Ball Valves versus other types of valves

My application field is water and therefore reply might not be applicable to other fluids or gasses.

Advantages.

Quick action (1/4 turn from open to closes)

Almost no restriction when opened. it is seen as a short piece of pipe by the water.

A good seal can be obtained.

Resistance to abrasive flow. ie sand in water - does not come into contact with the sealing part.

Disadvantage

Can introduce water hammer. if opened and closed to fast.

Can be pricey on bigger diameters.

HI,

One of the advantages of ball valves is thier service life is longer than gate valves or butterfly valves. IN past experience at San Francisco Airport, we had a lot of trouble with Gate Valves and Butterfly valves that were over 20 years old, working on the fuel system there. WE did not experience any ball valve leakage or any plug valve leakage.

Rick

Except above,

parts is less,

Easy to manufacture,

suitable mass peodution,

Production cost is lower.

Stainless steel ball and nylon or some other plastic seat....simple indication if open or closed..inexpensive in smaller sizes....etc etc etc

Cause all the stuff these guys said is very true...And because a nice ball valve is just sweet as hell to look at! Honestly...pick one up and play with it a little. What a great peice of engineering work.

Oh yeah, and you can crack your knuckles (or break your fingers off) in a vavle big enough...

Adding to the others comments, when using ball valve which is for quick open and close, be carefull not to use the ball valve where the sudden fluid flow change causes water-hammer or may causes air entrapment in the system. so it is usually used in fluids which need quick response especially gases.

As between gate valves and balls and kindred types, Gates, by design, are full-on/full-full off. Balls (without much precision) and globes are suited for intermediate flow rate setting--without leaking. The reason gates leak out the top when used (other than temporarily) as flow-rate-adjusting valves is that the gate's valve stem is wrapped with packing; the stem must be backed out to max limit (full-open flow) in order to compress the packing against inside of bonnet and block water flow out around the stem. This is an essential answer to your question about valve selection. Most applications in which gates are in gate-open use permanently are applications calling for maximum water supply availability (via down stream valves which are never gate valves) on demand--such as washing machine hose bibs. So, in this sense, gates are best suited as supply valves, and generally utilized that way. When downstream (secondary) flow rate must be permanently user adjustable, select a non-gate type valve. Balls, although least costly, can tend to be the least durable of adjustable valves however, so consider the application and select the best suited valve.

Guest this is a good valve primer

thanks

Heita Member
Join Date: Mar 2007 Posts: 6 #7
Re: Ball Valves versus other types of valves 05/15/2007 2:00 AM

Hi there

As for ball valves... well...

Ball valves are durable. They have perfect shutoffs even after a long time of disuse. They are usually preferred to globe valves and gate valves for shutoff applications. However they do not offer the fine control in throttling applications even though they are sometimes used in this purpose.

Heita

Heita,

Thanks for the response; and, yes, I should not have overgeneralized. But, in one sense, we both are correct - that sense being: the application (requirements) in which a ball valve would be used, the fluid, and the valve's design-for-durability aspect - most especially fabrication materials selection. In considering durability, maintainability must also be taken into account; and it would be true to say that ball valves are maintainable only by replacement. With this in mind, it is not difficult to find balls of such manufacture so as to need (seemingly) unduly frequent replacement (repurchase): household/lawn-&-garden ball valves come to mind, including inline cutoffs and also specialized, path selector types such as wye's and manifolds. On the one hand, such valves when fabricated with plastic are corrosion resistant but can fail (can be damaged by sunlight, erosion, or waterborne particulates...abuse) often enough so as to be deemed virtually "seasonally" disposable (as is probably intended by mfrs). At a higher price, iron/zinc (or partial zinc) fabrication mitigates...somewhat, but is readily corroded. Inherent in these and other examples, would also be, how the ball valve's reliability is affected by frequency of operation--a factor which must be weighed, among other requirements, against maintainability. So, where it might be said that a ball valve, albeit unrepairable, is highy durable, it would frequently be the case that that valve was "durable" only by virtual of its being infrequently operated--perhaps as infrequently, say, as 40 - 50 times or less--during its lifetime; as might be the case, for example, in a household burner supply (fluid fuel) shutoff cock. And even in that and similar instances, one could not always be sure with certainty that flow was "utterly" inpeded--that there was never even a scant degree of bleed through around the ball; in which case (where, say, a hazard was involved) a failsafe would be employed in the form of downstream valving. So, redundancy of function is also a factor, aside from durability-maintainability tradeoff, which needs to be taken into account during the design (for criticality of function) stage.

I have used ball valves, which had replaceable balls, seat seals etc and this was 30 years ago. Yes they were not 1/2" valves, but they were only 6" valves. Contuining the valve "balls" were teflon coated (30 years since), the O seals used were "VITON", ring some bells? and normally had to be replaced every 12 months or so.

Hi there

As for ball valves... well...

Ball valves are durable. They have perfect shutoffs even after a long time of disuse. They are usually preferred to globe valves and gate valves for shutoff applications. However they do not offer the fine control in throttling applications even though they are sometimes used in this purpose.

Heita

<even though they are sometimes used in this purpose.>

Yes .You CanThrottle. Better at low Differential Pressures.

WIN WIN situation.

You can wipe out(99%) of all other type of valves if Ball vaves are made readily available in the Economy.

I would be disagree, I don't think you want to use a ball valve for throttling even a low differentials. My experience is with high pressure drops in the oil field and ball valve are good shut off valves but will want to stay open under high flows or high pressure drops and can be difficult to close. If you try to throttle them you can errode the ball and cause it to leak. As metioned earlier, there is no pressure on the stem so they don't leak out of the packing.

Heita,

Indentured your post and responded. Please see, above (in indentured-thread board format setting); or guest post #16.

Guest

Heita,

Indentured your post and responded. Please see, above (in indentured-thread board format setting); or guest post #16.

Guest

Hetia,

Indentured your post and responded. Please see above (in indentured format board setting) or Guest post #16.

Ignore copies of this below. Did not at first realize that this response could not be done by copy and paste, only be typing directly.

http://en.wikipedia.org/wiki/Globe_valve

http://en.wikipedia.org/wiki/Ball_valve

http://en.wikipedia.org/wiki/Gate_valve

http://en.wikipedia.org/wiki/Butterfly_valve

the point being is that you can search wikipedia, using the term "valve" and get good explanations of as many types of valves as have been submitted.

"Why use Ball Valves instead of others."

NO PACKING to LEAK, ADJUST, and/or REPLACE!

The messages on Ball Valve applications were excellent.I always enjoy getting many different opinions.Thank you all for your replies.What agreat site!

One could say CR4 is on the ball!

Ball valves can not be used instead of others at all cases. For example, in piping systems, the bypass valve in control circuits is recommended to be a globe valve, because the function of the globe valve (throttling & controlling) is similar to the function of control valve, due to the similarity of flow around the disc of the valve.

This may be outdated, but as I understand it, certain valves need to be disassembled (I think it was a the gate valve) prior to soldering it into a system in order prevent melting gaskets or such. Just something to consider to when installing (hopefully I save someone some trouble in their next plumbing venture).

Not outdated, but wrong valve.

Unless the ball valve has a teflon seat (good to about 650 F (350 C) where it begins to gel) it is best to use a three-part ball valve (core is bolted between flanged nipples that get sweat-connected to piping) and remove the core when you sweat the joints. OR you can wrap a saturated rag around the core of the valve during the connection.

Another point about ball vs. gate- if there is ANY chance of dirt, scale, sludge, etc. in the solution being controlled, you MUST install a gate valve with the stem pointing down (to keep material from getting in the seating area at the "bottom" of the valve. Even mounting horizontal allows material to get in track, and eventually in seat area, preventing a positive seating and tight close-off. As earlier noted, ball valves have none of these risks- BUT you should definitely use "full-port" valves. They cost more so MUST be specified or the lesser cost "reduced port" valves will be installed (with some risk of fouling or material build-up and definitely pronounced pressure drop- it is essentially an orifice that you can close.