UN 3508 — Capacitor, asymmetric
Placard: Miscellaneous. ERG Guide 171. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 3508 is Capacitor, asymmetric, a Class 9 article assigned to ERG Guide 171. Main concerns are heat exposure, rupture, short circuit, electrolyte release and smoke from damaged units.
Hazard overview: Primary hazards include toxic exposure, fire or vapor ignition. Capacitor, asymmetric may release irritating, toxic or corrosive vapors when heated, spilled or involved in fire, so avoid contact, inhalation and incompatible materials.
Response guidance: For a UN 3508 incident, establish incident command, isolate the area, stay upwind and uphill, keep unauthorized personnel away, verify shipping papers/SDS and follow ERG 171. Use extinguishing, cooling, containment and decontamination tactics only when compatible with the material and local SOP.
UN 3508 Quick Details
Common Hazards of UN 3508
- Some may burn but none ignite readily.
- Containers may explode when heated.
- Some may be transported hot.
- For UN3508, Capacitor, asymmetric, be aware of possible short circuiting as this product is transported
- Polymeric beads, expandable (UN2211) may evolve flammable vapours.
- Inhalation of material may be harmful.
- Contact may cause burns to skin and eyes.
- Inhalation of Asbestos dust may have a damaging effect on the lungs.
Chemical Identity & Physical Properties
Solid electronic component, typically cylindrical or rectangular sealed unit containing electrolyte and electrodes. May contain organic electrolytes and activated carbon materials.
| Also known as | Asymmetric capacitorElectrochemical capacitorSupercapacitorUltracapacitor |
| Appearance | Solid electronic component, typically cylindrical or rectangular sealed unit containing electrolyte and electrodes. May contain organic electrolytes and activated carbon materials. |
| Flash Point | Not applicable (sealed electronic device) |
| Boiling Point | Not applicable (sealed electronic device) |
| Vapor Density | Not applicable (solid device) |
| Water Reactivity | No significant reaction when intact; damaged units may release electrolyte that reacts with water |
Fireground Response Guidance — UN 3508
Extinguishing Media
PPE Requirements
Level D for intact units; Level C with chemical gloves if damaged units release electrolyte; respiratory protection if thermal runaway occurs
Isolation & Evacuation
First Actions for a UN 3508 Incident
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- 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
📋 Copy & Share Field Card
UN 3508 — Capacitor, asymmetricUse for: Quick radio or face-to-face size-up. Short, structured, field-ready.
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
Use for: Quick text to command or incoming units. Fits in a single SMS.