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Types of valves and their usage?

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Types of valves and their usage?

Types of valves and their usage?

Stuarttait

(Mechanical)

(OP)

20 Jul 02 11:45

Is there a general rule as to when we would use a gate valve as opposed to a butterfly/wafer valve, and same for globe/ball valves and diaphram valves? I appreciate that the material of any type will change depending on the product passing through but are there general guidelines or rules of thumb whereby we would choose one of the four types of valves mentioned (and any other more esoteric type of valve?

Thanks in anticipation?

Replies continue below

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RE: Types of valves and their usage?

zdas04

(Mechanical)

21 Jul 02 18:12

Stuart,
There was a thread  called "Use of Plug Valves" a few days ago that addressed much of this.  

The bottom line is several rules of thumb:  (1) if a ball valve will work with your temperatures and fluids, it is generally a good choice for on/off operation; (2) Gate valves have a place, but it is usually in on/off service in steam operations where you aren't looking for bubble-tight seals; (3) try not to put an on/off valve design where you will want to throttle; and (4) throttle valves come in a multitude of designs and you will want to take a large dose of cavet emptor before believing valve salesmen (one size really does not fit all).  Globe valves have a long history and a definite place, vee-balls are good in moderate temps, diaphram valves have good linearity, etc.

I don't use many butterfly valves any more because I've had a few really bad experiences of trying to dig a broken disk out of piping, but many people have had very good luck with them in a lot of different service.  The valve manufacturers claim decent throttlng characteristics, but my experience has been that they pass a lot of flow very early in the valve travel.

Finally, no one in that thread (and no one I've talked to elsewhere) would purposely install a plug valve in any service.

Hope this helps.

David

RE: Types of valves and their usage?

hero123

(Petroleum)

24 Jul 02 03:15

gate valves are straight thru flow valves which provide positive shut-off with minimal drop and flow turbulence. gate valves may be installed without consideration for the direction of flow. They are frequently used for isolation purpose and when sealings in both the directions are required. They shall not be used in a partially open, throttling position as erosion, noise and excessive wear can occur.
Globe valves are primarily used in applications wherea moderate control or regulation of flow is required. it's recommended to be used in the bypass line of a pressure or flow control valve.
Swing check valves are single direction flow valves used to allow unlimited flow in one direction and retain flow in the opposite direction. They are staight thru valve that work automatically. They can also be used in vertical line where the flow is upward under the disc.
Ball valves are straight thru valves which provide positive shut-off with no pressure drop or flow turbulence. They may be installed without consideration of direction of flow. They are receommended to be used in an open or close position only.

Additional reading:
How to Turn Off Your Water
Key Questions to Ask When Ordering Coffee at a New Café

Goto Yaxing Valve to know more.

RE: Types of valves and their usage?

guest

(visitor)

24 Jul 02 11:18

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RE: Types of valves and their usage?

ralphsare

(Structural)

25 Jul 02 07:28

posted by zdas04
The bottom line is several rules of thumb:  (1) if a ball valve will work with your temperatures and fluids, it is generally a good choice for on/off operation;

ball valves have an equal percentage flow characterisitcs and are therefore suited for control applications.
____
Finally, no one in that thread (and no one I've talked to elsewhere) would purposely install a plug valve in any service.

we do. size range from 3 to 6 inch. gear operated. service - general hydrocarbon, fuel gas, contaminated water, tec.
_______________________-
posted by hero123
gate valves may be installed without consideration for the direction of flow. They are frequently used for isolation purpose and when sealings in both the directions are required.

not frequently but always.

you may want to chekout lyons' valve designers handbook by Jerry Lyons.

RE: Types of valves and their usage?

zdas04

(Mechanical)

25 Jul 02 17:50

Ralph, I've never heard a Ball Valve manufacturer claim that ball valves had "an equal percentage flow characterisitcs and are therefore suited for control applications".  I've talked at length to all the major maufacturers and they all say that their ball valves are on/off devices with very poor throttling characteristics comparable to a gate valve.  The exotic variants (Vee-ball, zee-ball, etc) are pretty good throttle/control valves with pretty linear flow characteristics, but they are definately not ball valves.

It's interesting that your company prefers plug valves--any details on why a reduced port, high maintenance, non-bubble-tight valve would be preferable to a ball valve?  I've always thought of plug valves as the Fiat of valves, and some people love to drive Fiats.

David

RE: Types of valves and their usage?

ralphsare

(Structural)

27 Jul 02 00:36

what it means -for a given percentage change in valve opening will produce same percentage change in flow. the chart (% Cv max vc % ball opening) from ball valve mfr such as ktm and jamesbury will make it much clearer.

_____________
our plug valve spec is. A215 body rf 316ss plug, nonlubricated teflon sleeve & diapragm, fire safet to api 607, bolted bonnet, ptfe packing with carbin graphite filled ptfe ring, live loaded packing. that hardly qualify as a fiat. we have it but the number is not much. i would just like to make it a point that if one does not pay attention to the quality of valve purchased, just one valve (fiat or not) in critical service that fail will have an impact in the palnt run time and safety.

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News

When selecting a gate valve for your application, several factors should be considered to ensure optimal performance and reliability. Here are key factors to consider when choosing the right gate valve:

1. Valve Size and Pressure Rating: Determine the appropriate valve size based on the pipe diameter and flow requirements of your system. Consider the pressure rating needed to handle the maximum operating pressure in your application. Ensure the selected valve size and pressure rating match your system requirements to prevent flow restrictions or valve failure.

2. Valve Type: Gate valves come in different types, such as rising stem, non-rising stem, or slab gate valves. Consider the specific requirements of your application and select the appropriate valve type. Rising stem valves provide visual indication of the valve position, while non-rising stem valves are suitable for applications with limited space.

3. Material Selection: Choose the right valve material based on the compatibility with the media and the operating conditions. Consider the nature of the fluid (corrosive, abrasive, high temperature), and select a material that offers suitable corrosion resistance and mechanical strength. Common materials include cast iron, ductile iron, carbon steel, stainless steel, and various alloys.

4. Sealing Mechanism: Gate valves typically use either metal-to-metal or resilient (soft) seating mechanisms. Metal-to-metal seats provide excellent sealing but may be more susceptible to leakage in lower-pressure applications or when debris is present. Resilient seats, such as rubber or elastomer, offer better sealing in low-pressure or dirty service conditions. Consider the media characteristics, pressure, and temperature requirements to choose the appropriate sealing mechanism.

5. Operating Conditions: Evaluate the specific operating conditions of your system, including temperature, pressure, flow rate, and media properties. Ensure that the selected gate valve is designed to handle these conditions without compromising performance, integrity, or longevity. Consider any potential variations or fluctuations in operating conditions that may impact valve selection.

6. End Connections: Gate valves come with various end connection options, such as flanged, threaded, or welded ends. Select the appropriate end connections that match your piping system and installation requirements. Consider factors such as pipe material, system compatibility, and installation convenience.

7. Actuation and Automation: Determine if manual operation or automated actuation is required for your application. Manual handwheel operation is suitable for smaller valves or applications where frequent operation is not necessary. For larger or automated systems, consider pneumatic, electric, or hydraulic actuators for remote control and automated operation.

8. Standards and Certifications: Ensure that the selected gate valve complies with industry standards and certifications relevant to your application. Look for certifications such as API, ANSI, ISO, or specific regulatory requirements. Compliance with standards ensures that the valve meets quality, performance, and safety criteria.

9. Maintenance and Serviceability: Consider the ease of maintenance and serviceability of the gate valve. Look for features such as accessibility for maintenance, availability of spare parts, and ease of disassembly and reassembly. Valve designs that simplify maintenance tasks can help reduce downtime and extend the valve&#;s service life.

10. Budget Considerations: Evaluate the cost implications of different gate valve options, including the initial purchase cost, installation expenses, and long-term maintenance costs. Balancing performance requirements with budget constraints is essential to select a gate valve that provides the desired functionality and reliability within your allocated budget.

By carefully considering these factors, you can choose the right gate valve that meets the specific needs of your application, ensuring optimal performance, longevity, and reliability in your fluid handling system. Consulting with valve manufacturers, industry experts, or engineers can provide valuable guidance in the selection process.

If you are looking for more details, kindly visit Gate Valve Manufacturer.