Noise is the risk nobody takes seriously until it is too late. Unlike an accident, hearing loss has no moment at which it happened.
Where it comes from
In blasting, noise has three sources working at the same time:
The air or abrasive jet — at the nozzle, expanding compressed air produces broadband noise. At the wheel, the noise comes from blade rotation and impact.
Abrasive impact on the part — thousands of hits per second, on a metal surface that vibrates like a membrane.
Auxiliary equipment — compressors, extraction fans, conveyors.
The noise inside the helmet
This is the detail most people miss.
An air-fed blasting helmet is not only protection. The air entering the helmet produces noise itself, right next to the operator’s ear.
The reference manual requires the level in the hearing zone, inside the helmet, not to exceed 80 dBA.
What influences that level:
- Helmet material. Non-metallic helmets generally produce less noise.
- The air source. Certain compressors and blowers are considerably quieter.
- The shape of the air inlet openings in the helmet — a well-designed inlet reduces turbulence, and therefore noise.
An operator can wear correct equipment and still be exposed, if the equipment was badly chosen.
What reduces exposure
The enclosure. A cabinet or a closed room separates the source from the operator. It is the most effective measure, because it works without depending on anyone’s discipline.
Automation. If the operator is not next to the jet, they are not exposed.
Equipment selection. At purchase, compare noise levels too, not just throughput and price.
Personal protection. Necessary, but last on the list.
Legal requirements
Permitted exposure levels and employer obligations are set by national occupational health and safety legislation. The figures in this article are technical design references, not legal thresholds.
Related reading
- Blast Cabinet
- Controlling dust in blasting: enclosure, ventilation, protection
- What a blasting safety programme contains
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