HazMat Tool — substance information

Rubidium

HMT May 2026
UN / ID
UN 1423
Hazard class
4.3
Packing group
I
ERG guide
ERG 138
Special provisions
SP 22, SP A7, SP A19, SP IB4, SP IP1, SP N34, SP N40, SP N45, more…
Source
49 CFR §172 (2026/05)

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Rubidium


Rubidium is a chemical element; it has symbol Rb and atomic number 37. It is a very soft, whitish-grey solid in the alkali metal group, similar to potassium and caesium. Rubidium is the first alkali metal in the group to have a density higher than water. On Earth, natural rubidium comprises two isotopes: 72% is a stable isotope 85Rb, and 28% is slightly radioactive 87Rb, with a half-life of 48.8 billion years – more than three times as long as the estimated age of the universe. German chemists Robert Bunsen and Gustav Kirchhoff discovered rubidium in 1861 by the newly developed technique, flame spectroscopy. Wikipedia

Emergency Response Guide No. 138

Hazardous Materials Table

Source: 49 CFR §172 (2026/05)

(3) Hazard Class

4.3
Dangerous when wet materials

(4) Identification number Help

UN 1423

(5) Packing Group Help

I

(6) Labels Help

Dangerous when wet materials (4.3) Cargo Aircraft Only (Cargo Aircraft Only)

(7) Special Provisions (§172.102) Help

×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.
22
A7
A19
IB4
IP1
N34
N40
N45
W31

(8) Packing Authorizations (§173.***) Help

(8A) ExceptionsNone
(8B) Non-bulk211see 49 CFR §173.211
(8C) Bulk242see 49 CFR §173.242

(9) Quantity Limits Help

(9A) Passenger aircraft/railForbidden
(9B) Cargo aircraft only15 kg

(10) Vessel stowage Help

(10A) Location
(10B) Other

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.

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

Similar substances

UN / IDProper shipping nameHazard class
UN 2677Rubidium hydroxide solution8
UN 2678Rubidium hydroxide8