Resilient or metal seated gate valves

[SHOchris]

Is there reason to spec one over the other instead of just life span? The city I am doing work for specs only brass metal seated, but the contractor says that he has never used anything but resilient wedge gate valves...and that they are "better"
I have read up on them some, but dont really see a reason to choose one over the other... either have a better seal, or last longer...


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[rconner]

Resilient-seated gate valves have been used for more than a quarter century. While there are perhaps many aspects to compare, I believe a few advantages of modern resilient-seated valves for example over iron-body bronze mounted (IBBM) gate valves are:

1. Basically a clear and unobstructed waterway, that does not exhibit a bottom potentially debris-trapping “pocket” (like to receive the wedges that hit down in same and in various fashions spread e.g. IBBM disks).
2. Demonstrations that at least some resilient-seated gate valve designs will effectively seal (and even bottle-tight) against at least some significant foreign objects like rocks and steel nails (that will generally thwart metal seals when trapped in the seat area).
3. At least some resilient-seated gate valve designs employ quite strong principal parts of ductile iron only, whereas IBBM gate valves per some standards/designs still can contain weaker gray cast iron.

While I believe “better” is something that should ultimately be defined by the users (including I would think Contractors, as it appears is one party you’re already conversing with, who sometimes are asked to even test against such valves), I believe there has been a dramatic relative increase in demand over many years for resilient-seated as opposed to IBBM valves, and particularly in common municipal fields. [You may be interested e.g. in some perspectives of a very large valve manufacturer (who I know has produced both types for a great many years) reflected now at e.g.

http://www.acipco.com/afc/videos.cfm.

]