DOT transport classification

Nitric acid: UN number by concentration

Under 49 CFR 172.101, nitric acid <65% ships as UN2031 (class 8, packing group II); ≥65% and ≤70% ships as UN2031 (class 8 with a 5.1 subsidiary, packing group II); >70% ships as UN2031 (class 8 with a 5.1 subsidiary, packing group I).

CAS 7697-37-2 · Source: 49 CFR 172.101 Hazardous Materials Table

Classification by concentration

Nitric acid — 49 CFR 172.101. Percentages are by mass (w/w).
Concentration	Ships as	Class	Packing group	What we stock in this band
<65%	UN2031	8	II	Nitric Acid 5% Technical Grade Nitric Acid 20% Technical Grade Nitric Acid 25% Technical Grade Nitric Acid 30% Nitric Acid 40% Technical Grade
≥65% and ≤70%	UN2031	8 (5.1)	II	Nitric Acid 65% Technical Grade Nitric Acid 65%ACS Grade Nitric Acid 69% Technical Grade Nitric Acid ACS 69% - 55 Gallon Drum Nitric Acid 70% ACS Grade - Low Particle Nitric Acid 70% Technical Grade
>70%	UN2031	8 (5.1)	I	Nothing in this band

<65%: No oxidizer subsidiary below 65%.
≥65% and ≤70%: The common 70% ACS grade sits here: label 8 + 5.1, PG II — NOT PG I.
>70%: Red fuming nitric acid is a different entry entirely: UN2032, PG I, with both 5.1 and 6.1 subsidiaries.

How to read this

Percentages are by mass. 49 CFR 172.101 thresholds are w/w, but product labels often state volume (v/v). Near a cutoff the two can fall on opposite sides, so confirm the basis before classifying a shipment.
Products listed are verified individually. A product appears in a band only when its own reviewed classification matches it. Where a product's classification is still under review, we leave it out rather than infer it from the table.
This page is a reference, not a shipping paper. Classification for an actual shipment depends on packaging, quantity and mode; consult the current eCFR entry and the product's safety data sheet.

Source

49 CFR 172.101 Hazardous Materials Table. Reference text: “HIGHEST-RISK ENTRY. Class 8 throughout, but subsidiary and PG move with concentration: (a) <=20% => 8, PG II, NO subsidiary; (b) >20% and <65% => 8, PG II, NO subsidiary; (c) >=65% and <=70% => 8, PG II, WITH 5.1 oxidizer subsidiary; (d) >70% => 8, PG I, WITH 5.1 subsidiary. The common 70% ACS grade falls in bracket (c): label 8 + 5.1, PG II. Red fuming nitric acid => DIFFERENT UN: UN2032 (Class 8, PG I, subsidiaries 5.1 AND 6.1).”

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