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TDG: Labels, placards and UN numbers

Dangerous goods marks: labels on small containers, placards and UN numbers on large ones, sizes and orientation, the DANGER placard, the 500 kg placarding exemption and when marks must be removed.

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Labels, placards and UN numbers · Question 1Score 0/0

What is the normal minimum side length of a label on a package?

Study reference: TDG Act and Regulations (current to 2026-09-30), Ch. 5 Dangerous goods marks — Part 4, ss. 4.1–4.16.1

All 16 questions in this test

Every question and its answer choices. The correct answers and explanations appear when you take the test above.

  1. What is the normal minimum side length of a label on a package?

    1. 25 mm
    2. 50 mm
    3. 250 mm
    4. 100 mm

  2. When may a DANGER placard replace the class placards on a trailer?

    1. When it carries mixed goods needing different placards, all in small containers
    2. When it carries goods that need an approved ERAP and a subsidiary placard
    3. When it carries Class 1 explosives that are packed in small containers only
    4. When it carries one class of goods over 1 000 kg from a single consignor in bulk

  3. A labelled jerrycan of a flammable liquid is shipped. What must appear next to the primary class label?

    1. The name of the receiving customer
    2. The consignor's ERAP reference number
    3. The date the jerrycan was filled
    4. The shipping name and the UN number

  4. For which goods is the DANGER placard never allowed?

    1. Class 8 corrosives in small drums
    2. Goods that require an approved ERAP
    3. Class 3 liquids in small containers
    4. Class 9 goods mixed with Class 3

  5. A van carries 400 kg gross of Class 8 corrosives that do not need an ERAP. Are placards required on the van?

    1. Yes, any amount of Class 8 needs placards on all four sides
    2. No, loads of 500 kg gross or less are exempt from placards
    3. No, because Class 8 never needs placards on a road vehicle
    4. Yes, unless the driver holds a valid TDG certificate

  6. Who must supply the placards for goods loaded into a large means of containment?

    1. The consignor, unless they are already displayed
    2. Transport Canada, through an inspector
    3. The consignee, after the goods are delivered
    4. CANUTEC, on request by phone

  7. Which practice breaks the rule on misleading dangerous goods marks?

    1. Covering an old placard with durable, weather-resistant material
    2. Removing labels from a drum that has been cleaned and purged
    3. Displaying a Class 3 placard on a truck carrying no dangerous goods
    4. Displaying the correct class placard on each side and on each end of the trailer

  8. Which load still needs placards even though it weighs under 500 kg gross?

    1. A corrosive liquid in Class 8
    2. A toxic gas in Class 2.3
    3. A Class 9 lithium battery load
    4. A flammable liquid in Class 3

  9. What is the minimum side length of a standard placard?

    1. 150 mm
    2. 100 mm
    3. 400 mm
    4. 250 mm

  10. How must labels and placards be displayed?

    1. As a square set on one point, like a diamond
    2. As a rectangle with the long side horizontal
    3. As a triangle pointing upward
    4. As a circle centred on the side of the container

  11. What is the main difference between a label and a placard?

    1. Labels are for road transport; placards are for rail only
    2. Labels are optional; placards are required by law
    3. Labels show the UN number; placards never show it
    4. Labels go on small containers; placards go on large ones

  12. A highway tank carries a liquid in direct contact with the tank. What must be displayed besides the primary class placard?

    1. The driver's TDG certificate
    2. The ERAP reference number
    3. The UN number of the liquid
    4. The consignor's 24-hour number

  13. How high must the UN number digits be when displayed on a large means of containment?

    1. At least 12 mm
    2. At least 6 mm
    3. At least 65 mm
    4. At least 25 mm

  14. A small container holds goods with a primary class and one subsidiary class. How many class labels does it need?

    1. Two: one for the primary class and one for the subsidiary
    2. None, if the outer box is marked LIMITED
    3. One: the primary class label covers both hazards on the package
    4. Three: the two classes plus a DANGER label

  15. Where must the primary class placard appear on a loaded tank trailer?

    1. On the front only
    2. On each side and each end
    3. On the rear only
    4. On the left side and the rear

  16. A carrier delivers its last drum of dangerous goods, and the truck is now empty. What must it do with the placards?

    1. Turn them upside down to show the truck is empty
    2. Leave them on until the next loaded trip
    3. Keep them on as a general warning to drivers
    4. Cover or remove them, since they no longer apply

Labels, placards and UN numbers: key rules to remember

Our summary of what the official handbook says on this topic, in our own words. Read it before or after the practice questions above, then check the original chapter. Read the official chapter ↗

General requirements (ss. 4.1–4.6)

  • The current Regulations call labels, placards, UN numbers and the other required marks "dangerous goods marks" (Part 4); the Act's broader term "safety marks" covers dangerous goods marks plus compliance marks.
  • No one may import, offer for transport, handle or transport a container of dangerous goods unless the required dangerous goods marks are displayed.
  • A mark must not be displayed if it is misleading about the presence or nature of a danger.
  • A large means of containment must already show the required marks immediately before it is loaded.
  • The consignor displays the marks on small containers and on large containers, and supplies placards to the carrier for large means of containment.
  • The carrier keeps the marks displayed during transport and covers or removes marks that no longer apply.
  • Marks must be visible, legible, durable and weather-resistant, on a contrasting background or inside a border.

Labels and placards: size and orientation (ss. 4.7–4.8)

  • Labels and placards are squares displayed on point (diamond orientation).
  • A label is at least 100 mm on each side with a line about 5 mm inside the edge; in some cases it may shrink to 30 mm (for example on a cylinder shoulder).
  • A placard is at least 250 mm on each side with a line about 12.5 mm inside the edge.
  • Labels go on small means of containment; placards go on large means of containment.

Small means of containment (ss. 4.10–4.12)

  • One label for the primary class and one for each subsidiary class go on each small container.
  • The shipping name and the UN number are shown next to the primary class label (the UN number may also go in a white rectangle on the label without the letters UN).
  • UN numbers next to the label are at least 6 mm high on containers over 5 L up to 30 L (cylinders up to 60 L) and at least 12 mm on larger small containers.

Large means of containment (ss. 4.15–4.15.3)

  • The primary class placard is displayed on each side and each end of a large means of containment.
  • The UN number is displayed on a large means of containment when an ERAP is required or when a liquid or gas is in direct contact with the container (not for Class 1).
  • The UN number on a large means of containment is in black digits at least 65 mm high, on an orange panel next to the placard or in a white rectangle on the placard, without the letters UN.
  • On a trailer, the leading-end placard may be displayed on the front of the tractor instead.

DANGER placard (s. 4.16)

  • A DANGER placard may replace other placards on a large means of containment holding two or more kinds of dangerous goods that need different placards, all in small containers.
  • It cannot be used for one class over 1 000 kg from one consignor, goods needing an ERAP, Class 1, Class 2.3, Class 4.3, certain Class 5.2 and 6.1 goods, or Class 7 needing a Category III – Yellow label.

Placarding exemption, 500 kg (s. 4.16.1)

  • A road or railway vehicle does not need placards when the dangerous goods on it have a gross mass of 500 kg or less.
  • The 500 kg placard exemption does not apply to goods needing an ERAP, Class 2.3, Class 4.3, most Class 1, and some Class 5.2, 6.1 and 7 goods.

Removing or changing marks (s. 4.9)

  • When the danger is no longer present (after cleaning, purging or neutralizing), the person who did it must cover or remove the mark.

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