stupid dryer belt tensioner design

I had a LOT of fun one night. This was when I was fairly inexperienced. These sites had a steam boiler to generate steam for the dry cleaner and steam iron equipment, and an immersed hot water coil to heat water for the wash machines. The coil had become lime plugged, and I was going to clean it out. I got some coil acid from my other job (refrigeration/ HVAC place) and borrowed the acid pump. These work by rotating a roller equipped device against a hose, so the acid never touches metal in the pump

The boiler of course was still pretty hot. I'd guess it was at least 500 gal, maybe more

Anyhow I diluted the acid "about what I thought" (had gotten some advice from the mech at work) and hooked it up. But the HEAT OF THE BOILER greatly accelerated the acid and the activity got out of hand. We "almost" had a mess there for a bit.