With all due respect, this is grossly misleading. The article in question is talking about type III PFD's. Type III are not inflatable PFD's. Type III are recreational PFD's which typically only have 15.5 lbs or so of buouyancy. Inflatables are mostly Type V PFDs. While it varies with the design of the inflatable, most offer 20 lbs or so of buoyancy. The two hydrostatic, offshore inflatable, type V's that I use claim that they are produce 27 lbs of buoyancy and the literature says will turn the wearer face up.
Blow up your inflatable dinghy in the early morning before the sun hits it. Check it at noon and it will be grossly over inflated, check it again in the evening and it will be under inflated. Gases expand as they are warmed and decrease as they are cooled. An inflatable vest may not inflate to rock hard when temps are low but it will still inflate. A little addition of air via the oral inflation tube(s) will do the final touch up, but the PFD's will inflate enough to float you even in cold conditions though maybe not in North Pole cold.
" It is worth pointing out that some inflatable life jackets have a statement on the U.S. Coast Guard label that reads “DO NOT USE BELOW FREEZING”. The warning refers to the air temperature. Inflatable life jackets get their buoyancy from the pressure of the carbon dioxide gas (CO2) inside the life jacket’s bladder. As the temperature decreases, so does the CO2 pressure. Less CO2 pressure inside the life jacket’s bladder means less buoyancy."
Then there is the issue of cold vs warm air density. It is my understanding that the cartridge attached to each type V is sized to over-inflate the bladder in any air temperature and that there is a pressure relief valve that is part of the system that prevents a level of inflation that is likely to damage the bladder. The compressed gas gets very cold as it expands and enters the bladder and so the air temps, even freezing air temps are likely to be warmer than the expanded gasses in the bladder and not impact whether the bladder fully inflates.
More to the point, even though they span a nearly 25 year period from oldest to newest, and come from 3 different manufacturers and are a mix of hydrostatic and conventional, harness and non-harness, offshore and coastal, there is no warning on any of the five type V PFD's that I carry on my boat that says that any of those type V's would should not be used below freezing. I don't have any idea where that statement that some Type V's have a U.S. Coast Guard label that reads “DO NOT USE BELOW FREEZING” comes from but it does not appear to be close to universally accurate.
I may be a little prejudice on Type V's because I am a major proponent of wearing type V pdf's and have been for nearly 25 years. They are comparatively non-obtrusive even in a racing environment, and comfortable wear. As nearly non-swimmer, having taken an unexpected swim in a type V, in lots of clothing and carrying a bunch of gear, I was amazed how quickly it brought me the surface. That is in comparison to the time that was almost drowned in a type III PFD during a capsize in cold water. At best the quote in question should be at best seen as a warning to read the literature on any inflatable that you are buying or own before assuming that it will work below freezing.
I strongly believe that having a PFD that is comfortable to wear in all conditions such that people actually do wear them, potentially can save a lot of lives. In cold weather, an effective PFD (22 lbs or more of inflation and floating the wearer face up) is even more essential. Misleading posts potentially places people at unnecessary risk.