Does anyone know what the really old commercial exhaust hoods were like? I saw an episode of Matlock once, that was supposed to take place in the 1960s (though the episode was from 1993) and there was a restaurant in the episode with what looked like an old hood. It was curved at the top and kind of curved back to the wall IIRC. In a way it reminded me of a Vent A Hood but bigger and stainless steel. It had the fire sprinkler nozzles underneath.
I have never really seen any all that old with how often restaurants change and remodel. But I may have seen some old ones and didn't know it. I think I heard the old ones had aluminum mesh filters, but they changed to the slotted style filters. Also the old hoods didn't have fire sprinklers under them. I'm pretty sure I've seen some old exhaust fans on the roofs of restaurants that could well be a few decades old.
I'm not sure any of the old hoods could still be in use, I doubt they would meet the fire code. I know some of the schools here still have the original hoods from 1979-80 in them, but they look pretty much like the newer ones.
I remember the one in my high school was really long, and on the vertical faces of it, there were vent grilles that returned air to the kitchen to replace the air that was sucked out. It's still there, in use, although the rooftop units were replaced about 10 years ago.