Fixed vs. Variable Displacement Vane Pumps

A hydraulic drive system uses a pressurized fluid to deliver force to distant machinery. Each system has several common components; the most universal is the hydraulic pump. The pump’s purpose is to pressurize the hydraulic fluid so that it will travel down the line and perform work on the other side. In an ‘open loop’ system, the fluid is drawn from a reserve tank, and deposited into the same tank after it has done its work. In a ‘closed loop’ system, the fluid is brought directly back to the hydraulic pump after passing through a hydraulic filter.

 

Fixed Displacement Pumps

A fixed-displacement pump has a set flow rate — every stroke of the motor moves the same amount of fluid. Fixed-displacement pumps are

 

  • Simple
  • Relatively inexpensive
  • Easier to maintain

 

The simplest type of fixed-displacement pump is the gear pump, in which the hydraulic fluid is pushed by rotating gears. In some models, the gears are sequential; in the quieter and more efficient version, the gears are interlocking. Another common variation is the screw pump, which uses the classic Archimedes screw, which looks much like a drill bit, to move the fluid. They have the advantage of providing a high rate of flow at relatively low pressures.

 

Variable Displacement Pumps

In a variable displacement vane pump, the flow rate and outlet pressure can be changed as the pump operates. This results in pumps that are

 

  • More complex
  • More expensive
  • Capable of doing a wider variety of jobs

 

The most common type of variable-displacement pump is the rotary vane pump, which is a variation of the gear pump in which the ‘gear’ is offset and the ‘cogs’ aren’t fixed, but rather extend and retract as the gear turns, allowing the pump to increase the pressure of the fluid by compacting it as it pushes the fluid through. The top-tier pumps, however, are bent-axis piston-and-cylinder pumps, much like the ones that are used in an internal combustion engine.

 

Simple, fixed-displacement pumps are perfect for single jobs that need to be repeated indefinitely over long periods of time; variable displacement vane pumps can be used to power a wider variety of tools, but require more expense and more attention.

 

As the outstanding hydraulic pump supplier, Anson always follows our policy “Technology upgrading, quality insistence, comprehensive service “. Anson committed to provide high quality vane pumps for customers, including intra vane fixed displacement vane pump, variable displacement vane pump, and power mini-pack unit and so on products.

 

If you need more information about variable vane pump and hydraulic pumps, welcome to visit Anson’s website to obtain further details.

 

 

Article Source: http://peerlessengineering.com/blog/hydraulic-pumps-fixed-vs-variable-displacement/

Share

Bad Valve Seals and Piston Rings Symptoms & Replacement Cost

This discussion is about the symptoms of bad valve seals and piston rings as well as their basic functions and common cost of replacement. Valve seals and piston rings are crucial for the functionality of your engine. If you can recognize the signs of when these components have problems, then you can replace them right away before serious damage is done to your engine.

 

Functions of Piston Rings

 

The piston is located inside of a car’s engine. The piston ring comes in the form of a split type ring and you install it outside of the piston’s diameter. The piston ring’s main purpose is to assist in sealing the combustion chamber, manage the oil consumption of the engine, and to assist in transferring heat to the engine from the piston. It is important to note that the piston ring will eventually get worn out, which means you’ll have to replace it. You should go to a professional mechanic to have this replacement job done.

 

Functions of Valve Seals

 

After air and fuel are mixed together, valves are there to manage how much of the mixture flows through the cylinders before the combustion process takes place. Valves usually have sleeves on them which prevent the combustion gasses from seeping out of them. The tops of the valves also have seals on them which prevent oil from getting pulled down into the engine area. These seals are commonly constructed out of a super strength rubber material and they’re placed into a small collar of the valve stem’s top area. Once these valve seals start to get worn out, you’ll notice some major symptoms that are unique to this problem.

 

The Symptoms of Bad Valve Seals and Piston Rings

 

The symptoms of bad valve seals and bad piston rings are quite similar. Any time either one of them fails, the performance of the vehicle will be reduced along with other bad symptoms that are noticeable. Let’s take a look at some warning signs which might indicate that you have bad valve seals or piston rings.

 

  • Exhaust Smoke – If you notice thick smoke that’s a gray or white color, this indicates that your car is burning oil. The only way this could happen is if the oil is leaking into the combustion chamber of your engine.

 

  • Too Much Oil Being Consumed – If the piston rings are worn out and the valve seal is broken, this will be what allows oil to flow into the combustion chamber.

 

  • Not Enough Accelerating Power – When there is damage to the piston rings and valve seals, the compression will be reduced which causes you to lose power in your engine. As a result, you won’t be able to accelerate when you put your foot on the gas pedal.

 

Although bad valve seals and piston rings have similar symptoms, the time and costs of repairing them are quite different. That is why you should educate yourself about where the problem is coming from, whether it’s the valve seals or piston rings. Once you find out, you can save time and money from having a mechanic figure it out for you.

 

To investigate where the problem is coming from, there are a few tips you can follow which will help you out with this. You can open the spark plug, fill up the cylinder with some oil, do a compression test, remove the EFI fuse and crank the engine, and then see the result of the compression gauge. If the result of the compression test appears to be good or at least average, then the piston rings are likely the problem. However, if the results of the compression test are low or under average, then the valve seals are the problem.

 

Replacement Cost of Piston Rings

 

When replacing piston rings, the cost will be determined by several factors. The make and model of your vehicle is one example. You also have to consider the type of engine that’s in your car and the condition of it. Most mechanics are going to charge around $1,500 minimum to perform this job. Some may even charge as much as $2,500. The reason this replacement job is so expensive is because it is a complicated task. The engine of the vehicle has to be completely disassembled first and then the cylinders of the vehicle have to be reconditioned. After that, the car gets reassembled using all the parts that were taken off originally. Only an experienced mechanic can perform this task, which is a very long and intense project that takes several hours to do.

 

Replacement Cost of Valve Seals

If you have discovered there is damage to your valve seals, then have an auto technician install new oil seals. The cost of this replacement job will be between $900 and $1,800, depending on the make and model of your vehicle. The process of replacing the valve seals requires disassembling the entire engine until you can reach the valve spring. Take off the cylinder head cover, the spark plugs, pushrods, and rocker arms. The amount of time this will take depends on the make and model of your vehicle. Sometimes the technician may have trouble with this job, so they’ll dismantle and remove the cylinder head. Then they’ll use a cylinder kit as a replacement which contains a cylinder head gasket.

 

Conclusion

 

There are lots of reasons why damage can occur to valve seals and piston rings. But if you regularly maintain your vehicle and get it serviced, then the damage to these components will be minimal. Vehicles that are maintained poorly or have high mileage are prime candidates for having damaged valve seals and piston rings.

 

If you are interested in learning more information about valve seals, try to visit the website of AOK Valve Stem Seals Ltd. AOK is a Taiwan local company of specializing in producing bonded seals, O-rings, and valve stem oil seals. Feel free to contact AOK you will obtain the details you need.

 

 

Article Source: http://cartreatments.com/valve-seals-and-piston-rings-symptoms-replacement-cost/

Share

Hydraulic Modular Valves and Manifolds

Valves are normally mounted onto a valve skid with piping at the rear, or underneath, to allow quick changes to be made for maintenance purposes. Piping can, however, be dispensed with almost totally by mounting valves onto a manifold block- with interconnections formed by drilled passages in a solid block or by cut-outs on a plate-formed manifold.

 

Modular valve assemblies allow piping to be reduced still further. These follow standards laid down by the Comit~ European des Transmission Oleophydrauliques et Pneumatiques and are consequently known as CETOP modular valves.

 

Modular valves consist of a base plate, shown in Figure 4.45a, and a wide variety of modules which may be stacked up on top. Figures 4.45b to d show some modules available. At the top of the stack a spool valve or crossover plate is fitted. Quite complicated assemblies can be built up with minimal piping and the ease of a child’s building block model.

CETOP Modular Valves

 

Mentioned modular valve, I can recommend you to visit the website of ASHUN if you are interested in learning more information about valves. Ashun was established in 1984 as a manufacturer for hydraulic and pneumatic products. For the hydraulic valves, they have 01 series modular valves, directional control valves, pressure control valves and flow control valves. Especially 01 series modular valves which can be afforded high pressure (31.5MPa) and large flow (40L/min).

 

Need further details about modular valves, please feel free to contact with ASHUN.

 

 

Article Source: http://www.valvehydraulic.info/valve-2/hydraulic-modular-valves-and-manifolds.html

Share

Why Do Engineers Use Stainless Steel Ball Valves?

As time goes on engineers continue to develop new technology improving operation services for a variety of businesses in a wide array of sectors. The form of the stainless steel ball valve is no different. It has altered in shape and has been modified to achieve maximum results over the years. It is a reflection of the technological advances that have been made by engineers today.

 

A steel ball valve is located inside a tube and enables waste fluids to travel through a passageway. The valve works by placing an existing hole in the steel ball then the placement of the ball is what controls the function of this valve. Once the holes are proceeding in the same direction as that of the passageways the valve stays open. The fluid begins to stream out in an uninterrupted manner. This is vital to the function of the contraption because if the holes are not lined up correctly then the valve closes and the fluid remains encased.

 

Why Stainless Steel?

 

To effectively execute its function, the valve needs to be strong and untainted when exposed to extreme temperatures and pressures. Sometimes the metal valves connect joints that carry a maximum of 200 degrees. Thus, it needs to handle working under such circumstances without dissolving or bowing. Engineers found this metal to fulfill all of these requirements and then some.

 

It also comes in different sizes and shapes. This is for you to find the exact valve size you need for your operations.

 

Also, these are able to come in two designs, sanitary or industrial. The sanitary ones are designed for the pharmaceutical, cosmetic, food, dairy and beverage industries. When you are looking to purchase one of these specify what industry you need the device for. This way you are guided towards equipment suitable to match your business needs.

 

In daily life, some recognizable valves are used in tap water, plumbing, dishwashers and hot water systems. It is easy to comprehend its mechanical function and purpose if you think about how veins and the heart work inside our own bodies.

 

Veins act as a valve permitting the flow of blood to the heart while maintaining a steady, correct pace. If you choose the right stainless steel ball valves for your business then it should act in the same manner.

 

Think about what type of business you are using the equipment for and narrow in on the products recommended, required by law and what material outlasts the rest.

 

Golden Highope Industrial Inc. Ltd. has specialized in manufacturing stainless steel ball valves since 1990, with years of experiences we provide only high quality ball valves to clients. Here we offer more various specification stainless steel valves for you to choose. Check the full Stainless & Carbon Steel Valve series on the website of Golden Highope and feel free to contact with us for further details!

 

 

Article Source: http://EzineArticles.com/7050531

Share

What is a Pressure Control Valve and Why Do You Need It?

Pressure control valves are found in virtually every hydraulic system, and they assist in a variety of functions, from keeping system pressures safely below a desired upper limit to maintaining a set pressure in part of a circuit.

 

Every pressure control valve switches (or controls) at a predetermined pressure setting. The switching pressure is generally a variable setting on the valve itself. A change in position of the pressure control valve (i.e. open or closed) occurs either gradually (by control) or suddenly (by switch). Pressure shut-off valves and pressure sequence valves are hydraulic valves with a fixed throttle whereas relief and reducing valves are hydraulic valves with a variable throttle.

 

Pressure valves are hydraulic valves that gradually (control) or suddenly (switch) change in position.

 

The most common types of pressure control valves are the pressure relief valve and the pressure reducing valve. Pressure relief valves control the system pressure by relieving part, or all, of the flow to tank. Pressure reducing valves reduce the pressure supplied to a sub-system of a hydraulic system. Sequence valves are used to direct the flow to a secondary circuit. Unloading valves are used to direct flow to tank at pre-set system pressure.

 

Type of Pressure Control Valves

 

  • Pressure valves, relief function
  • Pressure valves, reducing function
  • Pressure valves, fixed throttle

 

A hydraulic system can only function – as per requirements – by using valves. Thus, you should always look for the correct type of hydraulic valve to serve your intended purpose. You can try to browse the website of ASHUN, the professional hydraulic valves manufacturer in the industry, to get more information about pressure control valves. If you have any questions, welcome to contact with ASHUN via email or telephone!

 

 

Article Source: https://dta.eu/hydraulics/hydraulic-valves/pressure-controls/

Article Source: http://www.hydraulicspneumatics.com/200/TechZone/HydraulicValves/Article/False/6411/TechZone-HydraulicValves

Share

Optimum Flow Control Contributes Towards Reducing Manufacturing Costs

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

Share

What Is a Flanged Ball Valve?

Based on the ball-socket design, the ball valve is an in-line device shaped like a ball with an orifice through its center. When oriented correctly, the ball valve allows product to flow through easily. By grabbing the handle and turning the ball perpendicular or sideways, an individual can stop the flow. Found in almost every industrial environment, a flanged ball valve helps to control the flow rate through any plumbing application. The flanged ball valve is similar to the standard ball valve, but has mating connections or flanges that allow for quick and easy replacement of a damaged valve.

 

For instance, a valve without flanges would require an individual to manually cut piping and then reconnect it with a new valve in place. This reconnection can introduce additional hazards, as well as increased costs. In other words, some plumbing connections might require welding, soldering, or machining threads onto the ends of pipes for threaded applications.

 

When replacing a flanged ball valve, an individual should look for the bolted connections on either side of the valve. Loosening and removing the bolts from the flanges will allow the new ball valve to replace the broken ball valve. The modular design of flanged ball valves lends to their popularity, since a new flanged ball valve can bolt right into place of an old one. This ease of replacement is why flanged ball valves are commonly used when rapid repairs are essential.

 

A variety of flanged ball valves are available to cover nearly any application. Regulations exist to govern the varying sizes one may encounter. In the United States, for example, the American Society of Mechanical Engineers (ASME) governs the regulations, or codes. These regulations ensure that one flanged ball valve bears the same specifications as another, even if created by different manufacturers. The fact that one ASME flanged ball valve can replace another of the same size increases the interchangeability.

 

Valves come in many different configurations, such as the knobs on the kitchen sink, which are typically ball valves. These are generally found at some midpoint in a typical plumbing configuration. The best application for a ball valve is to quickly and easily stop product from flowing through pipes or plumbing, allowing for repairs to take place. A flanged ball valve has a variety of plumbing applications, mostly industrial, yet features the simple operation of the un-flanged variety, which requires merely moving a handle one quarter of a turn. In this model, flanges on either side of the actual valve make replacements of a broken valve relatively easy.

 

Wellgrow Industries Corp. is the professional ball valve and gate valve manufacturer in the industry. We offer a variety of valves likes flanged ball valve, globe valve, butterfly valve, diverter valve and so on products. If you are interested in learning further specification and details about flanged ball valve series, welcome to browse Wellgrow’s website or contact with us directly!

 

Article Source: http://www.wisegeek.com/what-is-a-flanged-ball-valve.htm

Share

Important Components in Fluid Power Industry – Hydraulic Valves

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

Share

What is a Globe Valve and Where are They Used?

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

 

Share

How do Pilot Operated and Direct Operated Solenoid Valves Work?

What are Solenoid Valves?

A solenoid valve is an electro-mechanical valve that is used to control the flow of liquid or gas. The solenoid starts by converting an electrical signal into a mechanical movement. The signal is then sent to a coil and the movement then occurs inside of the valve. Solenoid valves are usually be described as pilot operated or direct operated/acting.

 

Pilot Operated Solenoid Valves

2 way pilot operated solenoid valves have two chambers separated by a diaphragm. The upper chamber is connected to upstream through a pilot hole in either the cover or diaphragm. The media exerts a pressure that acts on the upper side of the diaphragm and keeps the valve closed. When the coil is charged the core lifts off the orifice seat allowing the operating chamber to de-pressurize. The thrust of the upstream pressure under the diaphragm continues, lifting the diaphragm and opening the valve.

 

Pilot operated solenoid valves only operate with a suitable upstream pressure differential and do not operate at zero pressure. Also a minimum pressure differential across the valve is required to keep them open or closed. Pilot operated solenoid valves can provide high flow rates at high pressures with lower power consumption.

 

Direct Acting Solenoid Valves

Direct acting solenoid valves do not use a diaphragm, their seal is part of the moving core. Two way NC direct acting solenoid valves have a spring that holds the core against the seal. When the coil is charged the spring is overcome and the seal is lifted from the orifice seat thus opening the valve and allowing the media to pass through the valve.

 

Two way NO direct acting solenoid valves have a fixed core which usually in the bottom section of the armature tube. The armature is located in the upper part of the valve. A stem passes through the fixed core and is coupled to the seal. This is held off the seal by means of a spring and makes a seal when the coil is energized, thus closing the valve.

 

Three way direct acting solenoid valves work in almost the same way as a two way direct acting solenoid valve. The fixed core has an exhaust orifice running through it. The plunger has an upper seal and lower seal allowing flow to or from either the body seat or exhaust.

 

Direct acting solenoid valves are used when there is no line pressure applied. Typical applications would include a cleaning line when a pump supplies bursts of water through the line. A direct operated solenoid valve would remain closed, even when no pressure is being applied (i.e. in between the busts of water). This is in contrast to a pilot operated valve, which requires some pressure for the valve to stay closed.

 

Excellent Solenoid Valve Manufacturer in Taiwan

SHAKO is one of leading and the largest professional pneumatic solenoid valve manufacturers in Taiwan. With rich experiences and in-deep knowledge, we are able to provide pneumatic solenoid valve products with excellent high quality & rapid service for various industries. If you need more information about solenoid valve series, welcome to visit the website of SHAKO.

 

 

Article Source: http://www.bmengineering.co.uk/news/solenoid-valves/How-do-pilot-operated-and-direct-operated-solenoid-valves-work

 

Share