If you work with planes, you need deicers ready to go whenever temperatures drop. Ice on plane wings is a common cause of crashes, and you never want to see any plane, even those with deicing capabilities built into the wings, try to fly without getting rid of the ice. Airports will have heavy-duty deicing machinery available, but a few portable units help you get more planes prepared to fly when the regular machinery is in high demand. Different types of portable units are available, and which one you choose depends on how much deicing you have to do and what your preference is for carrying the unit.
You'll find backpack-style tanks and handheld tanks that look a bit like fire extinguishers among portable deicer styles. Backpack tanks tend to have larger capacities, usually around four gallons or so, while handheld tanks can be half that or smaller. If you know you'll use a lot of deicer, the backpack style might be better. That's not to say you can't order both styles; that gives workers a choice when they have different places to deice.
A backpack-style tank is going to be hands-free, of course. If you don't want to deal with holding the tank as you move around the plane, then getting one you can wear on your back is best. The fire-extinguisher style is not hands-free, but is smaller and lighter, so it shouldn't be difficult to carry it around. However, that style will require you to use only one hand to direct the spraying wand. For new users, that might seem a bit awkward until you get used to what it's like to use the apparatus.
The fire-extinguisher tanks are slimmer than the backpack tanks, so of course you'll be able to store more of those on a shelf. But the backpack tanks may also be stackable, depending on the manufacturer and the exact shape of the tank, which would make them easier to store more of them without adding shelving. And, as mentioned, it may be best to get both types so that people have a choice when they need to grab deicing tools.
Portable aircraft deicing equipment is small enough — this goes for both styles — that buying the "wrong" style at first won't be much of a problem as long as you have enough deicing solution for all the planes at the airport. Both styles are also affordable. Give one style a try, and if that style isn't enough for you, you can always switch to the other.