Hazmat Segregation for E-commerce: What Can Actually Ship Together

If you sell beauty products, consumer electronics, automotive supplies, or household goods, you're probably shipping hazardous materials. Aerosols, lithium batteries, nail polish, perfume, spray paint, pool chemicals. All regulated. All with specific rules about what can and can't share a box.

This article breaks down the segregation requirements that apply when packing orders with multiple hazmat items. It's not comprehensive (the full regulations run hundreds of pages), but it covers what most e-commerce operators actually need to know.

The Nine Hazard Classes

Before getting into what can ship together, you need to know how materials are classified. The DOT uses nine hazard classes:

Class 1: Explosives Fireworks, ammunition, airbag inflators. Most e-commerce operations won't touch these.

Class 2: Gases Aerosols fall here. Hairspray, spray deodorant, spray paint, compressed air dusters. If it's pressurized and can spray, it's probably Class 2. This class has three divisions:

• 2.1: Flammable gas (most aerosols)
• 2.2: Non-flammable, non-toxic gas
• 2.3: Toxic gas

Class 3: Flammable Liquids Perfume (UN1266), nail polish (often UN1263), essential oils, hand sanitizer, paint, adhesives, fuel. Anything with a flash point below 100°F (38°C) in most cases.

Class 4: Flammable Solids Matches, certain batteries, oily rags. Less common in typical e-commerce.

Class 5: Oxidizers and Organic Peroxides Pool chemicals, hair dye with peroxide, some bleaches. These make other things burn more intensely.

Class 6: Toxic and Infectious Substances Pesticides, certain cleaning concentrates, medical specimens.

Class 7: Radioactive Smoke detectors technically qualify, though they're usually exempt.

Class 8: Corrosives Drain cleaner, battery acid, some rust removers. Acids and bases that destroy tissue or metal.

Class 9: Miscellaneous Lithium batteries (UN3481 for lithium ion packed with equipment, UN3480 for lithium ion shipped alone), dry ice, magnetized materials. The catch-all category.

How Segregation Works

The segregation requirements live in 49 CFR 177.848. The regulation includes a table that shows which classes can and cannot be loaded together.

The table uses three codes:

X means do not load, transport, or store together. Period.

O means you can load them together only if they're separated in a way that prevents the materials from mixing if packages leak. In practice, for parcel shipping, this often means separate boxes.

Blank means no restriction between those classes.

Here are the key conflicts:

Real Examples for E-commerce

Here's where it gets practical. Some common order combinations that create problems:

Beauty subscription box:

• Aerosol dry shampoo (Class 2.1, UN1950)
• Nail polish (Class 3, UN1263)
• No conflict between Class 2.1 and Class 3. These can ship together.

Same box, add pool sanitizer:

• Aerosol dry shampoo (Class 2.1)
• Pool chlorine tablets (Class 5.1 oxidizer)
• Conflict. The oxidizer must be separated from the flammable aerosol.

Home improvement order:

• Spray paint (Class 2.1, UN1950)
• Drain cleaner (Class 8 corrosive)
• Paint thinner (Class 3)
• The corrosive cannot be loaded above or adjacent to the flammable solid/liquid. Separate packaging required.

Electronics with cleaning supplies:

• Laptop with lithium battery (Class 9, UN3481)
• Aerosol screen cleaner (Class 2.1 or 2.2 depending on formulation)
• Class 9 has no segregation restrictions with other classes in the 177.848 table. These can ship together, though lithium batteries have their own packaging requirements.

Subsidiary Hazards

Some products have more than one hazard. A corrosive that's also flammable, for example. The regulations say you must apply whichever segregation rule is more restrictive.

Aerosols are a good example. UN1950 covers multiple variants:

• Aerosols, flammable (2.1)
• Aerosols, non-flammable (2.2)
• Aerosols, flammable, corrosive (2.1 with Class 8 subsidiary)
• Aerosols, toxic (2.1 or 2.2 with Class 6.1 subsidiary)

If you're shipping an aerosol with a corrosive subsidiary hazard, you need to apply both the Class 2 restrictions AND the Class 8 restrictions.

Air vs. Ground

Everything above applies to ground transport (49 CFR). Air transport adds another layer: IATA Dangerous Goods Regulations.

IATA is generally stricter. Some materials that can ship together by ground are forbidden to ship together by air. Some materials are forbidden on passenger aircraft entirely and can only go on cargo aircraft.

If your fulfillment operation ships via FedEx, UPS, or USPS and uses air routes, you need to check both sets of requirements.

Key IATA differences:

• Quantity limits are usually lower
• Some subsidiary hazard combinations are forbidden entirely
• Certain oxidizers and flammables that can technically ship together by ground cannot ship together by air
• Lithium battery requirements are more restrictive

Limited Quantity Exceptions

There's some good news. Small quantities of many hazmat items can ship under "limited quantity" provisions with reduced requirements.

For ground transport (49 CFR), limited quantity shipments are exempt from:

• Shipping papers
• Placards
• Most labeling requirements (though you still need the limited quantity mark)

The quantity limits vary by material. For Class 3 (flammable liquids) in Packing Group II, for example, inner containers can't exceed 1 liter and the outer package can't exceed 30 kg gross weight.

Limited quantity does not exempt you from segregation requirements. If two materials can't ship together in full quantities, they still can't ship together in limited quantities.

Finding the UN Number for Your Products

Every regulated hazmat has a UN number. You need this to determine the hazard class and applicable rules.

Where to find it:

1. Safety Data Sheet (SDS): Section 14 contains transport information including the UN number, proper shipping name, hazard class, and packing group
2. Manufacturer: If the SDS doesn't have it, ask
3. Product label: Sometimes printed directly on consumer products

Common e-commerce UN numbers:

• UN1950: Aerosols (covers many formulations)
• UN1266: Perfumery products
• UN1263: Paint (including nail polish)
• UN1170: Ethanol / ethyl alcohol (hand sanitizer)
• UN3481: Lithium ion batteries packed with equipment
• UN3480: Lithium ion batteries shipped alone
• UN3090: Lithium metal batteries
• UN1791: Hypochlorite solution (bleach)
• UN1760: Corrosive liquid, n.o.s.

How StoaPack Handles This

We built hazmat segregation directly into the packing optimizer. Add a UN number to your item data, and StoaPack automatically looks up the hazard class, checks compatibility against other items in the order, and assigns incompatible materials to separate packages. It also applies packing group restrictions and flags items that can't ship by air.

No manual lookup. No hoping someone catches the conflict at the pack station.

Full API documentation is at stoapack.stoalogistics.com/api/docs.

Resources

49 CFR 177.848: The actual segregation regulation ecfr.gov/current/title-49/section-177.848

DOT Hazardous Materials Table: Lists all regulated materials with UN numbers, classes, and packing requirements ecfr.gov/current/title-49/section-172.101

PHMSA Hazmat Info Center: 1-800-467-4922

IATA DGR: For air transport requirements (updated annually, requires purchase) iata.org/publications/dgr