What do you think are the relative merits between butterfly and ball valves?
I figure the butterfly valve is easier to clean, but the ball is less likely to get clogged. Anything I’m missing?
I haven’t had any butterfly valves clog. I do use a Bazooka screen inside the kettle though.
for brewing purposes there is not likely to be any significant difference due to the type of valve. the manufacturer specific may have design features that makes one easier to maintain over the other. on a big scale when a ball valve is opened the flow path is clear and there is less pressure drop. the disc in a butterfly valve will remain in the flow path causing a slight pressure drop. i have not read any great throttling features of either but i suspect that a butterfly valve is a little easier to throttle flow as it affects the flow as it affects the flow more around the periphery as the valve is cracked whereas a ball valve only affects one side of the flow path as it is cracked.
Wow, first read that a having something to do with turkeys. I think I need a beer.
butterfly on the cold side, ball on the hot side. Especially if you use whole leaf hops (especially a massive wet/fresh hop beer) without a screen/bags.
Thanks all. I ordered a couple of butterfly valves, mostly for sanitary reasons.
You didn’t study fluid mechanics in the engineering core?
Yes, but that was a long time ago and I’m not worried about the fluid dynamics, just sanitation and blockage. But if there is some factor I haven’t considered I figured someone here would bring it up. 
Ball valves have smooth edges, conducive to one smooth flow path. Butterfly valves have a cutting edge, splitting the flow and providing a catch point surface. Gate valves on the otherhand provide finer tuning…
That’s why butterfly valves are poor for regulating flow from a higher-pressure pump - they tend to wear and leak. I don’t think a March pump would cause issues though.
They do have to be a LOT easier to clean than ball valves. Tom - have you used the new valves yet?
I don’t think you could keep a gate valve clean/sanitary.
How about this for a clog?
That is a 24" butterfly valve that was located just downstream of a sodium hydroxide injection point in a water system. The NaOH was added to control corrosion potential in the distribution system. Unfortunately, the caustic did not mix well in the pipe and it precipitated the deposits in the pipe and on this valve. I would expect that the deposits were calcium carbonate (chalk), but the high OH concentrations actually caused calcium hydroxide (lime) to deposit instead.
This isn’t really applicable to this discussion, but I figured some might enjoy the mysteries of water chemistry (when done wrong).
That is awesome Martin, since the pic lacks scale (but not limescale) it looked to me like a mattress shoved in there
I haven’t used the new valves yet, I ordered them yesterday. But I use butterfly valves on one of the fermenters, just curious if I should get different ones this time - I was thinking it might be nice to have ball valves on the dump ports and butterfly on the racking ports, but decided against it.
Well ya didn’t specify an application, Tom. ::) Guys in the other hobby I enjoy are constantly crowing the virtues of gate valves, but that’s for vapor management. Gate valves tend to be difficult to operate in high liquid pressure/flow locations.
I hope that wasn’t your water system Martin!
I figured on a brewing forum the range of applications would be understood ;D
my thought exactly.
That pictures reminds me of strata along the Colorado river.
Different valves for different jobs. Recirculation, heat exchange, filtering, fluid transfer, trub removal/yeast harvesting, gas pressure control, CIP, keg cleaning…
ugh. brings back old submarine memories. i used a hemostat on some tubing when i was experimenting with a heat exchanger if you look at the bottom you will see it in action
Just one of my clients on the Mississippi River with a really old water system. They have all kinds of problems they are dealing with. They have a lot of old cast iron pipes that are prone to failing in this cold weather. They had a 1.5 MGD leak last week that it took several days to find.
that’s when you call something art and sell it for some more brewing equipment.