City Guilds Model Questions Vol1 2024 Engineering Question 9
Practice objective / multiple choice question 9 from the 2024 City Guilds Model Questions Vol1 Engineering examination.
In a workshop, a grinding machine produces a noise level of 95 dB(A) at the operator's ear. The permissible exposure limit (PEL) for an 8‑hour shift is 85 dB(A). According to the safety table, for every 5 dB increase above the PEL the required attenuation doubles from a baseline of 10 dB at 90 dB. Assuming a 50 % derating is applied to the Noise Reduction Rating (NRR) of earplugs, determine the minimum NRR (in dB) that the earplugs must have to protect the operator. Also state the maximum continuous exposure time allowed when using earplugs with that NRR.
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About This Question
This is City Guilds Model Questions Vol1 2024 Engineering Question 9. It is one of the objective questions from the 2024 City Guilds Model Questions Vol1 Engineering examination.
Difficulty level: Medium .
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