Antique Truck Tractor part? RV463

this looks like a pressure relief valve off of a larger flange system to a fire suppression system for a building for a business... which need to be red for quick identification, these are meant to bust if the pressure in a system gets too high to prevent catastrophic damage. RV*** on the part seems to be a good ID that this is a relief valve

References:

https://www.bing.com/images/search?

Reason:
ok yes, but I need more information about the fitment

Obviously a relief valve (pretty sure this one was adjustable up to 460), and were used on a wide array of applications, from engines, equipment to boilers on ship and shore. I believe the name of the company is/was National?, that is their logo - the N/circle made up of two pipes facing opposite directions. Sorry Im drawing a blank on the name of the company. I immediately recognized the logo. the numbers 460/463 are generally the capacity.

References:

http://www.mylousymemory.com/dontclickthislink.htm

Reason:
thank you for the option, but looking for a fitment