Ball Valve Flow Direction 2

[Boynt]

Does the direction of flow through a V-ball type ball valve vary from manufacture to manufacture? I have gotten two different answers on flow direction from different companies, so now I am questioning my understanding. When the ball valve is closed, should the flow be hitting the concave portion of the ball or the convex?


Barb

http://www.Exlar.com

Best alternative to hydraulic and pneumatic actuation

The only way to make someone trustworthy is to trust them.

 

[pennpiper]

Boynt,
As a suggestion I think it would be best if you took a look at a real "Ball" valve.
Go here -(

https://www.google.com/search?q=Bal...zC4uq8ASv24CwBg&ved=0CC0QsAQ&biw=1024&bih=665

)
You will see images (Drawings and Photos) of Ball valves. You will also see that no matter which end of the valve you look into they both look the same.

prognosis: Lead or Lag

 

[Boynt]

pennpiper,
I am referring to a V-port ball valve. I have always assumed the flow is against the convex portion when closed as in this diagram, but I had a manufacture rep tell me otherwise. I want to make sure I understand it correctly.


Barb

http://www.Exlar.com

Best alternative to hydraulic and pneumatic actuation

The only way to make someone trustworthy is to trust them.

 

[tr1ntx]

depends on the seat design, I suppose

 

[gerhardl]

A 'normal' V-port ballvalve will have (as drawings sent in from others indicate) a preferred flow direction, indicated by an arrow, normally cast int the house. Please bear in mind that a V-port ball-valve has no full-bodied ball, but rather most often a shell, often not completly 360 degrees formed, and in addition with the V-notch as opening. The opening goes from shut valve through small to large part of the V exposed.

The preferred flow direction is, as far as I have seen, in all cases from 'inside' the body (against concave innerside of shell/ball) and out through the regulating V, and into the downstream pipeline. Several reasons:

-For especially floating ball/shell construction (and partly also trunnion mounted) this flow direction will help sealing by pressing ball/shell against the seat sealing.
- For regulating purposes this will send flow out into a straight pipeline, instead into a more irregular formed body, helping forming laminar in stead of turbulent flow.
- A V-port ball valve is constructed to regulate flow in a rather wide range, strengthening the reason for a straight pipeline some valvelengths after the valve.
- Also for distance and placing of flow measurement will soonest possible laminar flow contribute.

 

[donf]

Boynt,

I've received the same responses. Different direction from different manufacturers. Haven't had the opportunity to learn why.

Please let us know if you find out the reasoning.

donf

 

[PeterIgg]

I suggest that it will relate to the construction of the valve. In general (and there are exceptions) trunnion mounted valves seal on the upstream seat, therefore the profiled seat would have to be on the upstream side. Conversely floating ball valves will seal on the downstream seat, therefore the profiled seat would have to be on the downstream side for that construction.
If the valve is used in the reverse direction of flow it is likely that the flow will push the seat off the ball and therefore affect the effective orifice area created. In one brand that I am aware of, using the valve in the reverse direction can irreparably damage the seat, so be sure to use the I O & M that should come with the valve to avoid any unpleasentness! If in doubt ask the manufacturer, it will protect your warranty if nothing else.

 

[zdas04]

Every notched ball control valve I've ever seen has had an arrow cast into the body and the arrow put the upstream pressure into the concave portion of the ball (i.e., the seating surface is on the downstream side of the valve. Control valves in general and V-Ball valves in particular are not bi-directional and need to have the arrow on the body.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[DRWeig]

The brand we used to sell are like zdas04 says. Flow into the concave portion, seat and spherical portion downstream.

Best to you,

Goober Dave

Haven't see the forum policies? Do so now: Forum Policies

 

[Boynt]

OK, I have researched several valve manufacturers on the web, and found that many do not do a good job of defining what direction the ball should be in for closing. Fisher does specifically say:

Standard Flow Direction
Forward (into the convex sealing face of the ball)

This is what I assumed to be the standard. It is how I have been mounting my actuators for control. (See link with flow arrow)
This appears to contradict what many have posted here such as
Every notched ball control valve I've ever seen has had an arrow cast into the body and the arrow put the upstream pressure into the concave portion of the ball
Any manufacturers want to comment? Looks like I need to call you prior to each install.


Barb

http://www.Exlar.com

Best alternative to hydraulic and pneumatic actuation

 

[bcd]

For V-balls, flow direction depends upon the seat type and what service the valves is being used in. Even Fisher has special versions where flow should go opposite what you say is their "standard". Same is true for Neles. Both directions are possible. Depends upon the seat type and desired shut-off tightness.

Now to generalize, th majority of V-ball type control valves, the valve has a spring loaded seat which presses it into the ball, and the flow is intended to come from seat side flow port (convex sid of ball). More often than not, that is what you will encounter. But, like very rule, there are exceptions, like abrasive services with fixed (not spring loaded seats).

 

[hsbcn]

Most (respectable) manufacturers will stamp the appropriate flow-direction, if one is oreferred, on the valve body, and also diagram-guide the user in the IOM. To be honest, I wouldn't opt to follow any generic advice, but would rather turn to the manufacturer of the valve I'm dealing with and get the word from the horse's mouth.

My focus is on petrochemical valves for corrosive applications.

 

[chicopee]

Intuitively, I suspect the concave side to be stronger than the convex side; so if you closed the valve too quickly and developed a surging load, the concave side will be able to take on the additional load whereas the convex side may get "punched" out.

 

[ballvalve02]

When the ball valve is closed, should the flow be hitting the concave portion of the ball ! half ball not Integral V-ball type