That big red thing toward the firewall looks like some kind of float device, similar to a boiler low water cutoff. If you can read the patent numbers on the side of it, try a search
here. You may come up with something that will tell you it's purpose. I tried, but can't read those patent numbers very well and tried quite a few possibilities. It looks like it's tying the fire pump to the engine cooling system to me. That's a lot of plumbing.
[on edit] On second look that long grey thing on the fender is likely a heat exchanger, used to supplement engine cooling from the water pumped thru the fire pump. Many stationary engine driven fire pumps use that type of system for engine cooling instead of a radiator. and running the engine at high RPM's to run the fire pump would kind of stress a radiator only cooling system.
