HazMat Tool — substance information

Nitric oxide and dinitrogen tetroxide mixtures or Nitric oxide and nitrogen dioxide mixtures

HMT May 2026

UN / ID: UN 1975
Hazard class: 2.3
Packing group: —
ERG guide: ERG 124
Special provisions: SP 1, SP B77
Source: 49 CFR §172 (2026/05)

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Nitric oxide and dinitrogen tetroxide mixtures or Nitric oxide and nitrogen dioxide mixtures

Emergency Response Guide No. 124

Hazardous Materials Table

Source: 49 CFR §172 (2026/05)

(3) Hazard Class

2.3
Poisonous gas

(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.

1	This material is poisonous by inhalation (see §171.8) in Hazard Zone A (see §173.116 or §173.133), and must be described as an inhalation hazard under the provisions of this subchapter. Browse special provision 1
B77	Other packaging are authorized when approved by the Associate Administrator. Browse special provision B77

(8) Packing Authorizations (§173.***)

(8A) Exceptions	None
(8B) Non-bulk	337	see 49 CFR §173.337
(8C) Bulk	None

(9) Quantity Limits

(9A) Passenger aircraft/rail	Forbidden
(9B) Cargo aircraft only	Forbidden

(10) Vessel stowage

(10A) Location

Stowage category “D” means the material must be stowed “on deck only” on a cargo vessel or 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, but the material is prohibited on a passenger vessel in which the limiting number of passengers is exceeded.

Source: 49 CFR §172.101(k)

(10B) Other

40	see 49 CFR §176.84
89	see 49 CFR §176.84
90	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: In this segregation and separation chart are HazMat of hazard class 2.3 considered depending on their poisonousness by inhalation (Hazard zone A). See special provision 1 and PHMSA Interpretation #09-0252.

Hazard class	8	7	6.1	5.2	5.1	4.3	4.2	4.1	3	2.3B	2.3A	2.2	2.1	1.6	1.5	1.4	1.3	1.1/1.2
1.1/1.2
1.3
1.4
1.5
1.6
2.1
2.2
2.3A
2.3B
3
4.1
4.2
4.3
5.1
5.2
6.1
7
8

	Must not be loaded, transported, or stored together in the same vehicle or facility.
	May be loaded, transported, or stored together.
	May be loaded, transported, or stored together only with restrictions.

Similar substances

UN / ID	Proper shipping name	Hazard class
UN 2556	Nitrocellulose with alcohol with not less than 25 percent alcohol by mass, and with not more than 12.6 percent nitrogen, by dry mass	4.1
UN 2059	Nitrocellulose, solution, flammable with not more than 12.6 percent nitrogen, by mass, and not more than 55 percent nitrocellulose	3
UN 2557	Nitrocellulose, with not more than 12.6 percent nitrogen, by dry mass mixture with or without plasticizer, with or without pigment	4.1
UN 1040	Ethylene oxide or Ethylene oxide with nitrogen up to a total pressure of 1 MPa (10 bar) at 50 degrees C	2.3
UN 3270	Nitrocellulose membrane filters, with not more than 12.6% nitrogen, by dry mass	4.1
UN 1058	Liquefied gases, non-flammable charged with nitrogen, carbon dioxide or air	2.2
UN 1977	Nitrogen, refrigerated liquid cryogenic liquid	2.2
	Nitrogen triiodide monoamine	Forbidden
UN 1066	Nitrogen, compressed	2.2
UN 1067	Dinitrogen tetroxide	2.3
	Nitrogen trichloride	Forbidden
UN 2451	Nitrogen trifluoride	2.2
	Nitrogen triiodide	Forbidden
UN 2421	Nitrogen trioxide	2.3