I bought a "Valve Handbook", at some expense, I think from McGraw-Hill. It did a good job of explaining how a ball valve differs from a gate valve, for example, and it was a help in understanding and using the proper terminology for valves of all kinds, but it was of absolutely zero help in (re)designing ball valves.
... which is what I was attempting to do at that time.
A manufacturer of very small ball valves had made a large number of sweeping changes to their valves under the leadership of a previous engineer. After doing innumerable tolerance stackups and manufacturing capability assessments and measurements and physical tests, I slowly came to the realization that their 'old' design was better in almost every measurable way from their 'new' design.
When I left, The Big Guy was forcing evolution of Yet Another New Design, which was headed for trouble because his manufacturing guys wouldn't tell him that it couldn't be manufactured as he wanted to on the machines that he had already bought for it.
... and he had grown tired of hearing Yet More Bad News from me.
Their latest catalog suggests that the Yet Another New Design valve has been made to work well enough for sale, but you can't tell from outside how much pain was/is involved.
My advice: Listen politely to whatever the local experts and manufacturing people have to say. Do not argue with them. Measure everything. Try to understand the science underneath whatever assertions are made, especially the bizarre ones. Make changes a little at a time, keep measuring everything, keep detailed records, and be honest with yourself.
Mike Halloran
Pembroke Pines, FL, USA