In the interest of keeping my insulin as cool as possible I've purchased 6 Frio wallets. These wallets use direct evaporative cooling to maintain a reasonably cool temperature for up to 45 hours at a time, the degree of temperature does however depend on the environmental temperature and moisture content. The wallets contain crystals that retain water, as the water evaporates from the crystals, the air is cooled resulting in a cooler temperature inside the wallets. The wallets can be used continually by reimmursing in water to soak the crystals again.
I have now had Insulin (Novorapid & Lantus) out of the refrigerator and in a Frio wallet for a month. The Frio wallet has been laying in an open environment with unrestricted air movement and very low humidity in temperatures ranging from 19 - 40ºC. I have recently used the insulin in my normal manner, no refrigeration and no temperature protection until used, and there was no noticeable difference between the insulin kept refrigerated and that kept in the Frio wallet.
It goes without saying that If the wallets containing the insulin were kept inside a sealed pannier it would be very difficult for sufficient evaporation to take place, quite possibly resulting in overheated, dead insulin. I considered different ways to carry the wallets in a more open environment, but the following seemed the best option. Those of you familiar with Pelican cases are going to be horrified with my actions but the 1400 case proved the best starting point for this project.
Pelican case, a set on Flickr.
The 1400 case is the perfect size to carry 6 Frio wallets which will allow me to travel without continually needing to locate fresh insulin stocks. Pelican cases are 'bullet proof' and guaranteed for life, although I'm sure I've forfeited my right to warranty. I don't wish to travel with a top box as well as the aluminium panniers because of the high weight (high as in high centre of gravity), so there was spare room on the rack for the lightweight Pelican case. I mounted the case on the rack using one of the rack mounting points with a longer bolt and 2 bespoke stainless steel U bolts. It played havoc with my conscience just drilling holes through the case for mounting purposes but then I had to cut gaping holes left, right and centre, quite literally, in order to fit louvre vents. I fixed aluminium louvre vents both inside and out in order to maintain the strength and rigidity of the case. The result is a tough little box, securely mounted and strong enough to withstand knocks. It should have more than enough airflow to enable the necessary evaporation for the Frio wallets to work at their peak. The effectiveness of this project will be tested on my run to Kalgoorlie in a couple of weeks time, but fingers crossed this should help!
There are many medications that maintain their usefulness longer if they are kept at lower temperatures, and this could be an option for anyone needing to travel with them whilst keeping them secure.
Pelican cases are moulded plastic containers that seal with an airtight and watertight gasket. They have a barometric relief valve made of Gore-Tex to prevent barotrauma to the case during transportation, or when the air pressure in the environment may change. Most come with Pick'n'Pluck™ foam to enable secure transportation of fragile items. These cases are available in a variety of sizes, colours etc, a calculator can be found here. Pelican cases feature a lifetime guarantee, but obviously... I wrecked mine!