Technical Details

Starting and Stopping Flow: Gate, Ball and Butterfly Valves are the most common form of shut-off valve, with ball and even butterfly valves rapidly becoming the primary choice due to the ease of automation and fast shut-off abilities, and in the case of ball valves the barest minimum of flow restrictions. We are often supplying ball and butterfly valves fully actuated, as plants of today become more and more automated, and are often now run by computers and the flick of a switch.

Regulating Flow: Regulating or throttling flow is most commonly done with the use of a globe valve, and to a much lesser extent an angle valve. The seat design forces the flow evenly around a disc or plug arrangement that enables a closer regulation of flow. Globe valves are often used for the control of steam. Your garden tap is a very common and basic form of a globe valve design.

Preventing Back Flow: This is the function of a check valve; it prevents flow reversal in piping, a primary cause of water hammer. Check valves most commonly are swing checks, normally used with gates and ball valves, and lift check or spring checks, which are normally used with Globe and Control type valves. In addition we exclusively offer you three new concepts of NRVs…Ball type and Hydrodynamic Guided closing type. Which have an innovative design to securely prevent the back flow of any medium, any pressure, also its unique design makes it possible to mount it anyway Horizontal, Vertical or Angular. The third one is Non-Slam check valve/stainless steel disc check valve(DCV) is of the wafer pattern designed to be sandwiched between flanges. It is suitable for use on a wide range of fluids for applications in process lines, hot water systems, steam and condensatesystems etc.

Regulating Pressure: Pressure Regulators and Control Valves are used to reduce incoming pressure and maintain it at a required service pressure. Fluctuations to the inlet pressures of a pressure regulator will not affect the outlet pressure for which it is set at.

Relieving Pressure: These are known as Safety Valves, normally used for steam, air, and gases, and Relief Valves, usually used for liquids. These are normally spring loaded valves which open automatically when the pressure exceeds a set limit. They can either vent to atmosphere or to other piping. Excessive pressures in something like a Boiler could cause major damage, if a relief valve was not used.

When in doubt you should always check with an expert, and Flow-Tech Enterprise will always assist you in the valve selection process, with our wealth of experience.

But first of all you should know the service conditions.

- Where the valve is to be used i.e. what function you want to perform?
- What are the pressure/temperature requirements?
- What kind of fluids will be in the line?
- What size is the line?
- How much room have you got for valve stems/handles?
- What are the service requirements, are the valves to be regularly dismantled for cleaning?

If you can answer these questions the choice of valve becomes evident very quickly, especially to one of our experienced valve sales staff. 

Brass and Bronze: Brass is the stock standard material used in most small bore, standard cold water applications. Bronze an alloy of copper, tin, lead and zinc, is normally used for steam and higher temperatures up to 230°C.

Cast Iron (CI): It is is an alloy of iron, carbon and silicon. Normally used for lower pressure applications and in butterfly valves bodies where it provides a cost effective alternative to steel. It also has corrosion resistance that is improved over steel in certain environments. Common in the fire protection and water industry.

Ductile Iron (DI): Ductile Iron has a chemical composition similar to cast iron, but special treatment during the casting process enhances its metallurgical structure to yield higher mechanical properties and improved ductility similar to steel.

Carbon Steel (CS): Carbon Steel is recommended for higher pressure and temperature applications and/or in services conditions that may be too harsh for Brass, Bronze and Cast iron. It has very good mechanical properties, good resistance to stress corrosion and sulfides. Carbon Steel is very tough, and has excellent fatigue strength.

Stainless Steel 304 (SS304): SS304 is basic 18% chromium, 8% nickel austenitic stainless steel commonly used for valve body, stem and ball. It offers excellent resistance to a wide range of corrosives and atmospheric exposures.

Stainless Steel 316 (SS316): SS316 is chemically similar to SS304 except with the addition of molybdenum providing better corrosion and pitting resistance and higher strength at elevated temperatures. It is non-magnetic. SS316 has excellent corrosion resistance in a wide range of environments, is not susceptible to stress corrosion cracking, and is not affected by heat treatment.

Monel: A nickel-copper alloy used primarily as interior trim on valves. It is one of the most specified materials for corrosion resistance to sea and salt water. Monel is also very resistant to strong caustic solutions.

Inconel: A nickel-copper-molybdenum alloy with excellent corrosion resistance in a wide range of corrosive media and is especially resistant to pitting and crevice corrosion. Like Monel, it is a favorable choice for seawater applications but with far greater strength.

Polyvinyl Chloride (PVC): PVC is the most frequently used of all thermoplastic materials. It has been used successfully for over 40 years in such areas as chemical processing, chilled water distribution, deionized water lines, chemical drainage, and irrigation systems. PVC is characterized by high physical properties and resistance to corrosion and chemical attack by acids, alkalies, salt solutions, and many other chemicals. It is attacked, however, by polar solvents such as ketones, some chlorinated hydrocarbons and aromatics. The maximum service temperature of PVC is 60° C. PVC is joined by solvent cementing, threading, or flanging.

Polypropylene (PP): PP is lightweight and generally high in chemical resistance. Although polypropylene is slightly lower in physical properties compared to PVC, it is chemically resistant to organic solvents as well as acids and alkalies. Generally, polypropylene should not be used in contact with strong oxidizing acids, chlorinated hydrocarbons, and aromatics. Polypropylene has proved to be an excellent material for laboratory and industrial drainage where mixtures of acids, bases, and solvents are involved. Polypropylene is joined by the heat fusion process, threading or flanging.

Chlorinated Polyvinyl Chloride (CPVC): CPVC has physical properties at 20° C similar to those of PVC, and its chemical resistance is similar to or generally better than that of PVC. CPVC, with a design stress of 2000 psi and maximum service temperature of 100° C, has proven to be an excellent material for hot corrosive liquids, hot or cold water distribution, and similar applications above the temperature range of PVC. CPVC is joined by solvent cementing, threading or flanging.

Polyvinylidene Fluoride (PVDF): PVDF is a strong, tough and abrasion resistant fluorocarbon material. It resists distortion and retains most of its strength up to 140° C. It is chemically resistant to most acids, bases, and organic solvents and is ideally suited for handling wet or dry chlorine, bromine and other halogens. No other solid thermoplastic piping components can approach the combination of strength, chemical resistance and working temperatures of PVDF. PVDF is joined by the heat fusion process, threading or flanging.

Air Valves: Air valves allow metered fluid flow in one or both directions. They are used in pneumatic circuits to regulate the rate of activation or exhaust of cylinders and other pneumatic devices.

Ball Valves: Ball Valves provide tight shut-off and characterizable control. They have high range ability due to the design of the regulating element, without the complications of side loads typical of butterfly or globe valves.

Butterfly Valves: Butterfly valves control flow through a circular disc or vane by turning the valve's pivot axis at right angles to the direction of flow in the pipe. They are normally used as throttling valves to control flow

Gas Valves: Gas valves are used to handle and control the flow of gaseous media such as liquefied petroleum and natural gas. They are made of metal or plastic and vary in terms of valve size, pressure rating, number of ports, and flow.

Hydraulic Valves: Hydraulic valves contain and transfer the flow and pressure of hydraulic fluid in hydraulic power systems. They range from simple shutoff valves to precision control valves.

Globe Valves: Globe valves are linear motion valves with rounded bodies, from which their name is derived. They are widely used in industry to regulate fluid flow in both on/off and throttling service.

Control Valves: Control valves or proportional valves are power-operated devices used to modify fluid flow or pressure rate in a process system.

Check Valves: Check valves are self-activating safety valves that permit gases and liquids to flow in only one direction, preventing process flow from reversing. They are classified as one-way directional valves.

Pinch Valves: Pinch valves include any valve with a flexible elastomer body that can be pinched closed, cutting off flow, using a mechanism or fluid pressure.

Needle Valves: Needle valves are small valves used for flow control in liquid or gas services. The fine threading of the stem and the large seat area allow for precise resistance to flow

Pressure Relief Valves: Pressure relief valves are self-actuated safety valves designed to relieve excess pressure upstream from the line

Steam Valves: Steam valves are used to control the flow and pressure level of steam and heated water vapor.

Plug Valves: Quarter-turn plug valves use a cylindrical or tapered plug with a hole in the center to control straight through flow when in the open position.

Sanitary Valves: Sanitary valves are designed for applications requiring clean or sterile processing.

Mixing Valves: Mixing valves combine the flow of two or more inlets into a single outlet for applications such as temperature and concentration control.

Diverter Valves: Diverter valves direct flow from one inlet to one of two or more outlets.

Diaphragm Valves: Diaphragm valves close by means of a flexible diaphragm attached to a compressor.

Water Valves: Water valves are designed to handle and control hot water, cold water, ground water, potable water, salt water and/or wastewater.They are made from metal or plastic.

Plastic Valves: Plastic valves are made from plastic materials and are used in applications that require corrosion resistance and/or chemical handling.

Vacuum Valves: Vacuum valves are used when a vacuum must be maintained in a closed system.

Wafer Check Valves: Wafer check valves are becoming the preferred type of check valve for most applications, due to their compact design and relatively low cost.

Pneumatic Valve Actuators: Pneumatic valve actuators mount on valves and, in response to a signal, move the valve to a desired position using a compressed supply of air.

Electric Valve Actuators: Electric valve actuators mount on valves which, in response to a signal, automatically move to a desired position using an outside power source. Single-phase or three-phase AC or DC motors drive a combination of gears to generate the desired torque level.

Buna-N (Nitrile, NBR): A copolymer of butadiene and acrylonitrile, NBR has excellent resistance to petroleum products, lubricants, and water over a wide temperature range of –10° to +80° C. It does not have good resistance to outdoor exposure to ozone, sunlight, or weather.

Neoprene: Neoprene is unique with its moderate resistance to both petroleum products and oxygen over a wide temperature range of –18° to +90° C. Neoprene is a widely used elastomer for seals with exposure to refrigerants, petroleum oils, and mild acids. Neoprene does not have good resistance to solvents such as MEK and acetone.

EPDM (Ethylene Propylene Diene Monomer): EPDM exhibits strong resistance to ozone, certain hydraulic fluids, brake fluids, steam, and water over a wide temperature range of –20° to +120° C. It has poor resistance to petroleum based fluids, mineral oils, and solvents.

Teflon® (Polytetrafluoroethylene, PTFE): PTFE is a fluorocarbon based polymer and typically is the most chemically resistant of all plastics while retaining excellent thermal and electrical insulation
properties. PTFE also has a low coeffcient of friction so is ideal for many low torque applications. This material is non-contaminating and accepted for use in food services. Although PTFE’s mechanical properties are low compared to other engineered plastics, its properties remain useful over a wide temperature range.

PTFE has outstanding resistance to chemical attack by most chemicals and solvents. PTFE has a temperature rating of -50° to 200° C in valve applications. PTFE, a self-lubricating compound, is most commonly used as a seat material in ball valves and other valves.

RPTFE (Reinforced Polytetrafluoroethylene): This is a compound with a percentage of fiber glass or filler material to provide additional strength, stability and resistance to abrasive wear, cold flow and permeation in molded seats. Reinforcement such as glass fiber
permits applications at higher pressures and temperatures than unfilled PTFE. RPTFE should not be used in applications that attack glass, such as hydrofluoric acid and hot/strong caustics. Temperature range for RPTFE is -160° to +230° C.

Viton® (Fluorocarbon, FKM): Viton possesses a strong resistance to chemicals and air at high temperature applications up to 220° C. It is a durable material, offering excellent seal life in valves. Resistance to mineral acids, oils and many aliphatic and aromatic hydrocarbons is excellent. Viton is high in cost and is used in aircraft, automotive applications where resistance to petroleum oils, silicone fluids, and acids is needed. Viton also has superior chloramine resistance for drinking water applications. 

Nylon (Polyamide): Nylon is one of the first thermoplastics used as a structural part such as  valve bearings. Nylon has excellent resistance to oils and solvents, but limited resistance to alkalis and acids. Its application is limited to a maximum temperature of +120° C.

Delrin® (Polyoxy-methylene): Delrin is very rigid, does not undergo
cold flow, and has an excellent combination of strength, hardness, stiffness, stability, abrasion resistance and low friction. Delrin allows pressures up to 5000 PSI depending on the valve size and seal combination.

PEEK (Poly Ether Ether Ketone): PEEK is a high performance engineered thermoplastic. PEEK is considered a premium seat material that offers a unique combination of chemical, mechanical, electrical and thermal properties. Its excellent water/chemical resistance makes it unaffected by continuous exposure to hot water/steam. PEEK is good for temperatures of -20° to +260° C. PEEK is non-porous, has high strength for high pressure applications and is suitable for high corrosion environments. 



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