UN 2681

CAESIUM HYDROXIDE SOLUTION

Class 8 — Corrosive SubstancesPacking Group II2 variants
UN 2681 has 2 classification variants in ADR 2025 — different hazard divisions or descriptions for the same UN number. Each variant may have different transport requirements.
UN 2681Class 8 — Corrosive SubstancesPG IIVariant 1 of 2
CAESIUM HYDROXIDE SOLUTION
Packing Group
II
Medium danger
Classification Code
C5
Tunnel Code
(E) meaning →
Code governing tunnel passage
Transport Category
2
For the 1,000-point rule (0 = highest restriction)
Hazard ID No.
80
Kemler code
Limited Quantity
1 L
Max per inner package for LQ relief
Excepted Quantity
E2
EQ code for excepted quantity relief
Thresholds — why, not just the verdict
Transport Category
Category 2
×3 points per kg/L — up to 333 kg/L of this substance alone stays under the 1,000-point threshold
Per-substance max
333 kg/L
Per-substance maximum for 1.1.3.6 relief (1.1.3.6.3)
Limited Quantity
1 L
Max per inner packaging for LQ relief (Chapter 3.4)
Excepted Quantity
E2
Max 30 ml/g per inner, 500 ml/g per outer package (Chapter 3.5)
Tunnel Code
Governs which tunnel categories the load may pass
Hazard Labels Required
Label 8

These labels must be displayed on packages and vehicle placards in accordance with ADR 2025.

UN 2681Class 8 — Corrosive SubstancesPG IIIVariant 2 of 2
CAESIUM HYDROXIDE SOLUTION
Packing Group
III
Low danger
Classification Code
C5
Tunnel Code
(E) meaning →
Code governing tunnel passage
Transport Category
3
For the 1,000-point rule (0 = highest restriction)
Hazard ID No.
80
Kemler code
Limited Quantity
5 L
Max per inner package for LQ relief
Excepted Quantity
E1
EQ code for excepted quantity relief
Thresholds — why, not just the verdict
Transport Category
Category 3
×1 points per kg/L — up to 1,000 kg/L of this substance alone stays under the 1,000-point threshold
Per-substance max
1,000 kg/L
Per-substance maximum for 1.1.3.6 relief (1.1.3.6.3)
Limited Quantity
5 L
Max per inner packaging for LQ relief (Chapter 3.4)
Excepted Quantity
E1
Max 30 ml/g per inner, 1,000 ml/g per outer package (Chapter 3.5)
Tunnel Code
Governs which tunnel categories the load may pass
Hazard Labels Required
Label 8

These labels must be displayed on packages and vehicle placards in accordance with ADR 2025.

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ADR 2027 (accepted)

ADR 2027 was accepted: depositary notification C.N.395.2026 (9 October 2026) records no objection to the amendments proposed by C.N.252.2026. It applies from 1 January 2027, and ADR 2025 may still be applied until 30 June 2027 (1.6.1.1). (C.N.395.2026)

The ADR 2027 amendments (ECE/TRANS/WP.15/274, ECE/TRANS/WP.15/274/Add.1, ECE/TRANS/WP.15/274/Corr.1) make no change to this entry's Table A columns. Other parts of ADR 2027 may still affect its carriage.

ADR 2025 remains the edition FreightUtils serves and the one that applies until ADR 2027 takes effect on 1 January 2027; after that, ADR 2025 may still be applied until 30 June 2027 (1.6.1.1).

All ADR 2027 Table A changes →

Other Corrosive Substances near UN 2681 (Class 8)

UN 2678
RUBIDIUM HYDROXIDE
UN 2679
LITHIUM HYDROXIDE SOLUTION
UN 2680
LITHIUM HYDROXIDE
UN 2682
CAESIUM HYDROXIDE
UN 2683
AMMONIUM SULPHIDE SOLUTION
All Class 8 UN numbers →
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📅Data: UNECE ADR 2025 (ECE/TRANS/352), via EU Directive 2008/68/EC. Last verified August 2026

ADR reference data only. Classification is the consignor's legal responsibility. Consult a DGSA for compliance decisions.

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