What is the bulb in a drying tube for ?

Here is a typical drying tube




What is the purpose of the bulb ?

(YouTubers typically stuff it with cotton wool etc. which does not benefit from a bulb as the other end is plugged with cotton wool also, so the tube may as well be straight ? )

That makes sense, a small plug of cotton wool, as when searching for the answer (before asking here
one reference referd to it is an increased reservoir capacity

Thanks

Quote: Originally posted by Sulaiman

That makes sense, a small plug of cotton wool, as when searching for the answer (before asking here one reference referd to it is an increased reservoir capacity Thanks

I am only quoting an answer I was given at school, i also wanted to know . If you plug below the bulb then the plug can go in the reaction (unlikely buy hey), desiccant passes air more slowly than an empty tube, so the bulb hold the cotton plug and also gives a lager area of dry air.

I was told that is also why the bottom bit is smaller, so the plug cant get sucked in....

I use it the way I describe, but only because thats what I was told. for all I know it might just be to make them more sexy .

Funny enough I got loads without them as well.