@sandyf wrote:

I have not done any of the Hazmat shops...so are those of you doing them saying that if Priority is refused due to the "no" Hazmat item tripping the Hot Alert, the shop is basically done except for purchasing 4 stamps etc? Then you can take your same package to another Hazmat shop elsewhere? That sounds fun! My friend might get my bday gift to her way after the fact but she is not expecting anything anyway so it sounds like a win/win.

@myst4au wrote:

There is a "less than 5 pounds" requirement, but that is not the only requirement. Even more critical is that the "container" holding the dry ice be vented so that the release of gaseous carbon dioxide does not cause an violent rupture of the sealed container. This is a real concern. A mole of carbon dioxide weighs 44 grams. A half pound = 226 grams = 226/44 = 5.65 moles of Carbon dioxide. At STP (standard temperature and pressure), 5.65 moles occupies 5.65 x 22.1 liters per moles = 124.865 liters of gas. That is a large volume. For those of you more comfortable with cubic feet, 124.865 liters = 4.4 cubic feet which is roughly a 1.6'' x 1.6' x 1.6' box (about 20" x 20" x 20". 226 grams of solid dry ice would occupy 146 ml or a chunk about 5.3 mm x 5.3 mm x 5.3 mm or about 2" x 2" x 2". Quite small. So, imagine a 2" x 2" x 2" metal box that suddenly has to expand to the size of 20 inches x 20 inches x 20 inches. I am hesitant to explain this. So, I am going to stop and let you figure out what happens if you have the dry ice in a sealed metal box and it get warm and the gas needs to expand.

There are probably some others on this forum who can check my calculations. I might be slightly off, but I am close. The bottom line is that simply asking about the weight of dry ice you shipping is not enough.

If you are curious, check 349.232 under 349 Miscellaneous Hazardous Materials (Hazard Class 9) at this URL: [pe.usps.com] which says in part: "Dry ice (carbon dioxide solid) is produced by expanding liquid carbon dioxide to vapor and compacting the material into blocks. When dry ice converts (dissipates) to a gaseous form, it takes in heat from its surroundings. The resulting gas is heavier than air and can cause suffocation in confined areas as air is displaced. When dry ice is enclosed in a thick metal or other restrictive type of container, internal pressure builds up and could cause the container to rupture or explode. Mailpieces containing dry ice must be handled with care because its very low temperature (about –110° F or –79° C) can cause severe burns to skin upon direct contact."

To be mailable, "Packages containing dry ice must be packed in containers that permit the release of carbon dioxide gas and conform to 49 CFR 173.217 and 175.10(a)(10)"

I worked for a multinational company which had specially trained shipping specialists who could certify compliance with 49 CFR 173.217 and 175.10(a)(10) for all of the shipping companies. I was not qualified to be one of those specialists. Unless a Sheldon Cooper (or his equivalent, not the actor playing Sheldon on the Big Bang Theory) has taken a job as a clerk, determining that it is safe to ship dry ice is way beyond the pay grade of one of the clerks (and I mean no disrespect) unless it is accompanied by a lot of special paperwork.

Edited to fix a critical typo.

@siamese5555 wrote:

@parkcitybrian wrote:

@nimbusrogue wrote:

I'm doing a few of these today. For the cupcake one, did you get asked how much dry ice was in the package? When you are rejected, what are you purchasing to get a receipt? It says you can buy a 4 pack of stamps, a greeting card, mailer, ect. but it doesn't say how much they reimburse for this purchase.

i tell them "about 1/2 lb" so the box doesn't go over the weight restriction (2 lbs ) & the USPS doesn't have "4 packs" of stamps so buy 4 @ .49 = $1.96 & get a receipt as pov & you will be reimbursed.

Whatever the weight doesn't matter because it should not be accepted with any dry ice

The USPS employee told me some dry ice was OK but he needed to know how much was in it by weight. When I said I did not know, he refused to send it Priority.