HazMat Tool — substance information

Silicon tetrafluoride, adsorbed

HMT May 2026
UN / ID
UN 3521
Hazard class
2.3
Packing group
ERG guide
ERG 173
Special provisions
SP 2
Source
49 CFR §172 (2026/05)

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Silicon tetrafluoride, adsorbed


Silicon tetrafluoride or tetrafluorosilane is a chemical compound with the formula SiF4. This colorless gas is notable for having a narrow liquid range: its boiling point is only 4 °C above its melting point. It was first prepared in 1771 by Carl Wilhelm Scheele by dissolving silica in hydrofluoric acid, and later synthesized by John Davy in 1812. It is a tetrahedral molecule and is corrosive. Wikipedia

Emergency Response Guide No. 173

Hazardous Materials Table

Source: 49 CFR §172 (2026/05)

(3) Hazard Class

2.3
Poisonous gas

(4) Identification number Help

UN 3521

(5) Packing Group Help

n/a

(6) Labels Help

Poisonous gas (2.3) Corrosive liquids (8)

(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.
2

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

(8A) ExceptionsNone
(8B) Non-bulk302csee 49 CFR §173.302c
(8C) BulkNone

(9) Quantity Limits Help

(9A) Passenger aircraft/railForbidden
(9B) Cargo aircraft onlyForbidden

(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.