Hazmat vs Placarding??

men in hazmat suits

First of all, let’s identify how the Department of Transportation (DOT) defines Hazardous Materials or Hazmat.

.. DOT defines a hazardous material as any item or chemical which, when being transported or moved in commerce, is a risk to public safety or the environment, and is regulated as such under its Pipeline and Hazardous Materials Safety Administration regulations (49 CFR 100-199)..

Any item or chemical that is a risk to public safety or environment pretty well sums up what hazmat could potentially be. In the world of D.O.T., they break down any item or chemical into 9 different categories or hazard classes.

  1. Explosives
  2. Gases
  3. Flammable and Combustible Liquids
  4. Flammable Solids
  5. Oxidizing Substances, Organic Peroxides
  6. Toxic Substances and infectious Substances
  7. Radioactive Materials
  8. Corrosives
  9. Miscellaneous Hazardous Materials

After looking at this list of hazard classes, questions can potentially arise about what types of materials that would fit some of these categories. Some common questions that come from various transporters are related to Flammable Solids, and items that could be considered under the Miscellaneous Hazardous Materials. An example of flammable solids would be defined by DOT as follows:

  1. Solids which may cause a fire through friction, such as matches.
  2. Pyrophoric (literally, “fire-loving”) materials, those that can ignite with no external ignition source within five minutes after coming in contact with air.
  3. Self-heating materials, those that exhibit spontaneous ignition or heat themselves to a temperature of 200 deg.C (392 deg.F) during a 24-hour test period. (This behavior is called spontaneous combustion)
  4. Dangerous when wet materials, those that react with water to become spontaneously flammable or to give off flammable gas or toxic gas at a rate greater than 1 liter per kilogram of the material, per hour.

One flammable solid that always comes to our minds is magnesium which if in the right conditions like getting wet with water, can cause all kinds of fireworks.

As far as the Miscellaneous Hazardous Materials found in class 9, DOT defines those as follows:

Class 9 hazardous materials are miscellaneous hazardous materials. That is, they are materials that present a hazard during transportation, but they do not meet the definition of any other hazard class.

Class 9 hazmat includes:

  • Materials transported by air that could cause extreme annoyance to a flight crew member to the extent that it prevents the crew from performing its duties;
  • Hazardous wastes;
  • Hazardous substances;
  • Marine pollutants; and
  • Materials that meet the definition in the hazardous materials regulations (HMRs) for an elevated temperature material.

When transporting various hazardous waste streams from their generators to the final disposal, many times class 9 was used for items such as Ethylene Glycol (spent automotive anti-freeze).

Now that we completely dumped a ton of information regarding what a hazardous material is, another frequently asked question that we receive is what all hazardous materials or waste needs to have placards, how often should we use them, and how many do I need to put on my loads. DOT offers some basic regulations regarding placarding.

When the aggregate gross weight of all hazardous materials in non-bulk packages covered in Table 2 is less than 454 kg (1,001 lbs), no placard is required on a transport vehicle or freight container when transported by highway or rail [§172.504(c)].

Non-bulk packages are considered to be portable containers like drums, totes, boxes, crates etc. A bulk package would be complete tankers, rail tanks or vessels. General rule for differences between the two; bulk and non-bulk, bulk containers are built into the unit transporting them, whereas non-bulk containers can be moved from unit to unit by hand, lift trucks or cranes.


(1) Tank Cars, Cargo Tanks, Portable Tanks, and other Bulk Packaging; (2) Transport vehicles or freight containers containing 4,000 kg (8,820 lbs) in non-bulk packages of only a single hazardous material having the same proper shipping name and identification number loaded at one facility and transport vehicle contains no other material, hazardous or otherwise; and (3) transport vehicles or freight containers containing 1,000 kg (2,205 lbs) of non-bulk packages of materials poisonous by inhalation in Hazard Zone A or B. See §§172.301(a)(3), 172.313(c), 172.326, 172.328,172.330, and 172.331.

To clarify, anything meeting this large shipment requirement not only requires the placard but also an Identification number as shown below.

Like this example if I was transporting drums of hydrochloric acid I would just need to placard my load and label each container with the Corrosive Class 8 Placard and label. But, If I was transporting a major cargo tank full of hydrochloric acid, I would need to use the Corrosive Class 8 placard and label with 1789 ID number.

When placarding a transport truck, bus, trailer, tanker, and placards need to be visible on all four sides of the unit and placards need to be at least 9.84”on all sides. Sticker labels need to be at least 3.9” on all sides.

Again, we just touched on just a few basic items regarding hazmat and placarding but we are excited to give any guidance regarding placarding or hazardous materials. Please feel free to contact us to help make your life easier.

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