HazMat Tool — substance information

Nitrosylsulfuric acid, liquid

HMT 15 June 2026

UN / ID: UN 2308
Hazard class: 8
Packing group: II
ERG guide: ERG 157
Special provisions: SP A3, SP A7, SP B2, SP IB2, SP N34, SP T8, SP TP2
Source: 49 CFR §172 (15 June 2026)

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Nitrosylsulfuric acid, liquid

Nitrosylsulfuric acid is the chemical compound with the formula NOHSO4. It is a colourless solid that is used industrially in the production of caprolactam, and was formerly part of the lead chamber process for producing sulfuric acid. The compound is a salt best described as NO+HSO4− (nitrosonium hydrogensulfate). It is called “lead-chamber crystals” Wikipedia

Emergency Response Guide No. 157

Hazardous Materials Table

Source: 49 CFR §172 (15 June 2026)

(3) Hazard Class

8
Corrosive liquids

(4) Identification number

UN 2308

(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 absorbent material in tightly closed rigid and leakproof receptacles before packing in outer packagings.

Browse special provision A3

Steel packagings must be corrosion-resistant or have protection against corrosion.

Browse special provision A7

MC 300, MC 301, MC 302, MC 303, MC 305, and MC 306 and DOT 406 cargo tanks are not authorized.

Browse special provision B2

IB2

_{Authorized IBCs:} Metal (31A, 31B and 31N); Rigid plastics (31H1 and 31H2); Composite (31HZ1).
_{Additional Requirement:} Only liquids with a vapor pressure less than or equal to 110 kPa at 50 °C (1.1 bar at 122 °F), or 130 kPa at 55 °C (1.3 bar at 131 °F) are authorized.

Browse special provision IB2

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	Prohibited

Browse special provision T8

TP2

a. The maximum degree of filling must not exceed the degree of filling determined by the following:
TP2a

Where:
t_r is the maximum mean bulk temperature during transport,
t_f is the temperature in degrees celsius of the liquid during filling, and
α is the mean coefficient of cubical expansion of the liquid between the mean temperature of the liquid during filling (t_f) and the maximum mean bulk temperature during transportation (t_r) both in degrees celsius.
b. For liquids transported under ambient conditions α may be calculated using the formula:
TP2b

Where:
d₁₅ and d₅₀ are the densities (in units of mass per unit volume) of the liquid at 15 °C (59 °F) and 50 °C (122 °F), respectively.

Browse special provision TP2

(8) Packing Authorizations (§173.***)

(8A) Exceptions	154	see 49 CFR §173.154
(8B) Non-bulk	202	see 49 CFR §173.202
(8C) Bulk	242	see 49 CFR §173.242

(9) Quantity Limits

(9A) Passenger aircraft/rail	1 L
(9B) Cargo aircraft only	30 L

(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
53	see 49 CFR §176.84
58	see 49 CFR §176.84
66	see 49 CFR §176.84
74	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 8 considered depending if there are liquid. Currently HazMat Tool is not able to to check if a HazMat is liquid or not. Therefore it is assumed as liquid. See 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 3456	Nitrosylsulphuric acid, solid	8