Owner's manual

Page 73 of 197
12. Switch the photometer sampling valve to upstream, and establish this aerosol
concentration as 100%, per the photometer manufacturer’s instructions.
13. Establish the 0% concentration per the photometer maker’s instructions.
14. The Logic is now ready for the HEPA Filter Leak Test. Set the photometer
sampling valve to “DOWNSTREAM”. Ensure there is a proper vacuum at the
sampling port of the pistol.
12. Scan the downstream side of the HEPA filter by passing the sampling nozzle of
the gun in slightly overlapping strokes over the entire surface of both of the
filters, with the sampling port not more than 1 inch from the surface of the filter
media. Scan the entire periphery of the filters and the gaskets between the filter
frame and the Logic frame. Scanning shall be done at a traverse rate of not more
than 2 inches per second.
Note: Operation of the photometer may become erratic when testing the front edge of
the supply filter frame, due to aspiration of room air into the front of the work area. This
problem can be minimized or eliminated by placing the edge of a sheet of rigid plastic or
metal at the edge of the filter gasket when scanning this area, as shown in Figure 5-11.
Figure 5-11
Acceptance
Aerosol penetration shall not exceed 0.01%.
Reassemble the unit by compressing the exhaust filter cover while installing its tabs
back into the exhaust filter bracket slots. Reinstall the diffuser, ensuring that the holes in
the back of the diffuser frame engage the posts on the rear wall of the work area, as
shown in Figure 5-12. Replace the access tube, and the work surface.
Figure 5-12
Diffuser pins engaging the holes in the rear of
the diffuser.