valves

N

nmaho

New member
whats the difference between a ball valve and a gate valve, will probbally have to use one on return pump
 
Basic explanation
A ball valve has a ball that closes - by use of a large paddle lever. A gate valve is more accurate (in smaller increnets of shutting the valve), uses a handle similar to what you see on an outside water shutoff.
 
For a one-line schematic:

Ball valve: -----|o|-----
Gate valve: -----|><|-----

Seriously, it depends on the size and application. If anyone really wants a detailed explaination on the difference in hydraulic charectaristics between the two, I can try and give one.

I have not heard of a gate valve being used on a reef tank. For the size and application, I would only consider a ball or globe valve,

Matt:cool:
 
I'm not sure there is a better or worse, it all depends on your application. A gate valve will give you finer control of restricting water flow. If there is a buildup of calcium or other things on the gate part of the valve, it may not close all the way (gate valves close top to bottom.) A ball valve, while not allowing you to adjust in very small amounts, should clear away the deposits as it closes, since it closes side to side.

Jeff
 
I use both on my system. The ball valve I use for on-off situations - like for emergency cut-off. The gate valve I use on my return pump to regulate the flow.

I think they both have their usages, but are not interchangeable.
 
Sea Serpent said:
I use both on my system. The ball valve I use for on-off situations - like for emergency cut-off. The gate valve I use on my return pump to regulate the flow.

I think they both have their usages, but are not interchangeable.
Click to expand...

Same here. I bought mine at HD or Lowes. I wouldn't expect a gate valve to completely seal (close) air tight. Although I do know lots of people use ball valves to adjust flow, they do work, it was not their intended use.
 
Although I do know lots of people use ball valves to adjust flow, they do work, it was not their intended use.
Click to expand...
Actually, for industrial use, ball valves are frequently used to modulate flow for small diameter lines (say 6 in. or less), while butterfly valves are used to modulate flow for large diameter lines (8 in. or greater). Ball valves and butterfly valves have the optimal tradeoff between modulation capacity and cost.

Both ball valves and butterfly valves have a very linear relationship between a coefficient called Cv, which translates roughly to head loss across the valve, and degree of modulation (percent open). Moreover, they are relatively less expensive when compared to eccentric plug valves, gate valves, etc.

I was unable to find comparative graphs to demonstrate this, but you can click here to read more about what they refer to as linear output. You can never get linear output near the valve position extremes, but the more linear your Cv curve is, the greater the ability of your valve to modulate flow.

But somehow all this doesn't translate to reef tanks, where the practices of the field are turned on their head. Here, ball valves are used for on/off applications while the gate valve is used for modulationg flow. Oh well. What can a (former) engineer do?

Matt:cool:
 
I stand corrected. As Matt usually makes me go back and research my answers (students can be annoying). I found I was wrong. I didn't find any "official policy" but I did find lots of links that state gate valves are not used to control flow. For the geeks out there, I found these descriptions easy to understand: http://www.dep.state.pa.us/dep/depu...ormulas/Pages/valvebasicsandselectiontips.htm

Let me just sum up why "I" use gate valves to control flow. It takes several turns to go from fully open to fully closed. I find it easier to do small flow adjustments with gate valves rather than ball valves.

Matt,
Please don't pick on my grammer. I know that I know nothing about it. :)
 
The ball valves I used for my new system were very expensive and came from Aquatic Ecosystems. The handles are better to work with and they are also true unions. I have them placed as emergency shut offs for the 5 bulkheads for the closed loops.

True Union Ball Valve

I also got gate valves from them . .. a little more expensive, but they have hard-to-find stuff. Good customer service, fast shipping and they take stuff back if you don't use it . ..
 
Sorry

Sorry

Matt,
Please don't pick on my grammar. I know that I know nothing about it.
Click to expand...
Groove,

I'm sorry. I didn't mean to pick on anyone's grammar here...:( I think this is a great thread and a great discussion.

While I was posting a response to educate, I think what is really important here is what reefers use and have good experience with, and not necessarily what is in the outside world.

Still, you wouldn't want to be out at a dinner party, and start expounding on how gate valves are superior for control in the presence of a bunch of hydraulic engineers. That would be really embarrassing,

Matt:cool:
 
jimmyj7090 said:
damm it!!

I'm going to dinner with a bunch of hydraulic engineers tonight and I thought I could impress them.

j/k matt
Click to expand...

OK, then make sure you tell them they should use a globe valve to regulate flow. :)

Matt,
I am kidding. It's hard to see if someone is joking if you can't see them smile. :)

I appreciate your feedback. Also, since I haven't been out of school very long, your viewpoint brings me back to where I was when I was studying ME at UMass Lowell.

The grammer joke was from a previous thread about a month ago if you remember it... not important. Only trying to have a little fun. :D
 
Engineers don't know how to have fun. They are to worried about their coefficient called Cv.
Click to expand...
That about says it all. Cv is a beutiful thing, by the way.

To the optimist, the glass is half full. To the pessimist, the glass is half empty. To the engineer, the galss is twice as big as it needs to be,

Matt:cool:
 
Not only twice the size it needs to be but made of inferior glass. We need crizzy cups with diamonds and flashing lights.


Why i bump old thread i find in search. I have no idea sry
 
You must log in or register to reply here.

Similar threads

DjPhato
Fluctuating water level in overflow compartment
Replies
6
Views
142
kharmaguru
kharmaguru
DjPhato
Overflow - best option for 90gallon
Replies
7
Views
233
DjPhato
DjPhato
Z
Old Elos 70 - how to raise water level and reduce water noise?
Replies
9
Views
189
discotu
discotu
A
Dual overflows 2 full siphon, 1 emergency, 1 return
Replies
1
Views
171
Vinny Kreyling
Vinny Kreyling
Jyetman
UNS Aquariums Good or Bad
Replies
1
Views
253
lvanderbeck
L
Back
Top