Hi General Lighting ,
Your right in the old days the colour of the extinguisher told you the type it was , as well as the writing on it . Now with EU regs , they are all red with writing and most put a colour band on as well ( for people that dont read or are foreign ) . I do think the old system was better as you just saw colour and knew straight away .

I know what you mean by bcf and co2 drenching systems in frame rooms or any electrical board rooms . Nasty shit , some places i used to work at the room would seal and drench the room in a secondary agent . Basically the room was starved of oxygen by the secondary agent , no oxygen no fire . Unfortunetly if you didnt get out in time …….you died !!!! unless you had rescue sets in the room .

regards
Mungo