Eight fire crews were called to fire at a rubber factory in Plymouth.
Devon and Somerset Fire and Rescue Service (DSFRS) was alerted to the fire at the Crumb Rubber unit in Roborough at about 0740 BST.
Six fire engines were initially sent to the scene and were later joined by another two. At its a height, more than 40 firefighters were at the site.
No-one was hurt in the blaze, the fire service said, but a silo for reclaimed rubber was severely damaged.
'Bounce the water'
Fire service watch commander Tim Mockridge said: "We found that one of the hoppers, which is how they separate the crumbs of rubber from tyres, was overheating and there was a lot of dense smoke coming out.
"It was contained in a ventilated metal department, but shortly afterwards that ignited and the ventilation system took it across two or three hoppers and all were alight.
"They [firefighters] had a lot of difficulty getting to the hoppers because they're about 5m off the ground, so they had to bounce the water off the ceiling and into the top of the hoppers."
The site was returned to the control of its managers by 1330 BST, the fire service said.