Tag Archives: valves

Introduction of Globe Valves

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Cast Steel Globe Valve

A globe valves is a linear motion valve and are primarily designed to stop, start and regulate flow. The disk of a Globe valve can be totally removed from the flowpath or it can completely close the flowpath.

 

Conventional Globe valves may be used for isolation and throttling services. Although these valves exhibit slightly higher pressure drops than straight=through valves (e.g., gate, plug, ball, etc.), they may be used where the pressure drop through the valve is not a controlling factor.

 

Because the entire system pressure exerted on the disc is transferred to the valve stem, the practical size limit for these valves is NPS 12 (DN 300). Globe valves larger than NPS 12 (DN 300) are an exception rather than the rule. Larger valves would require that enormous forces be exerted on the stem to open or close the valve under pressure. Globe valves in sizes up to NPS 48 (DN 1200) have been manufactured and used.

 

Globe valves are extensively employed to control flow. The range of flow control, pressure drop, and duty must be considered in the design of the valve to avert premature failure and to assure satisfactory service. Valves subjected to high-differential pressure-throttling service require specially designed valve trim.

 

Generally the maximum differential pressure across the valve disc should not exceed 20 percent of the maximum upstream pressure or 200 psi (1380 kPa), whichever is less. Valves with special trim may be designed for applications exceeding these differential pressure limits.

 

Advantages

  • Can be fast-acting
  • Precise control
  • Can be used in high-pressure systems

 

Disadvantages

  • High head loss
  • Large opening for disk assembly
  • Heavier than other valves
  • Cantilevered mounting of the disk to the stem
  • Low coefficient of flow
  • Not good for clean or sterile applications

 

The most common application of the globe valve is a standard water faucet. When the handle is turned, a disc is lowered or raised. When the disc is fully lowered, the water supply is shut off.

 

Typical Applications Of Globe Valves Include:

  • Cooling water systems where flow needs to be regulated
  • Fuel oil systems where flow is regulated and watertightness is of importance
  • High-point vents and low-point drains when watertightness and safety are major considerations
  • Feedwater, chemical feed, condenser air extraction and extraction drain systems
  • Boiler vents and drains, main steam vents and drains, and heater drains
  • Turbine seals and drains
  • Turbine lube oil system

 

If you need more choice of globe valves, I recommend that you can visit Nico Valves Corp. – the company specializes in kinds of high quality valves including cast steel globe valve, gate valve, check valve, threaded valve, and much more. Now, welcome to check out Nico’s website and feel free to contact them.

 

Article Source: https://2bnews.wordpress.com/2018/07/10/introduction-of-globe-valves-2/

Optimum Flow Control Contributes Towards Reducing Manufacturing Costs

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Oil and gas companies around the globe face the challenge of increasing production and delivering quality products while reducing resources and manufacturing costs. Process control has a financial impact and so reducing process variability is, therefore, a key factor in maximizing quality output and reducing costs. Comprehensive studies of control systems have shown that up to 80% of control loops have not performed satisfactorily in reducing process variability. In most instances, the control valve was found to be the major cause of the problem. Despite this, the impact of the flow control valve on dynamic performance is often overlooked.

 

Optimum flow control is imperative; choke and control valves are subject to a variety of technical phenomena and careful selection of the right control valve for each application is crucial.

 

Superior design features include the valve material, which should be resistant to the chemical composition of the flow medium. For example, discs and internals made of solid Tungsten Carbide, renowned for its erosion and cavitation resistant properties. Industrial diamond facings inserted on the discs have also produced some very good results under severe conditions. The sealing surface must not be in contact with the flowing medium to ensure seat tightness can be guaranteed for a longer period of time. The construction of the internals should ensure that the downstream of the back disc is abrasive resistant. This removes the majority of cavitation and erosive material from the sealing surfaces as well as from the valve body. The design of the internals must be able to absorb turbulence in the flow so that the outgoing flow is more laminar. Rotating choke disc valves are recommended for extremely severe applications.

 

Flow control valves are also optimized by using different shaped and sized throttling orifices in the rotating discs. This affects the Cv value of the valve and has a crucial impact on process control. The right valve size and trim must be chosen to match the process conditions.

 

For both new and existing applications, to ensure downtime is kept to an absolute minimum and additional costs are not incurred, flow control valves should ideally be engineered to fit with no modifications to existing pipework. This also ensures that any replacements can be made efficiently.

 

Ultimately, these design features coupled with repairable internals and easy maintenance maximize production output, lower life-cycle costs and extend the mean time between failures, providing an overall reduction in total cost of ownership.

 

Found in 1984, ASHUN has established a fine reputation worldwide. Our professional R & D team develops new products continuously to meet our customers’ needs. If you need more information about flow control valves or other valves, welcome to browse our website or contact with ASHUN directly!

 

 

Article Source: http://EzineArticles.com/7478601

Important Components in Fluid Power Industry – Hydraulic Valves

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Hydraulic valves are essential as they help control the flow of any liquid specifically, oil, in the system. Choosing the most suitable valve(s) is crucial to any hydraulic system. It comes in different sizes and types depending on the pressure of the system as well as the flow rate.

 

3 Main Classifications of Hydraulic Valves

 

There are 3 main classifications of hydraulic – directional, pressure and flow control. Directional are used to control the fluid’s direction from the start to the end. Pressure valves however are used when a specific pressure level is required. The flow controls are used to control the flow rate of the fluid in the system.

 

Other Types

 

Aside from the main classifications, there are special hydraulic valves that are used dependent on the requirement. Some examples would be multi-block directional, modular, cartridge, electro-hydraulic servo, electro-hydraulic proportional/digital, micro-hydraulic and water pressure control.

 

Multi-block directional ones are composed of a main valve with several valves including a directional, a pressure and a check valve that is used to centralize control of the machine. The safest and most environmental friendly valve on the other hand is the water pressure valve which is used to control water in many water hydraulic systems.

 

4 Ways of Valve Installation Connection

 

Hydraulic valves are essential to a complete system. That being said, there are four different ways that valves are installed and connected – threaded, modular, sandwich plate and cartridge.

 

  1. Threaded:

These valves are usually used for small flow systems as they are lightweight. This valve is very popular and can be mounted along pipelines.

 

  1. Modular:

Modular valves are often used with modeling and pressing machines as well as with hydraulic power units. The valve makes use of valve sub-plate to connect with pipelines.

 

  1. Sandwich:

These valves are flexible as one can use it as a single unit or as part of the hydraulic oil connection. Often, the valve is sandwiched between a direction control and a sub-plate to connect with the pipe system.

 

  1. Cartridge:

Cartridges are divided into two different styles – cover plate or a two-way cartridge valve/threaded which can be two or more cartridges. The valves are made with sleeves, seat, spring, spools and sealing rings. Once all the parts are assembled, the valve is then inserted into a valve cavity. The cavity helps protect the parts inside making it suitable for heavy machine use.

 

These are just a brief overview of the different types of valves and hopefully provide readers an idea helping them make smart decisions later on.

 

Ashun was established in 1984 as a manufacturer for hydraulic and pneumatic products; we design and develop high quality and competitive hydraulic valves and pneumatic valves. We also offer customization service. Welcome to contact with Ashun to learn more information about cylinders and valves.

 

 

Article Source: http://EzineArticles.com/8967413

What is a Globe Valve and Where are They Used?

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Globe valves are linear motion valves that are widely employed to stop, start and throttle flow. In this article, we will have a simple introduction about globe valve function, advantages and disadvantages, and common applications of globe valves.

 

Globe valves are designed with a stem that moves up and down to regulate flow inside the valve, a disc (ball, composition, or plug) and seat, which is generally screwed into the valve body. Seats are designed in plane parallel or inclined to the line of the flow. These types of modulating valves are most commonly used to valve throttle, open or close flow in a system. The three basic globe valve body designs are Wye, Tee and Angle.

 

Advantages and Disadvantages of Globe Valves

 

Advantages:

 

  • Good shutoff capability.
  • Moderate to good valve throttling capability.
  • Shorter stroke (compared to a gate valve).
  • Easy to machine or resurface the seats.
  • Can be used as a stop-check valve.

 

Disadvantages:

 

  • Higher pressure drop (compared to a gate valve).
  • Requires greater force or a larger actuator to seat the valve.

 

Typical Globe Valve Applications

 

The following are some of the typical applications of globe valves:

 

  • Cooling water systems.
  • Fuel oil systems.
  • Feedwater or chemical feed systems.
  • Boiler and main steam vents and drains.
  • Turbine lube oil system and others.

 

NICO Valves Corp. is a leading industrial valve manufacturer in Taiwan and China and has been exporting this line of products for more than 20 years to all over the world.

 

We have full qualification for manufacturing widest kind of industrial valves in all common sizes & customized sizes, and available in ANSI, JIS, DIN standards. Its products includes: Gate, Globe, Check, Ball Valve, Knife Gate Valve, and Y-strainer. If you need more information about globe valves and other industrial valve series, welcome to browse NICO’s website or contact with us directly for further details!

 

 

Article Source: http://www.bmengineering.co.uk/news/globe-valves/what-is-a-globe-valve-and-where-are-they-used