Silica Comparison: Wet vs. Dry vs. Vapour Blasting

How well does your machine protect you from respirable silica?

The Test

Permissible Exposure Limit (PEL) Test Parameters

 Media: Medium recycled crushed glass

 Blast Hose: 15 m (50 ft) x 38.1 mm (1.25 in) ID

 Nozzle: #8 High Performance

 Compressor: Doosan 425 CFM

 Substrate: 1.22 m x 1.22 m (4 ft x 4 ft) Concrete Slab

 Blasting Time per Test: 25 – 28 minutes

Graco retained a third party to perform an Industrial Hygiene Survey in order to evaluate potential exposures to respirable airborne dust and respirable silica during three separate blasting operations. Blasting parameters were kept constant for the three scenarios with the exception of the blasting equipment used and the usage of water. Blasting was performed on a 1.22 m x 1.22 m (4 ft x 4 ft) slab of concrete using medium crushed glass abrasive.

Respirable silica dust based on blasting technology

How long can you blast before hitting OSHA’s Respirable Silica Limit?

Silica dust blast time comparison

The result:

Occupational exposures to airborne contaminants are evaluated by comparing them to Permissible Exposure Limits (PELs) and Short-Term Exposure Limits (STELs) established by OSHA. PELs are time-weighted average (TWA) concentrations for a normal 8-hour workday or a 40-hour work week. STELs are 15-minute TWA concentrations that shall not be exceeded any time during the workday.

Third-Party Testing Reports

WATCH: Silica PEL Comparison


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