☣️ UN 2318 • CLASS 4
Sodium hydrosulphide, with less than 25% water of crystallization
Placard: Spontaneously Combustible. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
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⚠️ This page is a quick-reference aid. For real incidents: stage upwind, isolate, deny entry, request Hazmat early, and consult the current ERG + SOP/SOG.
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Quick details
UN 2318
Class: 4
Placard type: Spontaneously Combustible
ERG: Guide 135 (check current ERG)
Isolation: ERG 135: Initial isolation 100m in all directions; protective action distance 300m downwind for small spills, 800m for large spills; avoid water contact
Chemical & Response Details
| Also known as | Sodium hydrogen sulfideSodium bisulfideSodium sulfhydrateNaHS |
| CAS Number | 16721-80-5 |
| Appearance | Yellow to brick-red crystalline solid or flakes with a strong hydrogen sulfide (rotten egg) odor. Highly hygroscopic and deliquescent. |
| Flash Point | Not applicable (pyrophoric solid, ignites spontaneously on contact with moist air) |
| Boiling Point | Not applicable (decomposes at approximately 350C/662F) |
| Vapor Density | Not applicable (solid, but releases H2S gas which is 1.2 times heavier than air) |
| Water Reactivity | Reacts with water releasing toxic and flammable hydrogen sulfide gas; exothermic reaction |
| Extinguishing | Dry chemical, sand, dry dolomite, soda ash; DO NOT use water, foam, or CO2 |
| PPE | ⚠️ Level A required for large spills or confined spaces; SCBA mandatory; chemical-resistant suit and gloves; protect against moisture exposure |
| Isolation | ERG 135: Initial isolation 100m in all directions; protective action distance 300m downwind for small spills, 800m for large spills; avoid water contact |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- Flammable/combustible material.
- May ignite on contact with moist air or moisture.
- May burn rapidly with flare-burning effect.
- Some react vigorously or explosively on contact with water.
- Some may decompose explosively when heated or involved in a fire.
- May re-ignite after fire is extinguished.
- Runoff may create fire or explosion hazard.
- Containers may explode when heated.
First actions (field-minded)
- CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
- Stay upwind, uphill and/or upstream.
- Keep unauthorized personnel away.
- Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
- For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.
- For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind
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UN 2318 — Sodium hydrosulphide, with less than 25% HAZMAT RADIO NOTE — UN 2318
Product: Sodium hydrosulphide, with less than 25% water of crystallization
Class 4 / Spontaneously Combustible / ERG 135
PPE: Level A required for large spills or confined spaces; SCBA mandatory; chemical-resistant suit and gloves; protect against moisture exposure
ISOLATION: ERG 135: Initial isolation 100m in all directions; protective action distance 300m downwind for small spills, 800m for large spills; avoid water contact
ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO
Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.
=== IC HAZMAT BRIEFING ===
UN 2318 — Sodium hydrosulphide, with less than 25% water of crystallization
Class: 4 | Placard: Spontaneously Combustible | ERG Guide: 135
Appearance: Yellow to brick-red crystalline solid or flakes with a strong hydrogen sulfide (rotten egg) odor. Highly hygroscopic and deliquescent.
Water Reactivity: Reacts with water releasing toxic and flammable hydrogen sulfide gas; exothermic reaction
Extinguishing: Dry chemical, sand, dry dolomite, soda ash; DO NOT use water, foam, or CO2
PPE: Level A required for large spills or confined spaces; SCBA mandatory; chemical-resistant suit and gloves; protect against moisture exposure
Isolation: ERG 135: Initial isolation 100m in all directions; protective action distance 300m downwind for small spills, 800m for large spills; avoid water contact
— Key Hazards —
• Flammable/combustible material.
• May ignite on contact with moist air or moisture.
• May burn rapidly with flare-burning effect.
— First Actions —
• CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
• Stay upwind, uphill and/or upstream.
• Keep unauthorized personnel away.
• Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
SOURCE: allfirefighter.com/hazmat/un/2318 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2318 Sodium hydrosulphide, with less than 25% water of crystallization Cls4 ERG135 | allfirefighter.com/hazmat/un/2318SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS. Includes link to full page.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions. Page: https://allfirefighter.com/hazmat/un/2318
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FAQ
Flammable/combustible material. May ignite on contact with moist air or moisture. May burn rapidly with flare-burning effect. Some react vigorously or explosively on contact with water. Some may decompose explosively when heated or involved in a fire. May re-ignite after fire is extinguished. Runoff may create fire or explosion hazard. Containers may explode when heated.
CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper Stay upwind, uphill and/or upstream. Keep unauthorized personnel away.
Level A required for large spills or confined spaces; SCBA mandatory; chemical-resistant suit and gloves; protect against moisture exposure
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 135 and your department SOP/SOG for incident-specific protective actions.
Sources (high level): DOT/PHMSA marking & class concepts + ERG usage principles. This page does not reproduce ERG guide text—always consult the current ERG for incident-specific protective actions.