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Join Date: Nov 2008
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control valve Classification According to Port Size

11/30/2008 8:03 AM

what is the different between Full-Port Valves and Reduced-Port Valves?

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Anonymous Poster
#1

Re: control valve Classification According to Port Size

11/30/2008 11:36 AM

Full port valves have the opening the same size as the nominal pipe bore. They are more expensive than regular (reduced) port valves but offer better flow characteristics/less pressure drop and are generally required if pigging of the pipes is to be done. They are also generally required for the inlets to pressure relief devices, and if any type of instrument/sampler are to be installed through the valve opening.

Reduced port valves' openings are smaller than the nominal inside diameter of the pipe. They are cheaper, but have more pressure drop and generally aren't used for pigging.

There are no technical reasons to use a reduced (regular) port valve - only economic reasons.

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Anonymous Poster
#3
In reply to #1

Re: control valve Classification According to Port Size

11/30/2008 9:54 PM

.......... oh yeah - another reason for full-port valves is when you are performing a hot-tap.

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Active Contributor

Join Date: Aug 2008
Posts: 19
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#2

Re: control valve Classification According to Port Size

11/30/2008 11:50 AM

FULL PORTS (the valve's port opening is the same full ID dimension as the pipe size )

Reducer valveare designed to reduce pressure of an incoming line that is operating at too high a pressure. Factory set to reduce an

incoming pressure down to 45 psi ( for household use ). Maximum incoming pressure upto 400 psi and delivery pressure range of 10 to 70 psi.

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#4

Re: control valve Classification According to Port Size

11/30/2008 10:55 PM

On a control valve the meaning of reduced port and full port is a whole different matter than on-off valve, where full port means the same size of line and reduced port is used as an economic option.

The use of a full port or reduced port on a control valve depends of

- Cv calculation

- Flow characteristic

- Relationship between line size and valve body size.

My reccomendation: as you send complete ISA Spec Sheet, leave it to valve manufacturer the selection of best internal diameter to use.

David L V Rodrigues

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#5

Re: control valve Classification According to Port Size

12/01/2008 4:11 AM

For ESD apps customary to use Full Port

Regards

Jose

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#6

Re: control valve Classification According to Port Size

12/01/2008 10:10 PM

Without going into the a discussion of some of the more exotic valves that have been created by man and sticking to the one of the most simple valves, the BALL VALVE (With the assumption that by a "control valve" you mean a valve that is controlling flow, which is what every valve that I have seen does): as stated previously by some of the postings a full port ball valve is one which has an inside diameter of the hole through the ball at the same diameter as the inside diameter of the pipes that are intended to be connected to it. (excluding the use of heavier wall pipe such as Schedule 80, 160, etc.)

A regular port ball valve has a hole i.d. smaller than the intended pipe, therefore causing a restriction to flow in the piping.

More and more ball valves are being made as the full-port type being the standard. Likewise the percentage of valves being made with regular ports (smaller than the i.d. of the piping) is getting smaller and smaller.

An old-time chem eng. and several very intelligent pipe fitters have told me that the older regular port ball valves were made that way because of the strength of materials used in their manufacture. As alloys became stronger and manufacturers became more confident in them, the bore was increased to accomodate the need for less flow constriction. (old-time chem engrs and smart pipefitters are the best wealth of knowledge for piping questions and problems). The past normal materials of construction were: brass body, chrome plated brass ball with teflon seals between the ball and the body, and either string or teflon stem packing. Now the bodies are usually bronze, balls are of stainless steel, virgin teflon ball seals and solid teflon stem packing. About the only thing that hasn't changed is the steel handle.

Good luck,

a growing old chem eng who has done more pipe fitting than he can remember

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Anonymous Poster
#7
In reply to #6

Re: control valve Classification According to Port Size

01/01/2009 11:23 PM

Also the higher permissible velocity of the fluid through Valve forging compared to the pipe line makes the port size smaller (reduced port). Full port are used where there is a very high differential pressure across the control valve orifice especially during an unsteady flow condition. In this case, reduced port may lead to cavitation, Flashing and Sound. Full port is preferred.

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Ali Zude (1); Anonymous Poster (3); David Rodrigues (1); josej (1); old salt (1)

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