#2: Vapor Density
density is defined as the ratio of a product’s vapor to the density of
air. Substances with a vapor density greater than 1 are heavier than air and
tend to accumulate at the low level of enclosed spaces.
| Several products on our list have
heavier densities than gasoline. However, when their risk of vapor ignition
is taken into account, they are not as dangerous, mainly because their flash
points are much higher. Similarly, while propane has a lower flash point than
the other products, its vapor is almost as light as air.
|(Bridge) Finally, we’ll look at flammable
range as a risk factor.