HazMat Tool — substance information

Nitrous oxide, refrigerated liquid

HMT 15 June 2026

UN / ID: UN 2201
Hazard class: 2.2
Packing group: —
ERG guide: ERG 122
Special provisions: SP B6, SP T75, SP TP5, SP TP22
Source: 49 CFR §172 (15 June 2026)

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Nitrous oxide, refrigerated liquid

Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas or nitrous, among others, is a chemical compound, an oxide of nitrogen with the formula N2O. At room temperature, it is a colourless non-flammable gas, and has a slightly sweet scent and taste. At elevated temperatures, nitrous oxide is a powerful oxidiser similar to molecular oxygen. Nitrous oxide has significant medical uses, especially in surgery and dentistry, for its anaesthetic and pain-reducing effects, and it is on the World Health Organization's List of Essential Medicines. Its colloquial name, "laughing gas", coined by Humphry Davy, describes the euphoric effects upon inhaling it, which cause it to be used as a recreational drug inducing a brief "high" Wikipedia

Substance Data

Source: PubChem (HSDB, 14.12.2019)

CAS-Number

10024-97-2

Flash Point

n/a

Boiling Point

n/a

Emergency Response Guide No. 122

Hazardous Materials Table

Source: 49 CFR §172 (15 June 2026)

(3) Hazard Class

2.2
Non-toxic, non-flammable gases

(4) Identification number

UN 2201

(5) Packing Group

n/a

(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.

B6	Packagings shall be made of steel. Browse special provision B6
T75	When portable tank instruction T75 is referenced in Column (7) of the § 172.101 Table, the applicable refrigerated liquefied gases are authorized to be transported in portable tanks in accordance with the requirements of § 178.277 of this subchapter. Browse special provision T75
TP5	For a portable tank used for the transport of flammable refrigerated liquefied gases or refrigerated liquefied oxygen, the maximum rate at which the portable tank may be filled must not exceed the liquid flow capacity of the primary pressure relief system rated at a pressure not exceeding 120 percent of the portable tank's design pressure. For portable tanks used for the transport of refrigerated liquefied helium and refrigerated liquefied atmospheric gas (except oxygen), the maximum rate at which the tank is filled must not exceed the liquid flow capacity of the pressure relief device rated at 130 percent of the portable tank's design pressure. Except for a portable tank containing refrigerated liquefied helium, a portable tank shall have an outage of at least two percent below the inlet of the pressure relief device or pressure control valve, under conditions of incipient opening, with the portable tank in a level attitude. No outage is required for helium. Browse special provision TP5
TP22	Lubricants for portable tank fittings (for example, gaskets, shut-off valves, flanges) must be oxygen compatible. Browse special provision TP22

(8) Packing Authorizations (§173.***)

(8A) Exceptions	None
(8B) Non-bulk	304	see 49 CFR §173.304
(8C) Bulk	314, 315	see 49 CFR §173.314, 315

(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

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.

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
	Hyponitrous acid	Forbidden