UN 0391 — RDX and HMX mixtures, wetted
Placard: Explosive 1.1D. ERG Guide 112. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 0391 is RDX and HMX mixtures, wetted, a Class 1 explosive substance assigned to ERG Guide 112. It is shipped wetted or desensitized to reduce sensitivity, but it can become much more dangerous if it dries, heats or is contaminated.
Hazard overview: UN 0391 presents a serious explosive hazard if initiated. The wetting or desensitizing liquid reduces sensitivity during normal transport, but drying, fire exposure, shock, friction or contamination can increase detonation or deflagration risk. Damaged, leaking or drying material should be treated as extremely hazardous.
Response guidance: For a UN 0391 incident, responders should confirm the material using shipping papers, placards, package markings, SDS where applicable and ERG Guide 112. Establish incident command, isolate the area, deny entry, request law enforcement and EOD support, and withdraw personnel if fire involves the explosive material or containers.
Firefighter training notes: Training should emphasize recognizing Class 1 explosive placards, establishing command early, using standoff distance, denying entry and requesting bomb squad or EOD support. Common tactical errors include approaching packages for identification, moving damaged items, fighting fire too close and underestimating fragmentation distance. Use ERG 112, shipping papers and local explosive incident SOP.
Regulatory context: RDX and HMX mixtures, wetted is regulated as a Class 1 explosive hazardous material. Transportation, storage, quantity limits, fire code controls and reporting requirements may vary by jurisdiction. Responders should verify current requirements through shipping papers, SDS or product documents and applicable DOT, ATF, OSHA, NFPA, military, state or local authority guidance.
Storage & handling: RDX and HMX mixtures, wetted should be stored only in approved packaging, magazines or authorized explosive storage areas, separated from ignition sources, incompatible materials and unauthorized access. Packages should be protected from heat, impact, friction, moisture where relevant and physical damage according to product documentation and applicable explosive storage regulations.
UN 0391 Quick Details
Common Hazards of UN 0391
- Mass explosion hazard; RDX/HMX mixtures can detonate violently if initiated.
- Wetting or desensitizing liquid reduces sensitivity but does not remove the explosive hazard.
- Drying, leakage of wetting agent, heat, shock or friction may increase sensitivity.
- Severe blast overpressure and fragmentation may result from detonation.
- Fire may produce irritating or toxic combustion products.
- Damaged, leaking or drying material should be treated as extremely hazardous.
Chemical Identity & Physical Properties
White to pale yellow crystalline solid, wetted with water or alcohol to reduce sensitivity. Odorless or slight characteristic odor.
| Also known as | RDX/HMX mixtureCyclotrimethylenetrinitramine and Cyclotetramethylenetetranitramine mixtureOctogen and Hexogen mixturewetted high explosives mixture |
| Appearance | White to pale yellow crystalline solid, wetted with water or alcohol to reduce sensitivity. Odorless or slight characteristic odor. |
| Flash Point | Not applicable (explosive solid) |
| Boiling Point | Not applicable (decomposes before boiling) |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | No significant reaction with water; wetting agent used for stabilization |
Fireground Response Guidance — UN 0391
Extinguishing Media
PPE Requirements
For UN 0391, distance, cover and evacuation are more important than close-range PPE. Structural firefighting gear and SCBA may be used only for remote exposure protection or support roles; direct approach or handling should be limited to qualified EOD or explosive specialists under incident command.
Isolation & Evacuation
First Actions for a UN 0391 Incident
- CALL 911. Then call the emergency response telephone number on the shipping paper, if available.
- Keep unauthorized personnel away and deny entry to the hazard area.
- Stage responders upwind, uphill and outside the recommended isolation distance.
- Request law enforcement, bomb squad or EOD, hazmat and additional command resources immediately.
- Do not handle, move or disturb explosive articles unless directed by qualified explosive ordnance personnel.
- Watch for damaged packaging, leakage or drying of desensitized material and report it to incident command immediately.
- Do not fight fire involving explosives at close range; withdraw and protect life safety first.
- Protect exposures only from a safe, remote position if directed by incident command and local SOP.
- Use ERG Guide 112, shipping papers and incident command to set isolation and evacuation distances.
📋 Copy & Share Field Card
UN 0391 — RDX and HMX mixtures, wettedUse 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.