Classifying compressed gases for proper application of Codes (Chlorine and Phosgene)

I have been catching up on my Chlorine posts these last several weeks and some have asked me how I know which chemical goes into which hazard class; specifically, why Chlorine is “only toxic” and not “highly toxic”.  As I said in a few of my previous articles on safely managing Cl2, some of my businesses that had actual “highly toxic” materials went ahead and put Cl2 into that group for “good measure”, some even built their process as “lethal service”.  We were already managing some actual HAZMATs that were by definition “highly toxic” so adding Cl2 to this group was not difficult or expensive.  But for a facility that does not already have materials that have to be managed as “highly toxic”, doing so with Cl2 will require an extra effort and full support from management.  Heck for that matter, by code, even Phosgene is only “toxic” but in the two businesses I worked for that had Phosgene, one managed it as a “highly toxic” and “lethal service”.  Here is a nice cheat sheet of what the IFC considers “toxic” and “highly toxic” compressed gas for the proper application of the code:

First thing, compressed gases by definition are material, or a mixture of materials, that:

1. are a gas at 68°F (20°C) or less at 14.7 pounds per square inch atmosphere (psia) (101 kPa) of pressure.
2. have a boiling point of 68°F (20°C) or less at 14.7 psia (101 kPa), which is either liquefied, nonliquefied or in solution, except those gases that have no other health or physical hazard properties and are not considered to be compressed until the pressure in the packaging exceeds 41 psia (282 kPa) at 68°F (20°C).

The states of compressed gases are categorized as follows:

1. Nonliquefied compressed gases are gases, other than those in solution, that are in a packaging under the charged pressure and are entirely gaseous at a temperature of 68°F (20°C).
2. Liquefied compressed gases are gases that, in a packaging under the charged pressure, are partially liquid at a temperature of 68°F (20°C).
3. Compressed gases in solution are nonliquefied gases that are dissolved in a solvent.
4. Compressed gas mixtures consist of a mixture of two or more compressed gases contained in a packaging, the hazard properties of which are represented by the properties of the mixture as a whole.

Here are the criteria for “Toxic” and “Highly Toxic” by the numbers!  And you just thought you’d never use LC50 and LD50 in your career (LOL)…

Some of the more common examples of highly toxic and toxic compressed gases are:

NOTE: this list was compiled using the LC50 for these materials.

*Highly Toxic gases would also be a Category 1 (Acute Toxicity) per OSHA; Category 2’s would be Toxic Gases

Compressed gases that are either toxic or highly toxic must meet the minimum requirements of:

Chapter 50: Hazardous Materials—General Provisions:

• SECTION 5001 GENERAL
• SECTION 5003 GENERAL REQUIREMENTS
• SECTION 5004 STORAGE
• SECTION 5005 USE, DISPENSING, AND HANDLING, and

Chapter 60: Highly Toxic and Toxic Materials

• SECTION 6004 HIGHLY TOXIC AND TOXIC COMPRESSED GASES

and

• Chapter 53: Compressed Gases
• Chapter 54: Corrosive Materials
• Chapter 55: Cryogenic Fluids, and
• Chapter 58: Flammable Gases and Flammable Cryogenic Fluids