HazMat Tool — substance information

Osmium tetroxide

HMT 15 June 2026

UN / ID: UN 2471
Hazard class: 6.1
Packing group: I
ERG guide: ERG 154
Special provisions: SP A8, SP IB7, SP IP1, SP N33, SP N34, SP T6, SP TP33, SP W31
Source: 49 CFR §172 (15 June 2026)

On this page

Osmium tetroxide

Osmium tetroxide (also osmium(VIII) oxide) is the chemical compound with the formula OsO4. The compound is noteworthy for its many uses, despite its toxicity and the rarity of osmium. It also has a number of unusual properties, one being that the solid is volatile. The compound is colourless, but most samples appear yellow Wikipedia

Substance Data

Source: PubChem (HSDB, 04.12.2019)

CAS-Number

20816-12-0

Flash Point

n/a

Boiling Point

n/a

Emergency Response Guide No. 154

Hazardous Materials Table

Source: 49 CFR §172 (15 June 2026)

(3) Hazard Class

6.1
Poisonous Material

(4) Identification number

UN 2471

(5) Packing Group

(6) Labels

(7) Special Provisions (§172.102)

×Note:
Special provisions may be very complex. The extracts are taken from 49 CFR §172.102. Please be careful with the information, as necessary, additional conditions may be applied that are not written here. Please check the original source and report bugs.

For combination packagings, if glass inner packagings (including ampoules) are used, they must be packed with cushioning material in tightly closed metal receptacles before packing in outer packagings.

Browse special provision A8

IB7

_{Authorized IBCs:} Metal (11A, 11B, 11N, 21A, 21B, 21N, 31A, 31B and 31N); Rigid plastics (11H1, 11H2, 21H1, 21H2, 31H1 and 31H2); Composite (11HZ1, 11HZ2, 21HZ1, 21HZ2 and 31HZ1); Wooden (11C, 11D and 11F).
_{Additional Requirement:} Liners of wooden IBCs must be sift-proof.

Browse special provision IB7

IP1

IBCs must be packed in closed freight containers or a closed transport vehicle.

Browse special provision IP1

N33

Aluminum drums are not authorized.

Browse special provision N33

N34

Aluminum construction materials are not authorized for any part of a packaging which is normally in contact with the hazardous material.

Browse special provision N34

Minimum test pressure (bar)	4
Minimum shell thickness	§ 178.274(d)(2)
Pressure-relief requirements	Normal
Bottom opening requirements	§ 178.275(d)(2)

Browse special provision T6

TP33

The portable tank instruction assigned for this substance applies for granular and powdered solids and for solids which are filled and discharged at temperatures above their melting point which are cooled and transported as a solid mass. Solid substances transported or offered for transport above their melting point are authorized for transportation in portable tanks conforming to the provisions of portable tank instruction T4 for solid substances of packing group III or T7 for solid substances of packing group II, unless a tank with more stringent requirements for minimum shell thickness, maximum allowable working pressure, pressure-relief devices or bottom outlets are assigned in which case the more stringent tank instruction and special provisions shall apply. Filling limits must be in accordance with portable tank special provision TP3. Solids meeting the definition of an elevated temperature material must be transported in accordance with the applicable requirements of this subchapter.

Browse special provision TP33

W31

Non-bulk packagings must be hermetically sealed.

Browse special provision W31

(8) Packing Authorizations (§173.***)

(8A) Exceptions	None
(8B) Non-bulk	211	see 49 CFR §173.211
(8C) Bulk	242	see 49 CFR §173.242

(9) Quantity Limits

(9A) Passenger aircraft/rail	5 kg
(9B) Cargo aircraft only	50 kg

(10) Vessel stowage

(10A) Location

Stowage category “B” means

(i) The material may be stowed “on deck” or “under deck” on a cargo vessel and on a passenger vessel carrying a number of passengers limited to not more than the larger of 25 passengers, or one passenger per each 3 m of overall vessel length; and
(ii) “On deck only” on passenger vessels in which the number of passengers specified in paragraph (k)(2)(i) of this section is exceeded.

Source: 49 CFR §172.101(k)

(10B) Other

40	see 49 CFR §176.84

Source: 49 CFR §176.84

Segregation chart for load, transport, and storage

This chart shows whether loading, transport, or storage with other hazard classes is permitted, prohibited, or restricted. Based on 49 CFR §177.848.

Note: The HMR prohibit only those Division 6.1 liquids that meet the definition of a Packing Group (PG) I and Hazard Zone A. See special provision 1 and PHMSA Interpretation #09-0252.

Packages with POISON or POISON INHALATION HAZARD labels, or a POISON label displaying “PG III,” or “PG III” marked next to a POISON label may not be transported with foodstuffs, feed or any other edible material, intended for humans or animals. For exceptions see 49 CFR §177.841(e).

Scope & sources (important)Click to show CFR references

This check evaluates segregation per 49 CFR §177.848. Additional loading/unloading and handling requirements may still apply; see 49 CFR §177 Subpart B (Loading and Unloading):

§177.834 - General requirements
§177.835 - Class 1 materials
§177.837 - Class 3 materials
§177.838 - Class 4 (flammable solid) materials, Class 5 (oxidizing) materials, and Division 4.2 (pyroforic liquid) materials
§177.839 - Class 8 (corrosive) materials
§177.840 - Class 2 (gases) materials
§177.841 - Division 6.1 and Division 2.3 materials
§177.842 - Class 7 (radioactive) material
§177.843 - Contamination of vehicles