Valve Port Terminology Clarification

[CW3]

I have a customer that has a piping specification that refers to ball valves as "regular port" and "full port". Now, I'm very clear, when referring to "full port", as to what I'm referring to. On the other hand, when someone refers to a ball valve as "regular port", what specifically are we refering to? I'm fairly sure I know, but I want to see what the general concensus is. This may sound picky or silly, but it's important to me at the moment.

Thanks,

CW

 

[Ashereng]

Regular port means reduced port.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[11echo]

CW3 ...When you order a ball valve without specifying a port size, you will get a 3/4 port valve. This is the "regular port" size the ball valve comes in. Only when you order a "full port" for flow and or for hot tapping is when you get the 100% open port valve. Good Luck! ...Mark

 

[Ashereng]

CW3,

Here is the specs for a Durco ball valve. It shows the size and Cv of full and regular ports.

http://www.flowserve.com/vgnfiles/Files/Literature/Products/Flowcontrol/Durco/dvatb0060.pdf

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[BigInch]

Its not picky or silly to me at all. YOU NEED TO KNOW what you're selling. Especially if you or your company want to stay in that business for very long.

I'm curious. Are you getting any training? Isn't there anybody at your company from who you can get important information like this from? What's the rest of the story?

http://virtualpipeline.spaces.msn.com

 

[joeswoes]

MSS SP-72 "Ball Valves Flanged or Butt Welding Ends for General Service" " is the reference you need for this question.

 

[JimCasey]

Regular port means that the hole in the ball is a size smaller than the pipe size of the body. 10" body: 8" port.

Although this shows up as a reduced Cv, in actuality the "regular Port" Cv is so large you'd be hard pressed to measure a pressure drop at flowrates that won't be so high as to erode the pipe. Full Port Cv values are also published but I have always contended the Full Port Cv should be infinite, as a full-port valve has the same restriction as an equivalent length of straight pipe. Sometimes, due to the better surface finish inside the ball than inside the pipe, the valve actually has LESS pressure drop than an equivalent length of pipe.

Unless you need to pig the line or pass some sort of probe through the valve, a regular port valve will serve well, and it is more economical: lower purchase price, and lower torque required to turn the smaller ball probably saves you a pile of money on the actuator.

 

[BigInch]

I like the idea of infinite Cv coefficients, but that would also mean infinite flow would be possible. In all seriousness, I need Cv's for both full and reduced port valves vs %open, which of course even for full port is not always [∞]

http://virtualpipeline.spaces.msn.com

 

[Ashereng]

Most valve manufacturer have tables of Cv vs. %OPen available in graduations of either 10% or 25%.

Just a note, flow through a piece of pipe is not infinite Cv, there is still a number as there is still pressure drop. Granted, it is a very large number.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[BigInch]

Ya, I've got most of the majors already coded up. Guess I should have put a smiley with that. Hey, sorry I wasted your time making you say something about that Ashereng.

http://virtualpipeline.spaces.msn.com

 

[JimCasey]

I'm NOT going on a crusade about this but I will offer an explanation about my infinite Cv comment:
The valve contributes no loss to the system. THe system loss is the same whether the valve is open or if there is a spoolpiece there instead of the valve. Therefore the DP atributable to the valve is Zero, which implies infinite Cv. Cv= Q*Sqrt (sg/DP), so you're dividing by zero. In third-decimal-place context is the little disruption you have at the seat ring and the radiused edge of the ball. Does it really matter since it lives in the boundary layer? Not a lot. It's gonna be a helluva lot less (theoretical)disruption than a full-port Gate valve. Practically, the pressure loss may be 0.0002 for the ball valve and 0.002 [units intentionally omitted]for the gate. Somebody might freak out that the gate has 10x the lost pressure but in reality both pressure drops are so low as to be meaningless in other than academic considerations.

Full-bore valves also are not properly used for throttling, so Cv curves for a full-bore valve are pretty-well meaningless. Size a full-port ball valve for system velocity just like you do the pipe, and use it for on-off service only.

 

[BigInch]

All I can say (or want to) is when you deal in miliseconds, the number 0.001 is very important.

http://virtualpipeline.spaces.msn.com

 

[FredRosse]

Jim Casey wrote:

"The valve contributes no loss to the system. THe system loss is the same whether the valve is open or if there is a spoolpiece there instead of the valve. Therefore the DP atributable to the valve is Zero, which implies infinite Cv. Cv= Q*Sqrt (sg/DP), so you're dividing by zero."

I must disagree with this statement, the proper conclusion is as follows:

The valve contributes loss to the system the same as a spoolpiece. THe system loss is the same whether the valve is open or if there is a spoolpiece there instead of the valve. Therefore the DP atributable to the valve is the same as a spoolpiece, and the spoolpiece has friction, generally equal to f * L / D. Therefore the DP atributable to the valve is non-Zero, which implies a finite Cv.

 

[jte]

Folks-

Would you agree with Jim Casey if the statement was amended to read:

"The valve contributes no additional loss to the system beyond that attributable to a spool piece..."

jt

 

[MARKFLOW]

Full Port is "true full", and can be a relative term based on the I.D. of your Pipe (Schedule of your pipe).

Regular Port, or Standard Port is one pipe size down.

Reduced Port is (2) pipe sizes down.

MARKFLOW

 

[RR05]

There are actually three versions of port size:
Regular port- when ball valves came out, this was the standard port size which was, as said in other strings, 1 port size smaller than the line size.
Full port- as logic has it, a full line size according to sch 40 pipe. Note, a full port valve is not full line size if you are talking sch 10 pipe- can cause pigging problems.
Reduced port- this was a way to drive costs down further in valves and is actually a port size smaller than regular port valves. Not seen very often now, but was more prevalent in the 70's!