your guide

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Copy of this presentation

• mdenton_at_mmm.com