Ball valve vs Globe valve for On-Off application

Hi,
Can anyone confirm which one is better option for shutdown applications i.e globe valve or ball valve?
As per my understanding , ball valve act fast as well as economical as compared to globe.
Is leakage across ball valve is more than globe valve?
 
munny07,

The choice really depends on several factors.

1) Service/Application
What kind of fluid (liquid or gaseous)?

2) Speed of closing required for the shutdown application
If you need fast closing action, you need to take this into consideration when choosing an actuator for either a ball- or globe valve.

3) Will you be using an existing or new actuator on this valve?

4) Are you replacing and existing valve, and if so, what type was it?

Globe valves are generally used for flow control, not for fully open/fully closed or shut-off applications (I'm referring to automatic valve control applications). But, I have seen both globe- and ball valves used in shut-down applications, though the globe valves were usually used in applications that didn't require extremely fast closing times and generally had larger actuators which also had to be able to make multiple full turns of the valve stem to close the globe valve, whereas ball valves are usually only quarter-turn valves with simpler, and faster (usually), actuators.

Hope this helps! Again, globe valves are not all that common in industrial applications, and where they are used they are generally manually-operated valves for things like impulse lines and the like.
 
Thanks for your response. I have only used ball valves for shut off applications because it's action is faster and it's more economical. But recently, I have gone through documents of one of the Engineering company and they have used globe valves for shut off applications. They told that leakage rate per inch travel across ball valve is more than globe valve. I am not sure about it. Can you please confirm whether it's true? If yes then any reference document available for the same.
 
munny07,

You didn't mention a requirement for specific leakage rates.... As was mentioned, the application/service the valve(s) will be used in have a very large impact on the choice of valves. And, also, come companies have preferred methods of achieving the desired operating characteristics--sometimes based on experience, sometimes based on preference of the company or the Customers they have worked with before. Some have their own internal standards for these types of things, which may or may not meet local technical regulations and standards or the standards of the plant where they will be installed.

Valve manufacturers produce what are called "data sheets" or "cut sheets" for every valve they produce (or, sometimes, groups of valves). These have quite extensive information about leakage rates, classifications of valves (based on leakage rates. These are almost always available on the World Wide Web at the valve manufacturer's website, and quite often on manufacturer's websites that sell these valves in different parts of the world as well.

This kind of information can be obtained on the World Wide Web using your preferred search engine (you will probably have to go through a few different search terms and words to get the information you're looking for--but you will also probably learn one or three things in the process).

Finally, most manufacturer's representatives--the better ones--will all be familiar with the products they sell and often the requirements of your specific application or needs and can make excellent recommendations. Manufacturer's representatives quite often sell devices and equipment from more than one manufacturer and sometimes sell more than one type of equipment, from multiple manufacturers. (As in any profession, there are also representatives who are just selling devices and will recommend anything--usually the ones that make them the most commission.) So, if your plant has manufacturer's representatives they prefer to deal with and have had success with in the past, call them or have them in to discuss the application and their recommendations. They will either have or send the data sheets/cut sheets for the equipment they recommend or can send you URLs to find them. OR, you can search various valve manufacturers (Fisher, for example) yourself.

Those are your best resources for specific information for your application(s): the World Wide Web, and manufacturer's representatives. I will make these two cautions about them: First, trying to find and specify equipment or devices with little or no experience with the process or the equipment can lead to some disastrous results. I have been to sites (multiple sites) where an engineering firm specified this or that valve or electric motor for a specific application/service, and during and after commissioning there were problems--sometimes serious problems which affected reliability and operations. Several times after some serious investigations and troubleshooting it was determined that the wrong components were chosen by people with little or no experience in choosing them, and that was discovered after extensive talks with manufacturers and manufacturer's representatives. (For example, all electric motors are not the same. Some are specifically designed for certain applications, such as driving large reciprocating compressors. Choosing a motor designed for a large conveyor belt application for use in driving a large centrifugal compressor resulted in the spider of the induction motor rotor cracking severely in several places and causing high vibrations and outages. (By the way, the motor designed to drive the reciprocating compressor was 25% more expensive than the chosen motor--but that cost differential was MORE than lost in the months (more than 24) trying to troubleshoot and understand the problem, not to mention the lost production and revenue. AND, when the proper motor was installed to replace the first one ALL compressor problems disappeared. Asking motor manufacturers or motor manufacturer's representatives would have saved a LOT of money in the long run!)

Second, all manufacturer's representatives are not the same (like all ball valves are not the same, or all globe valves are not the same). Sometimes you have to talk to several to find one or two that you have confidence in and can develop a relationship with. And, my friend, relationships can make or break one's career. they are very important. And, some manufacturer's representatives are people you WANT to have a good relationship with. Others, not so much; they will recommend the first thing that comes to their mind (and usually that makes them the biggest commission. A good manufacturer's representative KNOWS they will sell you more equipment in the long run if they recommend the right components/equipment, even if it's a small sale with little commission for them or profit for their company--and those are the ones who are successful and BUSY and that you WANT to develop a relationship with.

These kinds of forums are good for basic information--when all of the requirements are understood. But when you want specifics on "general" things, it's best to do your own research on the World Wide Web, or if you have a specific need or application to work with a manufacturer or manufacturer's representative.

Best of luck! (In the future, if you have a specific question, it's usually best to lay it out in your initial post and when people have experience with that situation or application they can make recommendations.)
 
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