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entire prefilter section. Specify a filter material that is not damaged by the styrene and
acetone vapor produced in FRP facilities.
Industrial Vacuum System. Install a vacuum system; see Figure 5-6, to
exhaust fibers, dry resin and dust from LVHV hand tools when they are used. The
vacuum system also allows workers to conduct shop cleanup and to decontaminate
their protective outerwear. ACGIH IV Manual, Chapter 10, gives design details and
illustrates power tools using LVHV vacuum systems. The large size and high terminal
velocity of the particulates produced by the hand tools requires a high velocity vacuum
take-off hood for each tool. Generally, design the takeoff hood into the tool's safety
Figure 5-6. Exhaust system schematic.
Vacuum System Design. Design the vacuum system in accordance with
the following criteria:
a. Ensure each take-off hood produces the proper capture velocity. This
is the most important consideration in designing the vacuum system.
Design the hood to capture contaminants as close as possible to the point
of generation. Design vacuum systems to capture contaminants within
12.7 mm (1/2 inch) of the source.
b. Design the capture air-stream to have a velocity of two to three times
the generation velocity for particles of 20 to 30 micrometers (20 to 30
microns.) Design for an additional velocity of:
1. Four to five times the generation velocity to pull the particles up
through 300 U.S. standard mesh, or