CertiGuide to A+ (A+ 4 Real)  9  Chapter 12: Material Safety: a Personal and Technical Report on Hazardous Material Handling       9  Reading and Understanding MSDSs

Understanding Parts Per Million (PPM) 1 Section Four - Fire/Explosion Data

In this section, we find information about the physical properties of the chemical. As you can imagine, boring stuff like the look, smell, weight and what physical reactions you can expect it to do under certain conditions. Much of this information is also needed for the calculation of approximate concentration levels and dispersal patterns.

Let us start with Appearance, Color and Odor. Essentially, this allows us to recognize and/or identify the substance. This information is too often used in trying to identify what is actually in a container that is improperly labeled (note, no label is almost the worst kind of an improperly labeled container). Now, you would not transfer a hazardous substance into a different container without labeling it, would you?

The products pH tells us if a product is acidic or alkaline. The Boiling Point and Melting Point gives the temperature that the product will turn into gas and liquid, the percent volatile tells how much of the product will evaporate. Volatile Organic Compounds (VOC) gives the amount of organic compounds that will evaporate. Evaporation Rate, how fast it will evaporate. The vapor pressure of a liquid is the pressure exerted by its vapor when the liquid and vapor are in dynamic equilibrium in a closed container. Vapor density and Specific Gravity indicates whether the product is heavier or lighter than air and water.

Many of these values will compare itself to a constant (that is usually stated as equaling 1) to give a relative indication of the meaning of the value. Lets take the vapor density of Tcat’s Unreal Kleen as an example, 1.75 – 2.5 (air = 1), with the air being stated as the constant we know that Tcat’s Unreal Kleen is 1¾ to 2 ½ times heavier than air. Methane on the, other hand, that has a value of 0.547 when compared to the air, is almost one half lighter than air. So, carrying on, that means that Tcat’s Unreal Kleen evaporates 7 ½ times faster than n-Butyl Acetate (and we all know how fast n-Butyl Acetate evaporates, don’t we).

Had enough yet safety terms and acronyms yet? We have not even scratched the surface of terms and acronyms in the world of safety. However, just in case that you may feel the need for more, you can check out the MSDS Hyper Glossary web site¹⁵⁴. Look on the bright side; at least you do not have to memorize these for a test like the ones that Tcat has been shoveling at you. Well, okay, you do need to know what the acronym “MSDS” means for the A+ test. Just as a refresher in case you have already forgotten, „Material Safety Data Sheet“.

Understanding Parts Per Million (PPM) 1 Section Four - Fire/Explosion Data