Global Valve and Controls
23Apr/110

Top Notch Actuator And Valve Parts For Your Hvac Unit

The actuator and valve parts for your HVAC unit are very important to the functionality of your unit. The outside unit of your heat pump consists primarily of the condenser coil, a compressor and a fan. Most of the hard-working equipment is housed within the inside unit.

Any time your heat pump requires repair or maintenance, the technician will connect pressure gauges to make sure there is the correct amount of coolant. Liquid coolant will be added through a port on the outside unit if needed. Leaks are relatively rare, but they do occur. Occasionally coolant, also called refrigerant, will need to be drained and refilled.

Actuators and Parts

An actuator, by definition, is a mechanical device for moving or controlling a mechanism or system. Operated by some source of energy, it converts energy into motion. Consider the wheel and axle for example. Rotating the axle causes the wheel to move; and as a direct result, causing whatever is attached to the wheel to move as well.

Energy created by hydraulic fluid, electric current or pneumatic pressure may be converted into motion using an actuator. The actuator in your HVAC unit is likely controlled by electric current. They are used most commonly for inflow-control valves, pumps, motors, relays, switches and positioning drives.

The two most common types of actuator are hydraulic and electro-servo. A hydraulic actuator forces hydraulic fluid through cylinders or motors and is controlled by control valves. Hydraulic machinery produces very high amounts of power and makes use of a variety of actuators in the process.

A pneumatic actuator compresses air to use as its source of energy. They contain a piston, cylinder and valves. The piston is protected by the diaphragm, which keeps the compressed air in the upper portion of the cylinder. Air pressure pushes the diaphragm down, which moves the piston down as well.

Control Valves and Parts

Control valves are used to control the flow, pressure, temperature, or liquid level of various mechanisms. The valve may be partially opened or closed in order to maintain proper flow, pressure or temperature, as it does with your HVAC system. Control valves are generally opened or closed by using an electrical, hydraulic or pneumatic control system.

Valve bodies vary depending on their intended use. Angle valves consist of cage-style and disk-stack style bodies. Globe valves may have single, double or triple-way bodies as well as port guided single-port, balanced-plug cage-guided or high capacity cage-guided bodies. Rotary style bodies include butterfly, v-notch ball control, eccentric-disk control, eccentric-plug control valve bodies.

Control valve parts for your HVAC unit should always be purchased from a certified dealer or other trusted source. Replacing valves or parts isn't always an easy job and should be handled by a professional with experience.

Cost

Most replacement parts are relatively inexpensive. The most expensive part to replace is the compressor. It could cost several hundred dollars to replace a condenser. People often choose to replace the entire unit in lieu of simply replacing that single part.

The fan, control valves and actuators are fairly inexpensive to replace if they become worn out. They are in fact moving parts, so they do tend to wear out more quickly than parts that are stationary. Contact a professional HVAC technician if you feel that your heat pump or other HVAC unit isn't functioning to its potential.


About the Author:
HVAC Plus specializes in HVAC controls. Large selection includes Honeywell actuator and Honeywell valve parts for every need.

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29Mar/110

Oil’s Changing Landscape: Ship Low, Sell High

Oil’s Changing Landscape: Ship Low, Sell High

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At GVC we know our market, keeping up to date on all the latest news.
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Editor’s Note: This is the fourth in a multi-part series examining the fundamentals behind the structural transformation of the U.S. oil markets and the downstream logistics challenges that are resulting. The third installment covered the “disconnect” between inland crudes priced off Cushing crude values when the North American oil hub is flush with crude in storage. (Image Source: CN)
As geopolitical turmoil drives crude prices skyward and lifts retail gasoline to US$4.89 per gallon (/gal) in cities like Los Angeles, it’s anything but business as usual in the U.S. oil patch.
Inland producers who are left in the dust amid triple-digit waterborne crude prices on most every U.S. coast are pioneering inventive downstream logistics to ship crude at low cost to higher-priced markets – thereby avoiding the disconnect in the wild west of North America’s oil industry.
Nearly every multimodal logistics opportunity short of yesteryear’s Pony Express and today’s Federal Express is being considered to cost-effectively ship crude oil to profit from high-price spreads between landlocked and waterborne crudes.
In intra-day trading on March 2, a remarkable spread was logged as the West Canadian Select (WCS) grade saw discount pricing around $80.00 per barrel (/ bbl), while both Heavy Louisiana Sweet and Light Louisiana Sweet (HLS and LLS) crudes on the Gulf Coast traded at more than $122.00/bbl.
That astounding discount of more than $40.00/bbl represents 50% of the then current WCS value. The basis differential can partly be explained by crude quality, but these theoretically, wide-open arbitrage opportunities attract pioneering innovators like the land rush days of old.
Furthermore, the $19.70/bbl discount to LLS prices that day for 38 million barrels of crude stored inland at Cushing at the time represented $750 million in dollar terms.
In the void left by insufficient pipeline takeaway capacity, tankers are stepping in to ship crude via rail and inland waterways away from the heavily utilized and smaller Mid-Continent refining fleet toward a Gulf Coast refining fleet twice its size.
Canadian Railway Company Rides the Rails to the Rescue?
Canadian National Railway Co. (CN), based in Montreal, Quebec, has pioneered and trademarked, PipelineOnRail – described as an “economically sound, surprisingly fast way to ship crude oil products within Alberta to the rest of Canada, the U.S. Midwest, the Gulf coast and other export markets.”
The plan seeks to use its extensive North American rail system that already traverses the Canadian continent on an East-West axis to tank crude south along its interconnected rail spine spanning the U.S. down the Mississippi River valley all the way to and around the U.S. Gulf Coast.
On March 1, Hart Energy contacted CN’s Kelli Svendsen, senior manager of regional public and government affairs, and learned that “CN has been testing concepts to move crude (heavy, light, and pure bitumen) from areas in Western Canada to various markets in the U.S.”
Svendsen said two areas of Canada are already exporting crude oil to the U.S: “CN has moved pure bitumen from Fort McMurray to U.S. markets,” and “from the Bakken reserves in Saskatchewan (Canada) to the U.S.”
The Bakken effort began recently with shipments “in October 2010.” Svendsen said, adding that “CN is optimistic that rail will play an increasing role in the transport of crude moving forward.”
EnSys Study Documents Crude-by-Rail Potential
EnSys Energy noted in a December 2010 North American crude logistics assessment that “CN Rail currently imports condensate, for blending with oil-sands bitumen to make DilBit (a.k.a. diluted bitumen)” from the Kitimat Port on Canada’s west coast.
According to EnSys, the “PipelineOnRail … avoids the large, fixed investments associated with major pipelines.” EnSys also noted that CN indicates potential capacity to move “as many as 200,000 b/d or more.”
EnSys said the study did not allow for the expansion of the PipelineOnRail capacity in any scenario, because tariffs for rail are generally not considered attractive relative to pipelines.
“However, during a period of constrained pipeline capacity, the PipelineOnRail could compete as an alternative,” the assessment reads.
Pioneers on the U.S. Side of the Border
The Bakken petroleum that CN is shipping originates from a producing region that extends into the U.S. states of North Dakota and Montana. Drillers in North Dakota produce the area’s greatest share of petroleum using unconventional hydraulic fracturing and horizontal drilling techniques.
Justin Kringstad, director of the North Dakota Pipeline Authority (PA), wrote in a September 10, 2010, release: “Because of our distance to market, regional producers have always absorbed a per-barrel discount on production.” Yet he noted that recent increases in rail and pipeline “takeaway capacity has pared that discount down substantially.”
Kringstad tabulated new capacity for crude oil shipments from several takeaway projects, including new rail-loading terminals in the area. These include EOG Resource’s 65,000-b/d rail facility in Stanley, N.D., which began rail tanker shipments to Cushing, Okla., in December 2009.
Hart contacted EOG spokesperson K. Leonard on March 1, who shared that “EOG is currently utilizing five trains, with plans to add a sixth in the future.” Leonard said EOG leases the rail tankers it uses to ship crude.
“The company typically loads one train daily and regularly hauls 68,000 gross barrels of crude per train,” Leonard said, adding that “Each train has approximately 100 cars.”
North Dakota PA’s Kringstad further noted in his release that Hess Corp. is readying a $48-million, 60,000 b/d rail facility in Tioga, N.D., for an early-2012 start-up. His post also said that Dakota Transport Solutions began shipping crude from New Town, N.D., to St. James, La., in August 2010. Kringstad said that facility reportedly had the capacity to transport 20,000 b/d by the end of 2010.
Kringstad also noted that smaller rail facilities operate with an estimated combined capacity of 30,000 b/d and include North Dakota locations in Minot, Dore, Donnybrook and Stampede.
Rangeland Energy LLC a New Pioneer
Rangeland Energy LLC (Rangeland), based in Sugar Land, Texas, has also announced plans that would enable Bakken producers to ship crude by rail tanker to the U.S. Gulf Coast.
On March 1, Hart spoke with Chris Keene, Rangeland president and CEO, and learned the company is developing the “COLT” rail terminal hub or connector to ship 100 rail tankers daily (60,000 b/d) of Bakken crude via the BNSF Railway Company to points including the Gulf Coast.
Keene said his company was formed in 2009 and noted: “It’s a huge opportunity, and I think our facility that we are building will be extremely valuable to the industry. It’s been great.”
“There are new rail tank cars being built as we speak. As fast as they can build them, they are being leased. In fact, they are being leased before they build them. Tank car makers, Keene said, have a huge backlog at present – driven by this trend.
Although Keene would not name names, Hart learned that Dallas-based Trinity Industries, Inc., and Oregon-based The Greenbriar Companies, manufacture multi-modal tankers for rail, barge and/or land transport. A review of company disclosures suggested a confirmation of strong backlogs in tanker manufacturers.
The new rail tankers “are coming on because you have a huge demand that has grown not only in North Dakota but also in the Eagle Ford,” Keene added.
Shippers also “are doing whatever they can using existing fleets … a refiner that has an existing fleet of rail cars that maybe they were moving refined products. They convert them and move crude oil,” according to Keene.
“We have not looked at rail into Canada although we have talked with the folks working Saskatchewan’s Bakken trend. Everything we have looked at doing is in and around Williams County in North Dakota where we will be building,” Keene noted. “But certainly the opportunity exists wherever there is existing infrastructure, rail infrastructure, there is an opportunity to do manifest or unit trains.
“Currently, we have a huge draw to get it to the Gulf Coast, into the LLS market,” he said, but “non-traditional” markets for inland crude could soon take the rising flows shipped by rail tanker from Bakken and Eagle Ford producers. “Bakken crude is going to California at Bakersfield right now, by manifest trains, a few cars at a time.”
Keene further mused about the potential for Eagle Ford to flood the Gulf Coast, saying that this could back crude up at Cushing and further back in the Bakken.
“Now you have this rush of light, sweet crude coming on the market; where is it going to go? It’s an interesting story,” Keene said. “It will be interesting to see which refiners run it given that a lot of these refiners just a couple years ago were converting to run heavy, sour crude with investments of billions of dollars.”
Musket Trading Makes The Connection
On March 1, Hart Energy also contacted Oklahoma-based Musket Trading and spoke to Dan House, managing director of crude oil. House said the shifting North American oil industry landscape has “been pretty active as far as the changes that are going on. That creates opportunity, so it’s a good place for us.”
Musket owns and operates rail-served terminals; maintains some 2,000 railcars; provides shipment logistics in 39 states and Canada; and distributes crude oil and other commodities via more than 20,000 railcars annually. That includes crude from the Bakken region to the U.S. Gulf Coast.
House confirmed that rail shipments of Canadian crude are increasingly being talked about and occurring in small batches. “We have done a small amount of it, and I know there are a lot of people looking at it in a bigger way recently,” House said.
Regarding Eagle Ford production, House said producers there yield “a lot more condensate type material that will be railed out of the Eagle Ford. The crude seems to have a good local market, but the condensate volumes that they are talking about do not seem to have a natural home down there.”
Hart also asked House if the Eagle Ford condensate could be sent northward to Alberta’s bitumen producers for use as diluent instead of importing it at Kitimat and shipping it by CN rails to Alberta. House agreed that this opportunity is “most likely” and “that’s where we are seeing it make sense.”
Kirby Inland – Heavy Oil to Crude Tanker?
To obtain the waterborne tank barge perspective, Hart Energy spoke with Steve Holcomb, communications officer for Kirby Corp. in Houston – among the largest inland waterway shippers in the U.S.
According to Holcomb: “We carry very little crude oil. We’ve had a lot of inquiries into it, but they have got to get the product to the Mississippi River or the Arkansas River. So it’s a logistics problem of getting the crude to a river system that is navigable.”
When asked about CN’s rail plan, Holcomb said: “A tank barge would be much more economical way to move it than rail cars. But then, of course, you have to have access to [load the crude] on a viable waterway.”
“Our utilization is pretty high, so we don’t have a lot of barges available, but the industry may have some available … If you move refined products in a barge and you switch it over to crude service, then you have a significant cost of cleaning that barge. You cannot carry a petroleum product upriver and bring crude oil back.
“That doesn’t work. It must be dedicated,” Holcomb said, or the shipper could incur something like “$50,000 to $60,000 to clean it.” That cleaning cost could be justifiable, Holcomb said, if spread-over barrels shipped over a lengthy lease commitment.
“If it’s moved in a black oil barge, it’s a little different. We have 112 black oil barges out of our total fleet of 825,” Holcomb told Hart, noting that such costly cleaning procedures would be unnecessary.
Hart noted the EnSys stance that “rail linked in to barge (or tanker) could also play a role in the transport market. Small volumes of WCSB crudes are currently arriving in the Gulf Coast in part via barge.”
Holcomb offered assurance that “Somebody will figure it out before long. If it involves inland tank barges, Kirby will benefit, because it will tighten up the inland barge market. Barge availability will be much less than what it is today, and rates will begin to escalate.”
According to Holcomb, several other black oil barge firms provide similar services. If Hart Energy makes headway on researching those, they will be covered in a future segment of Hart Energy’s Oil’s Changing Landscape special series.

 

Oil’s Changing Landscape: Ship Low, Sell High
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5Mar/110

History & Mystery Of Ball Valve

The ball valve was invented in the early 1950s and consists of a spherical disc. With the rapid advancement in technology and improvement in the product structure and processing techniques, the quality valves has emerged as one of the main valves in recent times. Today it finds application in many industries all across the Globe.

Inside of those , there is a spherical ball having a hole in the middle. When it is aligned with both the valve ends, liquid can flow with ease through it. After the quality valve is fully closed, this hole becomes perpendicular to the valve ends thereby impeding any flow of liquid.

Due to their hassle free mechanism, valves are extensively used in different industries. They are also preferred due to their wide operating range for temperatures, pressures and versatility. The sizes of those range from 0.5 - 30 cm. They are manufactured using different materials like plastic, metal or metal having ceramic center.

For catering different industrial requirements, these valves are classified into various types. Considering them from the body perspective, they can be split body, single body, top entry, 3 piece body and welded. Though ball valves may be of different types, yet their operation is same.

Ball valve is also categorized according to the bore in its ball mechanism and comes in many styles. Usually they are cavity filler ball valves, reduced port, full port, V port and trunnion. Manually operated piston type are easy to close. Some valves used in the industries are also operated by a motor using an actuator.

Today the use of various kinds of piston type provides numerous benefits to different industries in the world. Without these valves, the process to control the fluid flow would certainly be a huge concern for all these processing and manufacturing companies.


About the Author:
Deborah is journalist and business specialists. She writes for several newspapers about business topics such as Ball Valve ,and several other which attract attention of many readers.

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1Mar/110

Forged Steel Valves

Forged Steel Valves

Products > Forged Steel Valves
products forged steel valves Forged Steel ValvesGVC offers forged steel valves in Class 800 and 1500 from ½” through 2”. 

Forged Steel Valves

Series FS-3

  • Forged Steel Gate Valve
  • ANSI Class 150 – 2500
  • Flanged, Threaded, and Socket Weld Ends
  • API 602 Design
  • Conventional or Full Port
  • Available in A105N, F316, F304, F11, F22, LF2, and other steel alloys

pdf icon Forged Steel ValvesDownload PDF

Series FS-4

  • Forged Steel Globe Valve
  • ANSI Class 150 – 2500
  • Flanged, Threaded, and Socket Weld Ends
  • API 602 Design
  • Conventional or Full Port
  • Available in A105N, F316, F304, F11, F22, LF2, and other steel alloys

pdf icon Forged Steel ValvesDownload PDF

Series FS-2

  • Forged Steel Check Valve
  • ANSI Class 150 – 2500
  • Flanged, Threaded, and Socket Weld Ends
  • Available in Piston, Ball, or Swing Design
  • API 602 Design
  • Conventional or Full Port
  • Available in A105N, F316, F304, F11, F22, LF2, and other steel alloys

pdf icon Forged Steel ValvesDownload PDF

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15Feb/110

2005 China (shanghai) International Valve Pipe Industry Exhibition – International, Valve,

Start time: 2005-05-30 End time: 2005-06-01 Venue: Shanghai World Trade Mart Contact: Otto Sponsor: On Haimaidawei Exhibition Service Co., Ltd.

Exhibition Group (Hong Kong) Co Ltd As China enters the WTO and the 2010 Shanghai World Expo bid is successful, to Shanghai's further opening up and development has brought new opportunities to promote local economic development, urbanization has become at this stage consensus. In order to build Shanghai into an investment environment and ecological environment the best international cities, to enhance urban functions, create an excellent living environment, to ensure sustained and healthy economic development, municipal, construction, environmental protection, electricity, gas, communications, transportation , water and many other areas of urban and rural infrastructure were included in the party once again the top priority of government work in the successful implementation and completion of municipal plans, but also to the pumps, valves Pipeline Products provide a broad market space, in 2003 industrial output valve 240 billion, pump and valve products have been the large-scale, high-speed, high parameters, high reliability, strong corrosion resistance, mechanical and electrical integration, program-controlled group control and Monitor Direction of Pipe and Tube Products of new technology, new equipment, new processes, new materials, rapid growth of demand.

Order to promote our country pumps, valves and piping industry healthy development of the domestic industry to expand exchanges and cooperation between, "2005 China (Shanghai) International Pump, Valve and Pipe Industry Exhibition", will be May 30, 2005? June 1 held in the Shanghai World Trade Shopping Mall. "Science and technology innovation, cooperation and development" as its theme, with quality service, scientific and comprehensive integration of communication, and a new market concept, for domestic pumps, valves and pipe supply and demand sides, to provide information dissemination, technical exchanges and economic and trade talks trading platform, to invite your organization exhibitors, visit.

An exhibition schedule Preparation time: May 28, 2005? 29
Exhibition time: May 30, 2005? June 1
II Exhibit Pump: pipeline pumps, chemical pumps, submersible pumps, gear pumps, magnetic drive pumps, corrosion-resistant pumps, impurities

Pump, heat pumps, hydraulic jet pumps, Centrifugal pump , Pump, pump, pump, piston pump,
Metering pump, steam pump, gear pump, screw pump, Roots pump, water pump, oil pump, injection pump,

Pump, Washing machine And various ancillary equipment
Valves: gate valve, globe valve, ball valve, check valve, plug valve, discharge valve, Filter Device, plunger

Valve, diaphragm valve, exhaust valve, piston valve, safety valve, reducing valve, throttle, solenoid valve, bottom
Valves, regulating valves, butterfly valves, steam traps, insulation valves, special valves, special valves, other valves
And valve actuator Pipeline: a variety of materials, pipes, fittings, steel pipe, buried heat preservation pipe, aluminum plastic composite pipe, PPR

Pipe, copper pipe, cast pipe, elbow, shaped pieces of corrugated expansion joint, flange, clamp connectors, screw

Pattern components, pipe components, dynamic seals and mechanical seals combine technology, pipe cutting equipment, welding
Access equipment, pipe and cable detection equipment, technology and water leakage detection equipment, corrosion-resistant rust-proof technology.

3, booth fees 1, standard booth 9? (3mx3m); configuration: three panels (2.5m high), fascia production, one table,

Two chairs, carpet, 220V/5A socket, two spotlights;
2, light to lease an area of not less than 36? (Light to no facilities); double opening stand of 20% surcharge fee.

Domestic enterprises to joint ventures of foreign companies
Booth 7800 12000 U.S. dollar $ 2800
Light to 800 /? Per 1000 /? Per $ 300 /? U.S.
IV, Proceedings Advertisement 1, to meet the exhibitors in the Exhibitor during the exhibition period to allow customers to understand and after that can communicate with in a timely manner contact the Organizing Committee Conference Proceedings will be published

carefully, journal version of 210mmx285mm, Cover 20,000 inside front cover 16,000 yuan 12,000 yuan 12,000 yuan title page

Inside back cover page of 10,000 yuan to 6,000 yuan in black and white color inside pages About 1,000 yuan to 3,000 yuan

2, free to publish in proceedings than 200 words Company
Five other advertising 1, tickets: Specifications 80mmx190mm, charges 4,800 yuan / 10 000, 30 000 from India.

2, inflatable arch: 15,000 Yuan / exhibition, placed in the main entrance hall.
3, Outdoor balloons: 5000 Yuan / exhibition, (including long 10mx banner width 90cm).
4, information kits: Color 6000 yuan / 1000.
Six, technology exchange Technical exchanges will be exhibitors at home and abroad professionals and clients to introduce their advanced technology and equipment, the best side

Type, and investigation of their products and technology into the feasibility of domestic and international markets the most effective way to exchange each

5,000 yuan will be 2 hours.
7, publicity and promotion Order to promote this exhibition is good, good service, to the interests of exhibitors as the center, to invite professional tour operators

Focus on the work of the Organizing Committee will implement comprehensive, multi-angle, deep-level publicity, invite more visitors to purchase

Business participants, Specific publicity campaign are as follows:
Magazine: "valve", "pump technology", " Chemical Equipment And Antisepsis Loss "," Petroleum Engineering Construction

Set "," Pipeline Technology and Equipment "," Pump Business "," China Water "," Petroleum Engineering Construction

Set "," HC Business Advertising "," Wenzhou, Yellow Pages, "" West Yellow Pages "," manual valve statements "

"China Construction Information", "petroleum and chemical equipment", "Valve World", "Water Science and Technology and Economy",

"Pipe industry today", "Steel", "underground pipeline management". Network Media: valve business network, pump and valve trading

Net, HC water industry business network, China Valve Network, to the drainage line, China Water Treatment Network, the proposed projects under construction in China

Network, China Gas Equipment Website, China Water Industry Network, China Business Network pipeline, China National Machinery Information Network, China's environmental protection

Net. Public Media: New People's Daily, Shanghai Morning Post, Shanghai TV, China Industry News, China Petrochemical News, stone

Oil pipeline and a number of media reports predecessor in the development of a large number of publicity before the show


About the Author:
The e-commerce company in China offers quality products such as China train wash machine , Sewage Treating Equipment , and more. For more , please visit car wash today!

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1Feb/110

Check Valve – China Customers Projects – Global Customers Projects Manufacturer

Types of check valves
A ball check valve in the open position to allow forward flow and closed position to block reverse flow
A ball check valve is a check valve in which the closing member, the movable part to block the flow, is a spherical ball. In some (but not all) ball check valves, the ball is spring-loaded to help keep it shut. For those designs without a spring, reverse flow is required to move the ball toward the seat and create a seal. The interior surface of the main seats of ball check valves are more or less conically-tapered to guide the ball into the seat and form a positive seal when stopping reverse flow.
Ball check valves are often very small, simple, and cheap. They are commonly used in liquid or gel minipump dispenser spigots, spray devices, some rubber bulbs for pumping air, etc., manual air pumps and some other pumps, and refillable dispensing syringes. Although the balls are most often made of metal, they can be made of other materials, or in some specialized cases out of artificial ruby. High pressure HPLC pumps and similar applications commonly use small inlet and outlet ball check valves with balls made of artificial ruby and seats made of artificial sapphire, both for hardness and chemical resistance. After prolonged use, such check valves can eventually wear out or the seat can develop a crack, requiring replacement. Therefore, such valves are made to be replaceable, sometimes placed in a small plastic body tightly-fitted inside a metal fitting which can withstand high pressure and which is screwed into the pump head.
There are similar check valves where the disc is not a ball, but some other shape, such as a poppet energized by a spring. Ball check valves should not be confused with ball valves, which is a different type of valve in which a ball acts as a controllable rotor to stop or direct flow.
A diaphragm check valve uses a flexing rubber diaphragm positioned to create a normally-closed valve. Pressure on the upstream side must be greater than the pressure on the downstream side by a certain amount, known as the pressure differential, for the check valve to open allowing flow. Once positive pressure stops, the diaphragm automatically flexes back to its original closed position.
A swing check valve or tilting disc check valve is check valve in which the disc, the movable part to block the flow, swings on a hinge or trunnion, either onto the seat to block reverse flow or off the seat to allow forward flow. The seat opening cross-section may be perpendicular to the centerline between the two ports or at an angle. Although swing check valves can come in various sizes, large check valves are often swing check valves. The flapper valve in a flush-toilet mechanism is an example of this type of valve. Tank pressure holding it closed is overcome by manual lift of the flapper. It then remains open until the tank drains and the flapper falls due to gravity. Another variation of this mechanism is the clapper valve, used in applications such firefighting and fire life safety systems. A hinged gate only remains open in the inflowing direction. The clapper valve often also has a spring that keeps the gate shut when there is no forward pressure.
A stop-check valve is a check valve with override control to stop flow regardless of flow direction or pressure. In addition to closing in response to backflow or insufficient forward pressure (normal check-valve behavior), it can also be deliberately shut by an external mechanism, thereby preventing any flow regardless of forward pressure.
A lift-check valve is a check valve in which the disc, sometimes called a lift, can be lifted up off its seat by higher pressure of inlet or upstream fluid to allow flow to the outlet or downstream side. A guide keeps motion of the disc on a vertical line, so the valve can later reseat properly. When the pressure is no longer higher, gravity or higher downstream pressure will cause the disc to lower onto its seat, shutting the valve to stop reverse flow.
A duckbill valve is a check valve in which flow proceeds through a soft tube that protrudes into the downstream side. Back-pressure collapses this tube, cutting off flow.
Multiple check valves can be connected in series. For example, a double check valve is often used as a backflow prevention device to keep potentially contaminated water from siphoning back into municipal water supply lines. There are also double ball check valves in which there are two ball/seat combinations sequentially in the same body to ensure positive leak-tight shutoff when blocking reverse flow; and piston check valves, wafer check valves, and ball-and-cone check valves.
Applications
Check valves are often used with some types of pumps. Piston-driven and diaphragm pumps such as metering pumps and pumps for chromatography commonly use inlet and outlet ball check valves. These valves often look like small cylinders attached to the pump head on the inlet and outlet lines. Many similar pump-like mechanisms for moving volumes of fluids around use check valves such as ball check valves.
Check valves are used in many fluid systems such as those in chemical and power plants, and in many other industrial processes.
Check valves are also often used when multiple gases are mixed into one gas stream. A check valve is installed on each of the individual gas streams to prevent mixing of the gases in the original source. For example, if a fuel and an oxidizer are to be mixed, then check valves will normally be used on both the fuel and oxidizer sources to ensure that the original gas cylinders remain pure and therefore nonflammable.
Some types of irrigation sprinklers and drip irrigation emitters have small check valves built into them to keep the lines from draining when the system is shut off.
Also used with most home made snowmakers.
Check valves used in domestic heating systems to prevent vertical convection, especially in combination with solar thermal installations, also are called gravity brake.
History
Frank P. Cotter developed a "simple self sealing check valve, adapted to be connected in the pipe connections without requiring special fittings and which may be readily opened for inspection or repair" 1907 (U.S. patent #865,631).
Nikola Tesla invented a deceptively simple one-way valve for fluids in 1916 (U.S. patent #1,329,559; patented 1920).
Images
Hastelloy check valves
Stainless steel wafer check valve
Inconel check valve
Inside view of a tilting disc inconel check valve
Flanged nozzle inconel check valve or axial check valve
This Siamese clappered inlet allows one or two inputs into a deluge gun.
Inside hastelloy check valve, wafer configuration
Large carbon steel swing check valve
Disc for an alloy check valve also known as axial check valve
Wafer check valve
Nuts and bolts for incoloy valves
Inconel check valve springs
References
^ Wright, Stephen. "Norval valve performance". Northvale Korting. http://www.northvalekorting.co.uk/prod-norval-perf.asp. Retrieved 2009-05-19. 
See also
Diode, the electrical analog of a check valve
Reed valve
Top feed
Vacuum breaker
External links
Check Valves Tutorial The operation, benefits, applications and selection of different designs, including lift, disc, swing and wafer check valves are explained in this tutorial
A picture of a microscopic checkvalve, a scaled down version of Tesla's original fluidic diode.
US Patent 1,329,559, Tesla's original fluidic diode (a test of a design showing very poor performance - n.b. the test protocol did not match the conditions described in the patent)
Categories: Plumbing valves | Firefighting equipment | ValvesHidden categories: Articles lacking sources from November 2008 | All articles lacking sources


About the Author:
The e-commerce company in China offers quality products such as CHINA Customers Projects , GLOBAL Customers Projects Manufacturer, and more. For more , please visit 3D Theater System today!

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