UN 1826 — Nitrating acid mixture, spent, with not more than 50% nitric acid
Placard: Corrosive. ERG Guide 157. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1826 is Nitrating acid mixture, spent, with not more than 50% nitric acid, a spent corrosive nitrating acid mixture assigned to ERG Guide 157. Residual nitric acid, sulfuric acid and process contamination can create oxidizing, fuming and heat-on-dilution hazards.
Hazard overview: UN 1826 presents strong acid burns, oxidizing residue, nitrogen oxide/sulfur oxide fume and contaminated-runoff hazards. Keep organics, reducing agents and incompatible absorbents away.
Response guidance: For a UN 1826 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 157. Establish incident command, isolate the area, stay upwind, prevent incompatible contact, control runoff and choose entry or fire-control actions based on monitoring, SDS and local SOP.
Firefighter training notes: Training for UN 1826 should emphasize strong acid burns, heat from dilution, fume control, incompatibility with organics/metals where relevant, runoff containment and decontamination. Use ERG 157, SDS and local SOP.
Regulatory context: Nitrating acid mixture, spent, with not more than 50% nitric acid is regulated as a hazardous material for transportation and emergency response purposes. Transportation, workplace exposure, spill reporting, waste handling, storage and environmental requirements may vary by concentration, formulation, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, facility documents and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Nitrating acid mixture, spent, with not more than 50% nitric acid should be stored in compatible acid-resistant containers with secondary containment, away from water, bases, organics, combustibles, reducing agents where incompatible, reactive metals and unauthorized access. Keep containers closed and protected from heat and contamination.
UN 1826 Quick Details
Common Hazards of UN 1826
- CORROSIVE spent nitrating acid mixture; inhalation, ingestion or skin/eye contact may cause severe injury.
- Contains residual nitric acid and strong acid, with oxidizing and nitrating residues possible.
- Dilution with water can generate extreme heat, spattering and dense acid fumes.
- Can react dangerously with organics, combustibles, reducing agents or contamination.
- Heating or decomposition may release nitrogen oxides and sulfur oxides.
- Runoff may be strongly acidic, oxidizing and environmentally hazardous.
- Exact hazards vary with spent-acid composition and contamination.
Chemical Identity & Physical Properties
Colorless to pale yellow or brownish liquid mixture, primarily containing sulfuric acid with residual nitric acid (≤50%). Corrosive with acrid, choking fumes. Dense, oily consistency typical of concentrated sulfuric acid.
| Also known as | Spent nitrating acidSpent mixed acidWaste nitrating mixtureNitric-sulfuric acid waste |
| Appearance | Colorless to pale yellow or brownish liquid mixture, primarily containing sulfuric acid with residual nitric acid (≤50%). Corrosive with acrid, choking fumes. Dense, oily consistency typical of concentrated sulfuric acid. |
| Flash Point | Not applicable (non-flammable liquid) |
| Boiling Point | Varies with composition, typically >150C (302F) due to high sulfuric acid content |
| Vapor Density | Heavier than air; concentrated acid vapors settle in low areas |
| Water Reactivity | Reacts violently with water generating extreme heat and spattering; adds acid to water slowly, never reverse |
Fireground Response Guidance — UN 1826
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for dust, vapor, mist, fire or confined-space exposure. Wear chemical-resistant gloves, boots, eye/face protection and protective clothing selected from SDS for corrosive contact.
Isolation & Evacuation
First Actions for a UN 1826 Incident
- CALL 911. Then call the emergency response telephone number on the shipping paper, if available.
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Avoid breathing vapors, fumes, dust, mist or spray and avoid skin or eye contact.
- Keep organics, combustibles, reducing agents and contaminated absorbents away from the material.
- Do not touch or walk through spilled material unless properly trained and wearing appropriate protective equipment.
- Ventilate closed spaces before entering, but only if properly trained, equipped, monitored and authorized by incident command.
- Isolate the spill or leak area and expand the perimeter if vapor, dust, fire involvement, water reaction or unknown concentration is present.
- Use ERG Guide 157, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1826 — Nitrating acid mixture, spent, with notUse 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.