Similiar to Mark's Butterfly Valve Question

pfitter_2

A few years ago, I would have agreed with you. The butterflies were poor. But there have been vast improvements in them that are impressive. You didn’t say, what type of system are they on and what flows through them. Being rubber seated, they must be spec'd for the proper service. I have no qualms putting in the better brands available. Groovelok, Grinnell, Hammond. I do not like the wafer style, for the reasons you point out; I see no good propose for them. The pros are Lighter weight, cheaper, easer install, take up less room. When properly spec'd, I see no cons. Sure, nothing beats a good quality gate, but the cost difference alone is worth the switch. Do you have a maintenance program that requires each and every valve to be worked at least once every couple of months? Gate, butterfly or ball, all valves need to be worked to ensure they will be workable when you need them.

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canuckDale

Help - butterfly valves

This is similiar to Mark's post, but I need more experience/pros & cons on the valves only.

Having a difference of opinion with an engineer. Our spec CLEARLY says - No butterfly valves. He messed up, didn't check our spec or his own company/job spec and said yes to the mechanical contractor . Now he (Eng) faces a $20,000 change out. Respectable engineering firm and they will eat it in the end. But of course, I hear all the wonderful things about newly designed butterflys. Granted, technology has changed. The reason we don't allow them is that we maintain our school buildings into perpetuity and have had the experience that when you need an isolation valve, those butterflies won't shut off. With gates and balls that won't completely shut off, at least you can break one flange, install a "pancake", make the repair and change the valve another day. The bolts of course run right through the butterflys, flange to flange, and you can't do that.

I'll take all opinions. Maybe I need to get into the 21st century?

Thanks

Dale

Aidan (UK)

butterfly valves

I first specified butterfly valves in 1996, in 4" and 6" sizes for boiler isolation, with manual and motorized operation. I'd found the usual gate valves tended to let-by. I've no regrets, the butterfly valves still give a tight shut-off, but it's early days yet.

Wafer type buterfly valves are clamped between flanges, but most manufacturers offer lugged types which are suitable for end-of-line use, but are more expensive.

I think I'd always prefer a large butterfly over a gate valve.