The dangerous goods shipping guide identifier for cyclohexanone—referenced as Cyclohexanone UN 1915 Class 3: DG Shipping Guide—defines a flammable-liquid transport profile rather than a general industrial solvent entry. The substance is the cyclic ketone with CAS number 108-94-1 and molecular weight 98.15 g/mol. Measured data relevant to transport classification include a closed-cup flash point of 44 °C, a normal boiling point of approximately 155.7 °C at 101.3 kPa, a relative density of 0.947 at 20 °C, and a vapour pressure of approximately 0.45 kPa at 20 °C. Under the UN Model Regulations, Class 3 applies to liquids with a flash point not exceeding 60 °C; Packing Group III applies where the flash point is not less than 23 °C and not greater than 60 °C. Cyclohexanone therefore falls within UN 1915 as a Class 3 flammable liquid in PG III.

How Does UN 1915 Fit the Packing Group III Criterion?

The PG III assignment follows the flammability criteria of the UN Manual of Tests and Criteria, Part III, Section 32.4.2. Because the flash point of cyclohexanone is above 23 °C, the substance avoids the stricter package quantity limits imposed on PG I and PG II flammable liquids, but it remains a full Class 3 hazard for packaging, marking, and segregation. The CLP classification under Regulation (EC) No 1272/2008 is Flam. Liq. 3 H226, with additional acute toxicity and irritant hazard statements relevant to safety data sheets. The multimodal classification matrix is given below.

These entries are not interchangeable across transport modes. IATA applies the lower passenger-aircraft package limit because cabin-accessible cargo is governed by more restrictive fire-suppression and ventilation assumptions. ADR/RID land transport permits larger tank and IBC operations where the flash point is above 23 °C and the equipment meets the relevant packing and tank provisions.

Within ADR/RID road and rail operations, the principal consignment risks arise from vapour pressure and solvent behaviour, not from a broad incompatibility profile. Intermediate bulk containers and drums are normally certified under packing instruction P001; metal IBCs of type 31A or 31HA1 are accepted, while plastic IBCs require compatibility verification because cyclohexanone can soften or permeate certain high-density polyethylene grades at sustained temperatures above 40 °C. Published full-scale permeation data for cyclohexanone in pigmented HDPE IBCs under prolonged solar exposure is limited; shipper field reports indicate elevated headspace vapour concentrations in southern European summer routes. Steel or composite IBCs are therefore preferred for such corridors. Pressure/vacuum relief devices on closed packages and tanks must remain operational and must not be plugged or blanked. The ADR hazard identification number 30 is displayed for tank transport, and the Class 3 flame label is required on packages.

Segregation Logic When Cyclohexanone Shares a Container with Oxidizers

The ketone group in cyclohexanone is susceptible to exothermic oxidation when contacted by strong oxidising agents such as nitric acid, chromic acid, organic peroxides, and permanganates. Under the IMDG Code 7.2.4 segregation table and corresponding ADR segregation requirements, Class 3 flammable liquids are to be separated from Class 5.1 oxidising substances. Cyclohexanone must not be co-loaded in the same freight container with concentrated nitric acid or organic peroxides; process-safety literature from adipic acid production demonstrates that cyclohexanone–nitric acid systems can release significant heat and nitrous gases. Separation from strong bases is also recommended because base-catalysed self-condensation of cyclohexanone may increase viscosity and generate light-end by-products during prolonged high-temperature storage. In marine container stuffing, segregation is achieved by separate vertical stacks, fire-resistant barriers, or physical separation adequate to prevent mixing of spills. The practice of placing oxidisers above a cyclohexanone consignment in the same stack is not compliant with standard segregation logic because leaked oxidiser can drain into the flammable liquid.

On IATA-governed consignments, the operator acceptance checklist requires the shipper’s declaration to show UN 1915, Cyclohexanone, Class 3, and PG III. Passenger and cargo aircraft accept this entry under PI 355 with a maximum net quantity of 60 L per package. Cargo aircraft only shipments use PI 366, with a maximum net quantity of 220 L per package. Single packagings are not permitted for this entry; combination packagings with absorbent cushioning compatible with ketones are required. Outer packagings must display the Class 3 flammable-liquid label, and the cargo-aircraft-only mark is mandatory where applicable. Package performance must meet the UN performance-tested packaging criteria referenced in ADR 6.1.5.3 or the equivalent IATA packaging acceptance standards. Common air-consignment errors include declaring PG II when the flash point is above 23 °C, or presenting a plastic inner receptacle that is not listed as compatible with the ketone; such discrepancies trigger reclassification or consignment rejection at the acceptance desk.

When Monitoring Vapour Pressure Triggers Tank Management Decisions

At 20 °C, the vapour pressure of cyclohexanone is approximately 0.45 kPa, but any rise in ullage temperature during intermodal transfer increases headspace concentration. Tank containers and rail tank cars used for UN 1915 therefore operate with pressure/vacuum vents set below the maximum allowable working pressure. The lower explosive limit of cyclohexanone in air is approximately 1.1 vol%, and the upper explosive limit approaches 9.4 vol% at ambient temperature. Hazardous area classification under EN 60079-10-1:2021 assigns zones around vents, pump seals, sampling points, and flange pairs. Explosion-proof motors, flame arresters, and closed sampling devices are specified for transfer operations. Open-top sampling from a transport tank is not an accepted practice because it permits vapour accumulations above 10% of the lower explosive limit. Gasket selection is material-critical: cyclohexanone swells ethylene-propylene-diene terpolymer and natural rubber, while fluoropolymer-lined gaskets and stainless steel internals are preferred in continuous service. Published elastomer compatibility tables for ketone service show that nitrile resistance is time- and temperature-dependent and should not be assumed for prolonged tank service.

In warehouse and tank-farm handling, cyclohexanone is stored in a cool, ventilated area away from ignition sources, oxidising agents, and concentrated acids. Transfer lines and receiving tanks are bonded and grounded because low-conductivity solvents can accumulate static charge; earthing resistance is maintained below 10⁶ Ω or the lower value specified in IEC TS 60079-32-1 for flammable liquids. Local exhaust ventilation maintains breathing-zone vapour concentrations below the applicable national occupational exposure limit, and area monitoring confirms that concentrations remain below 10% of the lower explosive limit. Spill containment is sized for the largest single package or tank. Because cyclohexanone is only partially miscible in water, sump design must not assume complete aqueous dilution; the undissolved organic layer can continue to feed a flammable atmosphere. Inert mineral absorbents and expanded perlite are acceptable for small spills, while drains should be sealed and diked before washing operations begin.

Cleaning and Residue Classification in Intermodal Equipment

Empty packagings and tank containers that have not been cleaned and still contain cyclohexanone residue are not automatically unregulated. Under ADR 4.1.6, an uncleaned empty packaging from a Class 3 liquid remains subject to dangerous goods rules until the residue has been removed or rendered safe. In bulk tanks, a residue level that appears visually minor may still produce a flammable atmosphere in an enclosed vessel; gas-free certification is therefore required before maintenance or repair. Wash water from tank cleaning carries dissolved cyclohexanone and must be collected as hazardous waste unless analysis demonstrates that the flash point of the spent solution is above 60 °C. Intermodal tank operators frequently specify a two-stage wash: cold detergent or dilute caustic followed by steam injection, with vapour concentration verified by photoionisation detection. The cleaned tank is purged with nitrogen or air, and the oxygen and flammability profile is checked with a calibrated gas meter before the unit returns to service. A visually dry cyclohexanone tank is not equivalent to a gas-free tank.

For spill and fire response, UN 1915 cyclohexanone is listed in the Emergency Response Guidebook as Guide 127. Fire suppression uses dry chemical, carbon dioxide, or alcohol-resistant foam. Water spray is applied to cool exposed containers rather than as a direct extinguishing stream, because cyclohexanone is only partially water-soluble and a direct water jet may spread the liquid. Firewater runoff is diked to prevent entry into drains and surface water; containment berms should be sealed before suppression begins. Emergency responders use positive-pressure self-contained breathing apparatus and chemical-protective clothing. Vapour accumulations are possible in low areas because the vapour density is approximately 3.4 relative to air, and the flash point of 44 °C means that a hot surface or static discharge can ignite residual vapours even when the liquid is not boiling.