Dichloromethane (DCM, CAS 75-09-2): Specification Grades, UN Packing Requirements, and Export Documentation

Mon, 07 Sep 2026 · HARMONY TECHNOLOGY (ZHEJIANG) CO., LTD.

Dichloromethane (DCM, CAS 75-09-2): Specification Grades, UN Packing Requirements, and Export Documentation

The short version: Dichloromethane is a single substance with three commercially distinct specification grades, a Class 6.1 toxic classification, and a low boiling point (39.6 °C) that makes packaging selection a pressure problem rather than a container-volume problem. This note sets out the parameter set that defines each grade, the analytical method behind each parameter, the UN packing rules, and the document set that must be arithmetically consistent at export.

1. Identity and Physical Constants

Two technical points often missed: DCM’s vapour is ~2.9× heavier than air and will accumulate in pits and low areas; and although it has no flash point under standard test conditions, it can be made to burn at high oxygen concentration or elevated temperature — the correct statement is “no flash point by standard method”, not “non-flammable”.

2. Specification Grades and the Parameters That Define Them

Note on stabilisers: DCM hydrolyses slowly in the presence of water and light, producing HCl. Commercial grades add a small amount of stabiliser (commonly a low-boiling amine or amylene class compound). A COA that reports assay without stating the stabiliser content is incomplete — the stabiliser is part of the specification and affects the effective purity.

3. Analytical Methods Behind Each Parameter

The COA literacy point (developed in Reading a Chinese Chemical COA): a spec line reading “conforms” without a measured value, method, and limit of quantification is a claim. The value of the COA lies in the raw numbers and the method attached to each.

4. UN Packing Requirements — Why DCM’s Boiling Point Drives the Choice

DCM boils at 39.6 °C. A container in tropical service routinely exceeds 50 °C internal temperature. The vapour pressure at 55 °C is far above atmospheric, so the packaging must be pressure-rated, not merely liquid-tight.

Filling ratio rule (IMDG 4.1.1.11 for IBCs): leave ≥ 2 % ullage at 55 °C, and calculate the fill for the maximum expected transport temperature, not the loading temperature. Loading cold in winter and shipping through the tropics is the classic overfill scenario. The stowage side of the same rule — segregation by class, cylinder grouping and temperature compensation inside one container — is set out in Dangerous Goods Mixed Loading.

Also required: the packaging must carry a UN mark with the correct packaging code, test pressure (for pressure-rated designs), year of manufacture, and country authorising the mark. See Dangerous Goods Mixed Loading for how to decode the mark element by element.

5. Export Documentation — the Consistency Requirement

Export of DCM involves four documents whose data must agree arithmetically:

Cross-check failures that stop a shipment:

• Proper shipping name mismatch — the transport name must match the IMDG entry for UN 1593, not the trade name.
• Class disagreement between SDS and DG declaration — both must state 6.1.
• REACH registration absent for the EU importer — the obligation sits with the importer (or their Only Representative), not the Chinese exporter; a shipment without it is not admissible for the EU.
• Tonnage band inconsistency — the registration tonnage must cover the annual volume being shipped.

6. Occupational and Environmental Limits (destination-dependent)

• DCM is IARC Group 2A. Occupational exposure limits vary materially by jurisdiction (e.g. EU indicative OEL 100 ppm 8-h TWA with skin notation; several jurisdictions apply stricter values or specific prohibitions in consumer products).
• EU restrictions on DCM in paint strippers apply to consumer and, with conditions, professional use — a product-application restriction distinct from transport regulation.
• Ventilation during unstuffing is required; the vapour is heavier than air and accumulates at floor level.

Technical reference on dichloromethane specification, packing and export documentation. Limits shown are commonly published specification ranges and vary by producer and destination; the governing standard for a given shipment, and the applicable IMDG edition, control in case of conflict. Occupational and product restrictions differ by jurisdiction — verify for the destination market.

What we can provide

Dichloromethane is supplied against one of three specification grades, and a grade is defined by its parameter set — so we quote the parameters, not the grade name alone:

On the same basis we can state:

• Assay and residue — the assay figure with its basis (area-% or mass-%) and the GC conditions, plus residue on evaporation for the grade supplied.
• Stabiliser content — reported as part of the specification; a stabilised product and an unstabilised one are not the same article.
• Batch documentation — the certificate of analysis for the batch actually shipped, with the batch number matched to the drum or IBC label.
• Grade alignment — where your specification is written to different water or acidity limits, which supplying grade the limit maps to and where the figure sits against it.

Contact us with: the grade, the parameter limits your specification sets, and the destination market.

Prepared by HARMONY TECHNOLOGY (ZHEJIANG) CO., LTD. — trading company; the group’s operating entity for this product line.