2-Propanol (CAS RN 67-63-0; isopropyl alcohol; IPA) is assigned to UN 1219, Class 3, Packing Group II in the UN Model Regulations. The classification is driven by a closed-cup flash point of approximately 12 °C measured by ISO 3679 and an initial boiling point of 82.5 °C determined by ASTM D86-23e1. These values place the liquid in Packing Group II because the flash point is below 23 °C while the initial boiling point exceeds 35 °C. Flammability limits in air at 101.3 kPa are 2.0 % by volume lower and 12.7 % by volume upper, and the vapour pressure at 20 °C is approximately 4.4 kPa. The proper shipping name for documentation is “Isopropanol (Isopropyl alcohol)”; technical IPA grades used in solvent cleaning and pharmaceutical drying operations require the same transport classification regardless of purity when water content does not raise the flash point above 60 °C. The transport requirement set for this product is captured as UN 1219 Class 3 Packing Group II: Packaging, Placarding and DG Documentation for IPA.

What Regulatory Criteria Place 2-Propanol in Packing Group II Rather Than Packing Group I?

Packing group assignment for Class 3 liquids uses the dual threshold of flash point and initial boiling point. Under 49 CFR 173.121(b)(2)(i) and ADR 2.2.3.1.4, Packing Group II includes flammable liquids with a closed-cup flash point below 23 °C and an initial boiling point above 35 °C. Packing Group I is reserved for liquids with an initial boiling point not exceeding 35 °C and a flash point below 23 °C, which excludes 2-propanol. Packing Group III would apply only when the flash point is between 23 °C and 60 °C inclusive and the initial boiling point exceeds 35 °C. Because the measured flash point of 2-propanol is approximately 12 °C, the liquid remains in Packing Group II under standard atmospheric test conditions. The flash point is method-dependent; ASTM D3828 small-scale closed-cup and ISO 3679 testing may produce values from 11 °C to 13 °C depending on purity, water content, and ignition source type. A single flash point report should therefore not be treated as an absolute constant in safety assessment.

For UN specification packaging, the Packing Group II assignment determines the required performance level: packages marked “Y” or “X” may be used, while packages marked “Z” are not permitted. This distinction appears directly in the UN mark, for example UN 1A2/Y1.4/100/23/USA/…. The “Y” designation indicates that the design type passed the Packing Group II and III tests; the “X” designation would also cover Packing Group I. For IPA, “X” packaging is acceptable but not required, and selecting “Y” packaging reduces package mass without reducing compliance.

Steel, aluminium, and high-density polyethylene single packagings are regularly used for 2-propanol in North American and European logistics. For a single steel drum marked 1A2/Y1.4/100/23, the final two test-pressure digits are the hydrostatic pressure applied during design-type testing. The minimum for Packing Group II liquids is 100 kPa. At 55 °C the vapour pressure of 2-propanol is approximately 25 kPa; multiplying by 1.5 yields 37.5 kPa, which is below the 100 kPa regulatory floor, so 100 kPa governs. The marking also carries the maximum specific gravity at which the design type was tested; for IPA at 0.785, a drum tested to specific gravity 1.4 is adequate, but filling line records should verify the actual gross mass against the marked mass. High-density polyethylene jerricans and drums undergo stacking and hydraulic tests per 49 CFR 178.605 and IMDG Code 4.1.3.6, and they should be marked with UN 3H1/Y1.4/100 or equivalent. Closure systems on 2-propanol packs require particular attention because the solvent is hygroscopic and can soften some elastomers. EPDM and natural rubber gasket grades have exhibited unacceptable volume swell in low-molecular-weight alcohol immersion; PTFE, unplasticized PVDF, and selected fluoroelastomer grades are used where long-term contact is expected. ASTM D543-21 immersion testing is the default method to verify seal compatibility when a supplier changes the cap liner or bung compound.

Combination packaging with 4G fibreboard outer boxes and glass or plastic inner receptacles must use absorbent cushioning sufficient to absorb the total liquid contents of all inner packagings for air transport. The absorbent material must be inert to 2-propanol; cellulose cushioning is acceptable, but uncoated clay-based absorbents can release fines that contaminate high-purity solvent. A production-scale packaging line therefore typically overwraps the inner receptacle in a polyethylene sleeve and positions the bottle upright before case sealing. Batch-to-batch variance in inner closure torque is a known bottleneck in IPA packaging; post-fill torque audit is conducted after 24 h at 23 °C to detect creep in HDPE closures. Packaging defects identified downstream include vapour leakage at induction-seal discontinuities and bulging of fibreboard boxes when a leaking 1 L inner receptacle saturates the absorbent pack.

Placarding thresholds separate bulk CTUs from non-bulk labelled packages

For UN 1219, the Class 3 hazard label is a diamond with a flame symbol and the number “3” in the lower corner. A label on a package is distinct from a placard on a transport unit. In US domestic road transport, Class 3 is a Table 2 placard under 49 CFR 172.504(e), meaning that non-bulk packages require a FLAMMABLE placard only when the aggregate gross weight of hazardous material covered by that hazard class is 454 kg or more; bulk packages require placards on each side and each end. A tank truck carrying 2-propanol displays the UN number either on the Class 3 placard itself or on an orange rectangular panel adjacent to each placard in accordance with 49 CFR 172.332. For rail tank cars, the UN number appears on the tank car sides and ends, and the Class 3 placard may be printed adjacent to the number.

Under IMDG Code 5.3.1.1.2, cargo transport units containing UN 1219 must display Class 3 placards on all four external faces. A CTU carrying ISO tank containers with 2-propanol in bulk must also display the UN number on the tank container itself and on the placard or orange panel attached to the CTU sides. For air transport, packages are not placarded; they require the Class 3 label and the UN number marked on the package adjacent to the hazard label on the same surface as the proper shipping name under IATA DGR 7.2.4.5. Air cargo pallets and unit load devices may require the hazard label on the exterior of the overpack if layers hide the package labels. A missing UN number on an air waybill-attached package is a frequent rejection at airline acceptance; the DG documentation for IPA is cross-checked against the package marks.

Placards must be at least 250 mm on each side, with the red background extending to the border; labels must be at least 100 mm square. The flame symbol must meet the shape requirements in 49 CFR 172.542 or the equivalent IMDG symbol. For multimodal moves, mode-specific placarding rules apply at each interchange point, and the shipper’s dangerous goods documentation must identify the placard applicability.

Shipper’s Declaration and Dangerous Goods Transport Document Field Entries

The transport document for UN 1219 must contain the following: the UN number, the proper shipping name “Isopropanol (Isopropyl alcohol)”, Class 3, Packing Group II, the number and type of packages, and the total quantity of dangerous goods with the appropriate unit of measurement. Under ADR 5.4.1.2.1 and IMDG Code 5.4.1.5.1, the sequence may vary but the elements are mandatory. For air shipments, the IATA Shipper’s Declaration for Dangerous Goods requires the same information plus the airport of origin and destination, a 24-hour emergency telephone number, and the signature of a properly trained person. The document must not contain abbreviations for the proper shipping name except as provided by the regulation. In electronic data interchange, the field mapping for UN 1219, Class 3, PG II is validated against the sender’s dangerous goods master data; mismatches between the UN packaging mark and the declared packing group are a frequent cause of withheld freight.

When limited-quantity provisions under ADR 3.4 or IATA DGR 2.7 are used, a dangerous goods transport document is not required for ground transport; instead, the limited-quantity mark is applied and the vehicle is exempt from placarding. For ADR limited quantities of UN 1219, the inner receptacle must not exceed 1 L and the outer package gross mass must not exceed 30 kg. For air limited quantities, packages must comply with the applicable Y-packaging instruction and the net quantity limit, and the “Y” marking is used. In all cases, the consignor must retain appropriate records according to the relevant mode-specific retention period.

When Air Transport Substitutions Are Made, What Changes in the Package Certification Chain?

Air transport imposes additional constraints beyond UN specification packaging. For UN 1219, Packing Group II, the applicable IATA DGR packing instruction permits a maximum net quantity per package of 1 L for passenger aircraft and 60 L for cargo aircraft, subject to carrier variation. The inner receptacle must be leakproof and surrounded by absorbent material capable of absorbing the entire contents. The outer packaging must be a UN specification combination pack of at least performance level “Y” for PG II; single packagings are not generally permitted for flammable liquids in passenger aircraft. For cargo-only aircraft, the package must bear the Cargo Aircraft Only label in addition to the Class 3 label and UN number. The package certification chain changes because the closure must withstand reduced air pressure at high altitude; under 49 CFR 173.27(c)(2) and IATA DGR 5.0.2.5, packaging for liquids transported by air must be capable of withstanding without leakage a pressure differential of not less than 95 kPa.

Production-scale air freight packaging lines for IPA often use a 2 mil polyethylene liner inside a 4G fibreboard box with a 1 L HDPE bottle. The sealed inner pack is subjected to pressure differential testing at 95 kPa as part of design-type evaluation; routine line verification uses vacuum decay or pressure hold methods with rejection limits established in the package specification. The packaging supplier’s test certificate must correlate the closure torque, liner thickness, and pressure differential performance. When a new closure supplier is introduced, ASTM D543-21 compatibility screening is repeated because closure softening under alcohol immersion can reduce the effective pressure differential capability at altitude.

Storage and dispensing of IPA drums before repacking should include flame arrestors on vents, bonding and grounding, and separation from oxidizers such as hydrogen peroxide and nitric acid. In bulk repacking facilities, a 1000 L stainless steel tote with a 1.5 bar nitrogen blanket feeds a two-head volumetric filler at approximately 40 strokes/min. The filler contact parts are 316L stainless steel and PTFE diaphragm seals. Ventilation in the packaging hall must maintain vapour concentration below 10 % of the lower flammable limit, which for IPA corresponds to 0.2 % by volume; fixed-point infrared sensors are typically set to alarm at 10 % LFL and interlock at 20 % LFL. Such operational limits are applied because 2-propanol vapour remains ignitable at low concentration and can form flammable mixtures inside partially filled drums and sumps if air exchange is interrupted.