Friday, November 11, 2011

Can I Mail Backpacking Gas Canisters? YES! If ...

OK, first, I'm talking about domestic US Mail (USPS) in the contiguous 48 US states only.  This post does NOT apply to packages sent outside the United States.  This post does not apply to UPS, FedEx, or other private shippers.  I'm just talking about US Mail (USPS) within the contiguous 48 states – surface mail only.  No air mail.  No international mail.  No Alaska.  No Hawaii.  No overseas APO's or FPO's.

First, you generally can't send fuel in the US Mail, but there are exceptions.  The exceptions are for what is called "Otherwise Restricted Material – Domestic" (ORM-D), material in other words, that would otherwise be restricted but is NOT under certain conditions.  The conditions?  The conditions are laid out in USPS Publication 52.  See below for relevant sections.

NOTE:  If you refill your own canisters, check with the Postal Service before mailing.  I suspect that refilled canisters cannot be mailed.

Here's a summary:
  • The canisters must contain butane mixes.  This is not a problem since that's what backpacking canisters contain.
  • The volume of the canisters cannot be more than one liter (but multiple canisters may be included in one package).  This is not a problem because backpacking canisters are smaller than one liter in volume.  A 450 g canister is about 780 ml of fluid for example.
  • Canisters have to be well packaged.  Use a good strong box and plenty of tape.
  • You have to label the package "ORM-D, Consumer Commodity, Surface Only."
  • Canisters have to be padded against shock.  In other words you can't just throw some canisters in a box and mail it.  You need to use bubble wrap, wadded up newspaper, artificial "peanuts", or other similar packing materials to absorb any shocks during shipping.
So, can you mail backpacking gas canisters? Yes – if you meet the conditions.

And of course, be up front with the USPS.  Tell them what you're doing, show them the relevant sections from Publication 52 (best printed from the USPS website, not my clips), and show them how you've labeled everything properly.  Some people have reported having problems with postal workers that simply won't believe that a flammable gas can be mailed – even after being shown the relevant portions of Publication 52. Your best bet then is to either ask to speak to a supervisor or to just take it to another post office.


From USPS Publication 52:

342.1 Definition

Hazard Class 2 consists of three divisions:

Division 2.1, Flammable Gases. A material that is a gas at 68° F (20° C) or less and 14.7 psi (101.3 kPa) of pressure. Flammable gases also include materials that have a boiling point of 68° F (20° C) or less at 14.7 psi (101.3 kPa) and that are ignitable at 14.7 psi (101.3 kPa) when in a mixture of 13 percent or less by volume with air or that have a flammable range at 14.7 psi (101.3 kPa) with air of at least 12 percent regardless of the lower limit. These conditions must be established in accordance with ASTM E681–85, Standard Test Method for Concentration Limits of Flammability of Chemicals, or other approved equivalent method. The flammability of aerosols must be determined using the tests specified in 49 CFR 173.306(i).

342.22 Mailable Gases

The following are examples of mailable gases: [emphasis added]
Butane. Butane (UN1011) and Receptacles, small (UN2037) with butane or butane mixtures are Division 2.1 flammable gases. Butane gases that can qualify as ORM–D materials are acceptable only in domestic mail via surface transportation when properly prepared under 342.3 and Packaging Instruction 2A in Appendix C.
342.3 Packaging
b. Metal Containers. Mailable nonflammable and flammable compressed gases are acceptable in metal primary receptacles that have a water capacity up to 33.8 fluid ounces (1 liter or 61.0 cubic inches). The liquid content of the material and the gas must not completely fill the primary receptacle at 130° F (55° C). Additionally, the following apply:
  1. A DOT 2P container must be used if the internal pressure is from 140 psig to 160 psig at 130° F (55° C).
  2. A DOT 2Q container must be used if the pressure is from 161 psig to 180 psig at 130° F (55° C).
  3. A container with an internal pressure over 180 psig at 130° F (55° C) is prohibited from mailing.
  4. Packaging Instruction 2A or 2B, as applicable, must be followed.
c. Flammable Gases. A mailable flammable compressed gas is restricted to 4 fluid ounces in a nonmetal primary receptacle or 33.8 fluid ounces (1 liter) in a metal primary receptacle per mailpiece Packaging Instruction 2A must be followed.

Notice that in section 342.3 that b.1 and b.2 call for either a US Department of Transportation (DOT) 2P or 2Q container.  How do I know if I have a 2P or 2Q container?  Well, that is what backpacking canisters are, but you'll need to be able to show that to the Post Office.  Printed somewhere on the canister, you should see something like this:
On the canister, look for the DOT permit number, typically DOT-SP followed by some numbers.
This canister has DOT special permit 9758.
You can look these numbers up on the US Department of Transportation website on the PHMSA Special Permit List.   In the case of DOT SP 9758, we find the following:
"This special permit authorizes the transportation in commerce of a Division 2.1 material in a non-refillable, non-DOT specification inside container conforming to the DOT Specification 2P except ... "
Basically this special permit is an extension of DOT 2P and therefore meets the requirements for mailability.  You should be able to just show the DOT permit on your phone (if they even ask), but be prepared to give them a hard copy print out.


  1. Both DOT 2P and 2Q specify that the inside diameter much not exceed 3 inches.

    So far, all of the 6 ounce and 8 ounce and larger "butane-propane" backpack containers exceed this diameter allowed under DOT 2P and 2Q.


    Well, it is a messy link to the specifications.

    The DOT regulations are intended for Commercial transport of goods.

    There are claims that the small 3 ounce size canisters are OK, but the DOT number on those cans is NOT 2P or 2Q.

    My postmaster said that if the canisters actually said 2P or 2Q and the content classification was UN1075, he would accept them for hazardous mailing when properly marked as above.

    I talked with the USPS hazardous shipping office in 2008, and the gentleman in charge of the office (robert.bokor@usps.gov) agreed that it might be time to review the regulations, as it had been some time since they were reviewed.

    Portions of my email to him are below.


    I have spent about 5 days trying to figure out how to be allowed to ship by USPS backpacking butane fuel canisters to myself in care of General Delivery in isolated rural parts of my vacation hike. These containers are covered by DOT SP11914 for the 8 ounce size, and DOT SP 12562 for the 3.5 ounce size canister. Both specifications cite that they are to be used in place of DOT 2P which is what USPS Pub 52 cites.

    Most often, the first words out of the mouths of USPS staff have been "Butane is unmailable, you have to ship it some other way". They are surprised (and sometimes upset) to hear that USPS Publication 52 section 342.22a-c specifies that under certain conditions, it is indeed mailable. So, this issue is an uphill battle. I was told by an employee of the Damascus VA post office that "they don't allow those things there". Damascus is one of the major resupply points along the Appalachian Trail.... where one might want to buy and send ahead fuel for some of the long sections that have no handy retail stores which carry replacements.

    DOT 2P was evidently written in the 1960's and allows generally containers up to three inches (3") diameter and specific quality and performance tests, as well as specific packaging and labeling requirements. The backpacking butane fuel canisters popular over the last 10 to 15 years cannot be covered directly by DOT 2P because they are 4 1/4 inch or 3 1/2 inch diameter containers. DOT created the above two standards to be used in place of DOT 2P for these containers only. The specification cites specific manufacturer drawings to fix the geometry and thickness of materials.

    The local postmaster insisted that I furnish information on meeting DOT 2P for these canisters before they would be accepted, as well as naturally meeting the protective packaging requirements and the labeling.

    This problem has been ongoing for at least 10 years, and remains a standstill between postal employees and many of the postal resupply long distance hikers.

    Your suggestion that it might be time to revise Pub 52 seems timely to me. I would encourage doing it and if possible doing it in some fashion that makes the information and requirements more readily available directly to the consumer. The abundance of the "Butane is unmailable, you have to ship it some other way" comments indicates that having this information in the hands of the consumers is likely to still be needed.

  2. I've not had such a run around by the USPS before. I've marked things "ORM-D, consumer commodity, surface only," and they've accepted them. Thanks for all the detailed information on different types of containers and such. I hope that DOT does align their definitions such that it's easier to mail gas canisters.


  3. So you label them as ORM-D and don't have to pay a hazmat fee (assuming you are legitmatelly following the rules) correct?

  4. I just deleted one comment. Civil comments are welcome. Comments that are insulting or threatening will be deleted. If you have no people skills, please stay off my blog.

  5. Hi all,

    I am mailing myself the MSR fuel cans. When researching, I found this document courtesy of the USPS which clearly states that camp fuel is mailable, surface only.

    Happy Trails!

    1. Actually I don't see that any white gas is mailable. Coleman Camp Fuel has a flashpoint of <0 degrees F. Any flammable liquid with a flashpoint less than 20 degrees F is not mailable.


      "A flammable liquid having a flashpoint greater than 20° F (–7° C) but less than 100° F (38° C) is mailable in domestic mail via surface transportation, if the liquid can qualify as a consumer commodity or ORM-D material, and all applicable requirements in 343 are met.
      Flammable liquids having a flashpoint of 20° or less are not mailable."

    2. White gas (liquid fuel) is NEVER mailable. Ever.

      I think "Trek" is using "camp fuel" in the generic sense. What he really means is that canister gas is mailable, which has been my contention all along.


  6. My canister of MSR isopro which may be short for isobutane propane using isobutane as a propellant says DOT-SP119914 which may be found at https://www.phmsa.dot.gov/staticfiles/PHMSA/SPA_App/OfferDocuments/SP11914_2015011686.pdf. This DOT document says that a non permit holder may offer it for retransportation as long as the canister has not been modified. You can buy these things from amazon and such and they ship it to people like us. Makes sense that we can ship it unmodified. Also Jetboil's product description includes the ORMD desig: http://www.bikewagon.com/jetpower-fuel-100-gm-qty-24?CAWELAID=400006350000320452&CAGPSPN=pla&CAAGID=38427648600&CATCI=pla-132686034996&gclid=CjwKEAjw1PPJBRDq9dGHivbXmhcSJAATZd_BcfSvh_XAalVh_XXZ26dzi9a6YIqKoxuGGrav6h98pBoCcPPw_wcB

    1. Interesting. It says that it's permissible to ship these canisters (MSR brand) by air so long as it is a cargo-only plane. I have always been told that they couldn't fly. Still, I would mark mine "ORM-D Surface Only" which is what the US Postal Service requires.