In Half-Life, Half-Life: Opposing Force, and Half-Life: Blue Shift, fire extinguishers in glass boxes can be found mounted on the walls:
If damaged, they will explode, causing a small amount of cold damage to the player, indicated by a snowflake symbol on the HUD.
Is there any use for these?
Best Answer
According to the Half life wiki page on Fire Extinguishers, fire extinguishers in the original Half Life were not usable items (emphasis mine):
However, just because it is unusable does not mean it does not serve any function. As you mentioned in your question, when damaged they can explode, causing cold damage to anything close to them. I could not find any sources confirming this, but I do know from my own playing that at the very least this explosion will damage you as the player (though I do not know if it will also damage enemies as well - I don't remember a time when there were enemies around I could attempt to damage using the wall-mounted fire extinguisher).