4 replies to this topic

[Marco78]

I'm studying some specifications for ball valves; among the usual ones I already know, I found a new one in which I don't understand two characteristics:

- Venturi bore (pattern)
- Floating ball

what are the advantages/disadvantages of these two features?
Thank you very much
Marco

[Zauberberg]

A "Venturi bore valve" means nothing more than reduced-port valve, i.e. the valve in which the flow area is reduced - when compared against the pipe ID.

Floating ball valves have improved sealing characteristics (quoting from the manufacturer catalog): "The ball has some freedom to move along the axis of the valve while having no freedom to rotate against the stem. When line pressure is applied to the closed ball, it moves slightly (or floats) downstream to maintain contact with the downstream seat where primary sealing occurs."

[ankur2061]

Marco78,

To know about the types and the function of ball valve have a look at the following link:

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

Regards,
Ankur.

[Marco78]

Thank you! You are very kind.
If for the floated ball valve now is clear the advantage actually I don't understand why install a venturi bore valve (or reduced bore) instead of a full bore valve. In fact the specification I have is very general and it is not referring to a particular process condition: is it maybe about economic aspect?

[Zauberberg]

Yes, reduced-trim valves are much (much) cheaper - the cost ratio can go up to 3:1 or 5:1, when compared against full-bore valves. In general, if you are not so much concerned about the pressure drop (because you usually employ ball valves in on/off or isolation service), and if there are no process requirements for full-bore valves (e.g. pigging - those lines must NOT have reduced-port valves), you normally opt for a venturi or, in simple words, reduced-bore valve.