If that is the yellow powder type, that stuff is caustic - corrodes anything of metal , powder is so fine floats in air for hours, gets in everything. Number of years ago a friends place up north was broken onto and the perps sprayed those abc units all over. He had to replace every appliance and eletrical gizmoe in the place do to corrsion from that stuff. Glad no one injured and things turned out relatively ok.
Uh oh...never heard of this. Guess what I'm doing later today...... Thank God it wasn't worse! Just bought 2 new extinguishers the other day. Need to get more...