Hazardous Materials: Segregation
9 questions in the bank cover this topic. Everything below is drawn from the sources those questions cite.
Sources: 49 CFR 177.848
What you need to know
177.848(e)(2) makes X an absolute bar on carrying the two together.
A blank space or an absent class means no restriction, so the table only speaks where it has to. Not in the same vehicle or storage facility.
The letter “X” in the table indicates that these materials may not be loaded, transported, or stored together in the same transport vehicle or storage facility during the course of transportation.
49 CFR 177.848
177.848(e)(1) reads a blank, or the absence of a class, as no restriction.
You do not need permission for combinations the table does not address.
The absence of any hazard class or division or a blank space in the table indicates that no restrictions apply.
49 CFR 177.848
177.848(c) names cyanides and acids specifically, because the reaction produces hydrogen cyanide gas.
This is a named prohibition in the text, not merely a table entry.
cyanides, cyanide mixtures or solutions may not be stored, loaded and transported with acids if a mixture of the materials would generate hydrogen cyanide
49 CFR 177.848
177.848(c) bars Division 4.2, spontaneously combustible materials, with Class 8 liquids.
A corrosive leak reaching a material that ignites on its own is a fire with no ignition source needed.
Division 4.2 materials may not be stored, loaded and transported with Class 8 liquids
49 CFR 177.848
177.848(c) lists all of them.
Hazard Zone A is the most acutely toxic-by-inhalation category, so it is kept away from anything that could burn, react or breach its packaging.
Division 6.1 Packing Group I, Hazard Zone A material may not be stored, loaded and transported with Class 3 material, Class 8 liquids, and Division 4.1, 4.2, 4.3, 5.1 or 5.2 materials
49 CFR 177.848
177.848(a) covers packages requiring a label or placard under Part 172, compartments in a multi-compartmented cargo tank subject to 173.33, and portable tanks loaded in a vehicle or freight container.
Certain cargo tank compartments and portable tanks are covered as well. Certain cargo tank compartments and portable tanks are included too.
In packages that must be labeled or placarded in accordance with part 172 of this subchapter
49 CFR 177.848
177.848(c) calls out cyanides and acids before it reaches the table, because the product of that mixture is hydrogen cyanide.
The same paragraph also separates Division 4.2 from Class 8 liquids.
cyanides, cyanide mixtures or solutions may not be stored, loaded and transported with acids if a mixture of the materials would generate hydrogen cyanide
49 CFR 177.848
O is the conditional one.
The condition is about what happens if a package leaks, not about how far apart you stack them.
The letter “O” in the table indicates that these materials may not be loaded, transported, or stored together in the same transport vehicle or storage facility during the course of transportation unless separated in a manner that, in the event of leakage from packages under conditions normally incident to transportation, commingling of hazardous materials would not occur.
49 CFR 177.848
This one survives whatever separation method you use, which is why it is written as an exception to the O rule rather than inside it.
Class 8 (corrosive) liquids may not be loaded above or adjacent to Class 4 (flammable) or Class 5 (oxidizing) materials
49 CFR 177.848
Check yourself
- You find an X in the segregation table. What does it tell you?
- You find a blank space in the segregation table. What does it tell you?
- What combination does the rule prohibit outright because of what the mixture would produce?
- Which pairing does the rule prohibit alongside the cyanide and acid rule?
- Division 6.1 Packing Group I Hazard Zone A material may not travel with which materials?
- What two kinds of package must be labeled or placarded?
- Which pairing does the rule name outright, ahead of the table?
- You find an O in the segregation table. What does it allow?
- What may never sit above or beside Class 4 or Class 5 materials?
Answers are in the practice test for this topic.