The type of media being controlled by the solenoid valve will have a direct effect on its ability to function properly. The purpose of this guide is to briefly introduce some materials commonly used when selecting a solenoid valve for specific applications. The guide includes Descriptions, Key Uses, Features and Limitations. The Chemical Compatibility Table lists 31 commonly used materials and rates their performance when exposed to various media.

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Delrin (Acetal)


• Standard Color: White
• Description: Acetals are polymers of formaldehyde which technically are called polyoxymethylenes. Acetals are widely used engineering thermoplastics with high load-bearing characteristics and low coefficient of friction.
• Key Uses: Industrial/mechanical products, appliances and plumbing. Based on excellent performance of Acetal copolymers in water at temperatures up to 212 F, they are widely used to mold faucet under-bodies, shower heads, housings for pumps and filters, hydraulic valves and fittings. Maximum Working Temperature: +212 F
• Features: Acetals are available in several specific grades. Easy-flow acetals which can be used in very thin-walled injection moldings, lubricated for low coefficient of friction and glass reinforced for strength and dimensional stability to name a few.
• Limitations: Acetals are attacked by ultraviolet radiation, becoming brittle with long term exposure to sun light. UV-stabilization can provide significant improvements.


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Nylon


• Standard Color: Neutral, Black
• Description: Nylons, or polyamides, are melt processable thermoplastics that contain an amide group as a recurring part of the chain. The first and largest volume of the engineering thermoplastics, they offer a combination of properties including high strength even at elevated temperatures, ductility, wear and abrasion resistance and good chemical resistance.
• Key Uses: Nylons are used in virtually every industry and market. Transportation represents the largest single market for unreinforced and glass-reinforced nylons ranging from electrical connectors and wire jackets to engine fans and brake and power steering reservoirs.
• Maximum Working Temperature: +266 F
• Features: The mechanical properties of nylons are strength, stiffness and toughness and the combination thereof. Fiber reinforcement increases stiffness, strength and heat resistance. Excellent chemical resistance to hydrocarbon fuels, lubricants and various organic solvents is a distinguishing feature of nylons compared to other engineering plastics.
• Limitations: Nylons are attacked by strong acids, oxidizing agents and concentrated solutions of certain salts. Absorbed moisture acts as a plasticizer and causes slight dimensional changes that must be considered in design.


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PVC


• Standard Color: Gray
• Description: PVC is a vinyl-based resin and is produced by an oxyhydrochlorination process. It is the most versatile of all plastics because of its ability to be used to manufacture products ranging from heavy-walled pressure pipe to thin, crystal clear food packaging. PVC is easily machinable and can be injection molded.
• Key Uses: Traditional uses for PVC compounds are hot- and cold-water distribution piping and industrial liquid handling pipe, fittings, hydraulic valves and the like.
• Maximum Working Temperature: +219 F
• Features: The chemical resistance of PVC has prompted its use in industrial liquid handling, especially for high temperature liquids in paper and pulp operations, and acids and bases in plating and electrochemical operations.
• Limitations: PVC is highly flammable and subject to rigorous protective measures because of health hazards.


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Stainless Steel


• Description: Stainless steels are high-alloy steels and have superior corrosion resistance to the carbon and conventional low-alloy steels because they contain relatively large amounts of chromium. In the broadest sense, the standard stainless steels can be divided into three groups based on their structures: austenitic (300 Series), ferritic (400 Series), and martensitic.
• Key Uses: Applications for 300 series stainless steels include highly corrosive environments. Spartan utilizes 300 stainless steel in production of valve bodies where control of hydraulic corrosive media and compatibility is an issue.
  
  Applications for 400 series stainless steels include magnetic solenoid plungers and stops.
• Features: 300 series stainless steels are austenitic and are nonmagnetic in the annealed condition. They combine outstanding corrosion and heat resistance with good mechanical properties over a broad temperature range.
  
  400 series stainless steels are ferritic grades and are always magnetic and contain chromium but no nickel. They combine corrosion and heat resistance with moderate mechanical properties.
• Limitations: The ferritic grades are generally restricted to a narrower range of corrosion conditions than the austenitic grades.


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Cast Bronze and Brass


• Description: Bronze and brass are high copper alloys which are highly malleable, and are of the first to be found and utilized. These alloys are widely used because of their excellent electrical and thermal conductivities, outstanding resistance to corrosion, ease of fabrication, and a broad range of obtainable strengths and special properties.
• Key Uses: Safety tools, molds for plastic parts, cams, bushings, bearings, valves, pump parts and gears.
• Features: There are almost 400 commercial copper and copper-alloy compositions available from mills as wrought products (rod, plate, sheet, strip, tube, pipe, extrusions, foil, forgings and wire) and from foundries as castings.
• Limitations: Bronze and brass are restricted to a narrow range of corrosion conditions as the copper tends to oxidize and sometimes dissolve in some damp and harsh chemical environments.


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Aluminum


• Description: Pure aluminum is a silver-white metal characterized by a slightly bluish cast. It has a specific gravity of 2.70, resists the corrosive effects of many chemicals and has a malleability approaching that of gold. When alloyed with other metals, numerous properties are obtained which make these alloys useful over a wide range of applications.
• Key Uses: The automotive industry is the prime user of aluminum alloys for wheels and wheel covers and other light weight and decorative trim. It is also used in the pneumatic industry to produce light weight valve bodies and components.
• Features: When aluminum surfaces are exposed to the atmosphere, a thin invisible oxide forms immediately which protects the metal from further oxidation. This self-protecting characteristic gives aluminum its high resistance to corrosion.
• Limitations: Although the metal can safely be used in the presence of certain mild alkalies with the aid of inhibitors, in general, direct contact with alkalies should be avoided. Direct contact with certain other metals should be avoided in the presence of electrolyte; otherwise galvanic corrosion of aluminum mat takes place in the vicinity of the contact area. The use of a bituminous paint coating or insulating tape is recommended.


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Buna N


• Standard Color: Black
• Description: Buna is the most widely used elastomer. It combines excellent resistance to petroleum-based oils and fuels, silicone greases, hydraulic fluids, water and alcohols, with a combination of working properties such as low compression set, high tensile strength, and abrasion resistance.
• Key Uses: Oil resistant applications of all types. Low temperature military uses. Fuel systems. Can be compounded for FDA applications.
• Temperature Range: -40 F to +250 F (Dry Heat Only)
• Features: Increasing acrylonitrile content gives Buna its better resistance to petroleum-based oils and hydrocarbon fuels, enhancing resistance to the degrading effects of heat, at a cost of reduced low temperature performance.
• Limitations: Precautions should be taken to avoid exposure of Buna to such highly polar solvents as acetone, MEK, chlorinated hydrocarbons and nitro hydrocarbons, which are known to cause rapid deterioration.


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Aflas^®


• Standard Color: Black
• Description: A copolymer of tetrafluoroethylene and propylene, Aflas exhibits excellent chemical resistance properties.
• Key Uses: Seals for oil field, industrial and chemical applications.
• Temperature Range: +60 F to +400 F (Dry Heat Only)
• Features: Aflas features good resistance to petroleum fluids; steam; a number of acids and alkalies; amines (anti-freeze); phosphate esters and brake fluids. It has generated considerable interest as a seal material for oil field, industrial and chemical applications.
• Limitations: Compression set of 52% after 30 days at 400 F may be considered too high for some sealing applications.


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Chemraz^®


• Standard Color: Black
• Description: A perfluoroelastomer possessing exceptional resistance to degradation by aggressive fluids and/or gases.
• Key Uses: Severe chemical exposure and high temperatures. Seals for chemical processing & transportation.
• Temperature Range: -35 F to +500 F (Dry Heat Only)
• Features: Chemraz parts combine the high temperature toughness of a fluorocarbon elastomer, with the chemical inertness of Teflon. As a group, parts resist attack by nearly ALL chemical reagents and provide long term service in virtually ALL chemical and petrochemical process streams.
• Limitations: Chemraz parts can be made to significantly swell upon exposure to some fluorinated solvents; fully halogenated freons; and uranium hexafluoride.


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EPDM (Ethylene-Propylene)


• Standard Color: Black
• Description: A copolymer of ethylene and propylene. Ethylene propylene has gained acceptance for its excellent ozone and chemical resistance.
• Key Uses: Outdoor weather resistant uses. Hydraulic and automotive brake systems. Water appliances.
• Temperature Range: -60 F to +300 F (Dry Heat Only)
• Features: EPDM features good resistance to polar solvents such as MEK and acetone. It is also highly recommended for effective resistance to steam (to 400 F); hot water; silicone oils and greases; dilute acids and alkalies; alcohol and automotive brake fluids.
• Limitations: With the exception of resistance to polar solvents, EPDM is not recommended for its overall solvent resistance.


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Fluorocarbon (Viton)


• Standard Color: Black
• Description: Combining high temperature resistance with outstanding chemical resistance, Fluorocarbon-based compounds are the ideal seal material.
• Key Uses: High temperature/low compression set applications. Wide chemical exposure situations.
• Temperature Range: -20 F to +400 F (Dry Heat Only)
• Features: Fluorocarbons are highly resistant to swelling in gasoline and gasoline/alcohol blends, as well as resistant to the degrading effects of U.V. light and ozone.
• Limitations: Fluorocarbons are not recommended for exposure to ketones. They are also not recommended for situations requiring good low temperature flexibility.


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Neoprene


• Standard Color: Black
• Description: Neoprene is a homopolymer of chloroprene and is one of the earliest of the synthetic materials to be developed as an oil-resistant substitute for Natural Rubber.
• Key Uses: Recommended for exposure to weathering. Preferred sealing material for refrigeration industry. FDA approved for food and beverage industry use.
• Temperature Range: -45 F to +250 F (Dry Heat Only)
• Features: Neoprene has a good resistance to ozone, sunlight and oxygen aging; relatively low compression set; good resilience; and reasonable production cost.
• Limitations: Neoprene is generally attacked by strong oxidizing acids, esters, ketones, chlorinated, aromatic and nitro hydrocarbons.


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