UN1824 sodium hydroxide solution table entry.

Where UN1824 sits in the table

UN1824 is the table entry for sodium hydroxide in solution, and this page covers that entry only. The ERG 2024 index lists two names under UN1824: Caustic soda, solution and Sodium hydroxide, solution, both with Guide 154 (Substances - Toxic and/or Corrosive (Non-Combustible)).

The two rows differ by packing group. 172.101(f) says packing groups I, II and III indicate the degree of danger presented is great, medium or minor. Packing group II carries B2, IB2, N34, T7, TP2; packing group III carries IB3, N34, T4, TP1. The non-bulk packaging section is 173.202 for packing group II and 173.203 for packing group III, and the bulk sections are 173.242 and 173.241.

The full rows from the eCFR copy of the table, current through October 29, 2026 and read November 2, 2026, are below. Every value is copied from 49 CFR 172.101; the last column is the regulation's own explanation of the column.

The 172.101 rows, column by column

How the regulation defines the hazard class

173.136(a) says, abridged: ""corrosive material" (Class 8) means a liquid or solid that causes irreversible damage to human skin at the site of contact within a specified period of time. A liquid, or a solid which may become liquid during transportation, that has a severe corrosion rate on steel or aluminum based on the criteria in 173.137(c)(2) is also a corrosive material."

Special provisions on this entry, in the rule's words

Column 7 does not explain itself; each code is defined in 172.102. These are the definitions as printed in the eCFR text for the codes listed on the rows. Where a provision ends with a list of conditions that this page does not reproduce, it says so.

• B2 (PG II): MC 300, MC 301, MC 302, MC 303, MC 305, and MC 306 and DOT 406 cargo tanks are not authorized.
• IB2 (PG II): Authorized IBCs: Metal (31A, 31B and 31N); Rigid plastics (31H1 and 31H2); Composite (31HZ1).
• N34: Aluminum construction materials are not authorized for any part of a packaging which is normally in contact with the hazardous material.
• IB3 (PG III): Authorized IBCs: Metal (31A, 31B and 31N); Rigid plastics (31H1 and 31H2); Composite (31HZ1 and 31HA2, 31HB2, 31HN2, 31HD2 and 31HH2).

T7, TP2, T4, TP1 are portable tank instructions or provisions, defined in 172.102(c)(7) and (c)(8). They are on the row but are not reproduced on this page.

What else to know about this entry

B2 says MC 300, MC 301, MC 302, MC 303, MC 305, and MC 306 and DOT 406 cargo tanks are not authorized, which is a bulk packaging restriction for packing group II only. N34 says aluminum construction materials are not authorized for any part of a packaging which is normally in contact with the hazardous material, on both rows. IB2 and IB3 list authorized intermediate bulk containers; the IB2 text adds that only liquids with a vapor pressure less than or equal to 110 kPa at 50 degrees C (or 130 kPa at 55 degrees C) are authorized.

Column 10A gives stowage category A, so the material may be stowed on deck or under deck on a cargo vessel or on a passenger vessel, and column 10B code 52 reads "Stow separated from acids" in 176.84. Compare that with UN1830 sulfuric acid, which has category C and the codes 14, 53 and 58.

Air quantity limits and a worked example

Columns 9A and 9B give the largest net quantity allowed in one package: column 9A for passenger-carrying aircraft or passenger-carrying rail car, column 9B for cargo aircraft only. 172.101(j) says "Forbidden" means the material may not be offered for transportation or transported in the applicable mode, and that the limit is net unless stated otherwise. For UN1824 the PG III row shows 5 L in column 9A and 60 L in column 9B.

Worked example, 10 L net in one package. Passenger aircraft or rail car (column 9A, 5 L): over 5 L. Cargo aircraft only (column 9B, 60 L): within 60 L. The calculator above applies the same comparison to the quantity you type.

Rows differ, so choose the row first: PG II is 1 L in column 9A and 30 L in column 9B; PG III is 5 L in column 9A and 60 L in column 9B.

Highway placard check

Class 8 is on Table 2 of 172.504(e) as CORROSIVE.

For Table 2 materials moved by highway or rail, 172.504(c) says placards are not required on a transport vehicle or freight container that contains less than 454 kg (1,001 pounds) aggregate gross weight of hazardous materials covered by Table 2, except for bulk packagings and hazardous materials subject to 172.505. In the calculator, 1,000 pounds of non-bulk Table 2 material returns "not required" and 1,001 pounds returns "required", and any bulk packaging returns "required". The weight is the aggregate gross weight of all Table 2 materials on the vehicle, not just this one UN number.

Vessel stowage and the ERG guide

Column 10A gives category A (the material may be stowed "on deck" or "under deck" on a cargo vessel or on a passenger vessel). Column 10B lists 52. Code 52 in 176.84: Stow "separated from" acids. These apply to shipments by vessel and have no effect on a truck-only move.

The Emergency Response Guidebook 2024 numerical index lists UN1824 under Guide 154, titled "Substances - Toxic and/or Corrosive (Non-Combustible)". 172.101 itself does not list ERG guide numbers; the guide number comes from the PHMSA guidebook. The guide is for first responders during the initial phase of an incident and is not a shipping-paper or compliance document.

What this page does not do

It reproduces the table rows and the regulation text it points to, and applies the air-limit and 1,001 pound placard comparisons to numbers you enter. It does not classify a product, pick a packing group, decide which table row applies to your shipment, or replace the packaging sections the row points to (the 173 sections in columns 8A to 8C), the marking, labelling and shipping paper rules in part 172, or hazmat training. Hazardous materials employees must be trained; that decision and the shipping description belong to a trained person. The eCFR header for 172.101 links an amendment published at 91 FR 49310 (August 4, 2026); confirm that the version you rely on includes the latest changes. In an emergency call 911 and the emergency response telephone number on the shipping paper.

Sources

Sources opened and read November 2, 2026. Regulation text was read from the eCFR API, which publishes the current Code of Federal Regulations.

• 49 CFR 172.101, Hazardous Materials Table (eCFR text current through October 29, 2026; read November 2, 2026)
• 49 CFR 172.102, Special provisions (read November 2, 2026)
• 49 CFR 172.504, General placarding requirements (read November 2, 2026)
• 49 CFR 173.136, hazard class definitions (read November 2, 2026)
• 49 CFR 176.84, Other requirements for stowage, cargo handling, and segregation (read November 2, 2026)
• PHMSA: Emergency Response Guidebook 2024 English PDF, numerical index (read via the Internet Archive capture of October 31, 2026; read November 2, 2026)