According to answers to this question there seem to be a standardized notation on fuses. For example F8AL250V means that it's a 8A fast fuse.
On the other hand there is answers this question stating the importance of checking the datasheet for specifications on when the fuse should blow.
Pulling these answers together appears to be contradicting. While F8AL250V says 8A fast fuse you seem to have to consult the datasheet to find out what that means (which makes the notation doesn't mean anything in particular). This would also be unfortunate since it would require an end user to consult datasheets (he's not likely to understand) instead of just insisting him to use the F8AL250V fuse.
Is there a standard of requirements on fast and slow fuses regarding time-current characteristics? What does the standard say about the time before the fuse blows for various over-currents?
My specific situation is that I'm considering a power supply (Velleman FPS1320M), the load may briefely draw more than 8A. The question is if a fast 8A fuse will be adequate. For example what amount of time can I expect the fuse to withstand 16A at a minimum (I don't have the number, but I think it's just needed to last for a minute or so) and how fast can I expect it to blow (according to the PS manual it has to blow within two hours). How fast can I expect it to blow at 20 or 22A (needs to blow within 30 respectively 1 minute).