I assume you are referring to something like the below picture. I custom made those but you can find some on e-bay if you look for stack covers. Scheid has flat top covers, not sure about miter cuts.
A smart man might plumb the stacks so they were weatherproof.
If you place a larger section of pipe somewhere in the system that is between 0 and say 45 degrees off horizontal you form a "bell" and the water pours right out on the ground.
For instance, if the pipe feeding the stack(s) is 4" dia pipe, then at some point under the truck along the path from stack to engine simply have the pipe run through a 4 to 5" transition to about a 1' long section of 5" pipe. This makes a "bell" on the stack side of the junction. The engine side will remain 4" and slip inside this 5" bell on the stack side of the junction.
Now you have a connection that won't cause flow disruption, but will allow water that enters the stack(s) to freely run right out unphased.
A lot of equipment comes this way. Works very well.
A smart man might plumb the stacks so they were weatherproof.
If you place a larger section of pipe somewhere in the system that is between 0 and say 45 degrees off horizontal you form a "bell" and the water pours right out on the ground.
For instance, if the pipe feeding the stack(s) is 4" dia pipe, then at some point under the truck along the path from stack to engine simply have the pipe run through a 4 to 5" transition to about a 1' long section of 5" pipe. This makes a "bell" on the stack side of the junction. The engine side will remain 4" and slip inside this 5" bell on the stack side of the junction.
Now you have a connection that won't cause flow disruption, but will allow water that enters the stack(s) to freely run right out unphased.
A lot of equipment comes this way. Works very well.
I think your missing my point. I don't want water getting into the stack when sitting outside in rain or washing the truck...doing what you said still isn't gonna stop water from getting into the stack.
THATS WHAT I DID ON MY TRUCK, IT HELPS, BUT IT STILL MAKES A MESS