NFPA 497 updates the electrical classification (HAZLOC) around PRVs

NFPA 497 has added TWO (2) NEW figures to establish classification areas around Pressure Relief Valve (PRV) vents.  The classification areas of the sources in several figures in Section 5.11 have been removed to eliminate confusion.  This change is significant in two (2) ways:

1. the distance around the PRV went from 3′ to 10′
2. the area is now a Division 2 area, rather than the Div 1 before.

So we used to have a 5′ bubble, which was a Div. 1 area, and now we have a 10′ bubble, which is now a Div 2 area.

Now	Before