Local Exhaust Ventilation

Local exhaust ventilation is used on hand-held masonry saws in the form of an exhaust hood (or shroud) surrounding the blade. The hood is connected to an industrial vacuum cleaner by a flexible hose. The vacuum cleaner creates suction to capture the dust at its source. For best results, the hood should be near the surface to be cut.

The vacuum cleaner should have the following features:

• A sufficient flow rate, to capture the dust and pull it to the vacuum source (an air flow rate of 70 cubic feet per minute (cfm) is required to achieve effective dust control).
• A HEPA filter, to reduce the chances of releasing silica dust from the vacuum into the worksite.
• A pre-filter or cyclone that will increase the length of service of the HEPA filter.
• A filter replacement indicator, such as a pressure gauge (if the vacuum cleaner does not have a pressure gauge, workers should monitor the air flow by checking to see if a dust plume is escaping from around the shroud).
• The ability to clean and replace filters and collection bowls or bags without exposing the operators to dust
• A motor that draws at least 10 amps
• A 2-inch diameter hose with a smooth interior and a length of no more than 15 feet to provide adequate air flow for capturing and transporting dust (the hose should be mostly straight, and should have as few elbows or turns as possible).

To learn more about Construction Silica visit our Construction Silica Safety Online Training web page.