☣️ UN 3524 • CLASS 2
Phosphorus pentafluoride, adsorbed
Placard: Toxic Gas. 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 3524
Class: 2
Placard type: Toxic Gas
ERG: Guide 173 (check current ERG)
Isolation: ERG 173: isolate 100m in all directions initially; if tank/railcar involved in fire isolate 800m and evacuate 1600m downwind
Chemical & Response Details
| Also known as | Phosphorus(V) fluoridePentafluorophosphorusPF5Phosphoric fluoride |
| CAS Number | 7647-19-0 |
| Appearance | Colorless gas with a pungent, irritating odor. Shipped adsorbed on inert solid material. Fumes in moist air. |
| Flash Point | Not applicable (nonflammable gas) |
| Boiling Point | -84.6C (-120.3F) |
| Vapor Density | 4.3 (heavier than air) |
| Water Reactivity | Reacts vigorously with water producing toxic and corrosive hydrogen fluoride (hydrofluoric acid) fumes |
| Extinguishing | Do not use water directly on material; dry chemical or CO2 may be used on surrounding fires |
| PPE | ⚠️ Level A recommended; SCBA with full facepiece; chemical-resistant suit and gloves due to extreme toxicity and corrosivity |
| Isolation | ERG 173: isolate 100m in all directions initially; if tank/railcar involved in fire isolate 800m and evacuate 1600m downwind |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- TOXIC; may be fatal if inhaled or absorbed through skin.
- Vapors may be irritating.
- Contact with gas may cause burns and injury.
- Fire will produce irritating, corrosive and/or toxic gases.
- Runoff from fire control or dilution water may cause environmental contamination.
- Some gases may burn or be ignited by heat, sparks or flames.
- May form explosive mixtures with air.
- Oxidizers may ignite combustibles (wood, paper, oil, clothing, etc.) but NOT readily due to low
First actions (field-minded)
- CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Many gases are heavier than air and will spread along the ground and collect in low or confined areas
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- Isolate spill or leak area for at least 100 meters (330 feet) in all directions.
- See Table 1 - Initial Isolation and Protective Action Distances.
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UN 3524 — Phosphorus pentafluoride, adsorbed HAZMAT RADIO NOTE — UN 3524
Product: Phosphorus pentafluoride, adsorbed
Class 2 / Toxic Gas / ERG 173
PPE: Level A recommended; SCBA with full facepiece; chemical-resistant suit and gloves due to extreme toxicity and corrosivity
ISOLATION: ERG 173: isolate 100m in all directions initially; if tank/railcar involved in fire isolate 800m and evacuate 1600m downwind
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 3524 — Phosphorus pentafluoride, adsorbed
Class: 2 | Placard: Toxic Gas | ERG Guide: 173
Appearance: Colorless gas with a pungent, irritating odor. Shipped adsorbed on inert solid material. Fumes in moist air.
Water Reactivity: Reacts vigorously with water producing toxic and corrosive hydrogen fluoride (hydrofluoric acid) fumes
Extinguishing: Do not use water directly on material; dry chemical or CO2 may be used on surrounding fires
PPE: Level A recommended; SCBA with full facepiece; chemical-resistant suit and gloves due to extreme toxicity and corrosivity
Isolation: ERG 173: isolate 100m in all directions initially; if tank/railcar involved in fire isolate 800m and evacuate 1600m downwind
— Key Hazards —
• TOXIC; may be fatal if inhaled or absorbed through skin.
• Vapors may be irritating.
• Contact with gas may cause burns and injury.
— First Actions —
• CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
• Keep unauthorized personnel away.
• Stay upwind, uphill and/or upstream.
• Many gases are heavier than air and will spread along the ground and collect in low or confined areas
SOURCE: allfirefighter.com/hazmat/un/3524 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3524 Phosphorus pentafluoride, adsorbed Cls2 ERG173 | allfirefighter.com/hazmat/un/3524SMS / 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/3524
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FAQ
TOXIC; may be fatal if inhaled or absorbed through skin. Vapors may be irritating. Contact with gas may cause burns and injury. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may cause environmental contamination. Some gases may burn or be ignited by heat, sparks or flames. May form explosive mixtures with air. Oxidizers may ignite combustibles (wood, paper, oil, clothing, etc.) but NOT readily due to low
CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper Keep unauthorized personnel away. Stay upwind, uphill and/or upstream.
Level A recommended; SCBA with full facepiece; chemical-resistant suit and gloves due to extreme toxicity and corrosivity
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 173 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.