Plastic Body Materials

IMPORTANT NOTE There are many variables that affect success or failure of a particular material with any given chemical, including concentration, temperature, and the specific compound of the plastic. A material deemed suitable for a specific application is not necessarily suitable for every application, nor that every version of that material is suitable. Plastic compounds vary between manufacturers, and the design of a valve may affect compatibility as well.

The information presented below is generally accurate, but your application may have variables that affect the performance of the material. Plast-O-Matic presents this information and any links solely as a convenience. Your distributor can help with compatibility questions, and you are welcome to contact our Technical Group at (973) 256-3000, but the ultimate determination of suitability of any information, product or material, for use contemplated by the user, the manner of that use, and whether there is any infringement of patents, is the sole responsibility of the user. To the extent that any hazards are listed, we neither suggest nor guarantee that such hazards are the only ones that exist.

It is important to note that any information obtained should be used only as a guide. In many cases a physical test of the material under operating conditions is the only way to ensure the success of a particular material for that application.

GEON^® PVC (Polyvinyl Chloride Type 1, Grade 1)

This material has been successfully used for over 30 years in such areas as chemical processing, waste and wastewater treatment, industrial plating and deionized water lines and is the most frequently specified of all thermoplastic materials. PVC provides excellent chemical resistance to a wide variety of acids, alkalies, salt solutions and many other chemicals. It is attacked, however, by some solvents, aromatics and chlorinated organic compounds. The maximum service temperatureof PVC is 140°F (60°C). Plast-O-Matic uses 100% Geon brand PVC in the manufacture of its products.

PVC is joined by solvent cementing, threading or flanging.

Please click here for chemical resistance information specific to Geon PVC.
(Acrobat "PDF" document prepared by Geon. Plast-O-Matic does not guarantee chemical compatibility; end user is responsible for ultimate determination of chemical compatibility. It is important to note that any information obtained should be used only as a guide. In many cases a physical test of the material under operating conditions is the only way to ensure the success of a particular material for that application.)

CORZAN^® CPVC (Chlorinated Polyvinyl Chloride) Type 4. Grade 1

This material's physical properties (at 73°F or 23°C) and chemical resistance are very similar to those of PVC. Its major advantage over PVC is the ability to handle hot corrosive liquids in service temperatures up to 180°F (82°C).

The molded version of Corzan is Temprite^®, which like Corzan, is manufactured by Lubrizol. Plast-O-Matic uses 100% Corzan brand CPVC in the manufacture of its products.

CPVC is joined by solvent cementing, threading, or flanging. It must be done by a professional, properly trained in joining CPVC.

Please click here for chemical resistance information specific to Corzan CPVC.
(External website hosted by Lubrizol. Plast-O-Matic does not guarantee chemical compatibility; end user is responsible for ultimate determination of chemical compatibility. It is important to note that any information obtained should be used only as a guide. In many cases a physical test of the material under operating conditions is the only way to ensure the success of a particular material for that application.)

Please note that Corzan CPVC is incompatible with a number of popular pipe joint compounds. Use the Lubrizol link above to investigate compatibility. Plast-O-Matic does not guarantee this information.

Polypro (Polypropylene) Type 1

Natural Polypropylene -- Homopolymer polypropylene is a thermoplastic with low specific gravity and excellent chemical resistance to a wide range of acids, alkalies and organic solvents. It is also used in deionized water distribution. It is not recommended for use with strong oxidizing acids, chlorinated hydrocarbons and aromatics. The polypropylene used by Plast-O-Matic, unless indicated as "GPP" or "Glass-Filled," is 100% natural, virgin (unprocessed) resin with no pigments or other fillers whatsoever. These high purity properties make Natural Polypro an ideal altervative to PTFE and PVDF in many instances. The maximum service temperature is 180°F (82°C). Although polypropylene has a low melting point, it offers excellent structural rigidity.

Polypropylene is joined by heat fusion, threading or flanging.

Glass-Filled Polypropylene -- The addition of glass fibers to Polypropylene provides greater mechanical strength and therefore higher pressure & temperature capabilities. This type of polypropylene generally has a small amount of pigmentation.

Glass-filled polypropylene is joined by heat fusion, threading or flanging.

Fluoropolymers

Fluorinated thermoplastics such as PTFE, PVDF, PFA, etc. offer significant advantages in terms of chemical resistance and lubricity. You may be familiar with Kynar®, which is the brand name of certain PVDF fluoropolymers manufactured by Arkema. Plast-O-Matic uses 100% Kynar brand PVDF in the manufacture of valve bodies and machined parts. Plast-O-Matic is a licensed reseller of Kynar. All other fluoropolymer items are identified by generic names only.

KYNAR^® PVDF (Polyvinylidene Fluoride)

This fluoropolymer material has superior chemical and abrasion resistance, mechanical strength and temperature capabilities in comparison to all other thermoplastic materials. It offers substantially greater strength and wear resistance over other common fluoroplastics (PTFE, PFA, etc.). It is chemically resistant to most strong acids, mild alkalies, organic solvents, wet or dry chlorines, bromine and other halogens and is also used extensively in the conveyance of high purity deionized water due to its absence of colorants or additives. Because of its outstanding mechanical properties and that it is similarly impervious and non-leaching, PVDF is sometimes used for certain parts in polypro and PTFE valves for design strength. You should check the specifications, or consult factory if this is a concern.

The maximum service temperature is 280°F (138°C); melting point is 170°C.

Kynar PVDF is joined by heat fusion, threading or flanging.

Please click here for information specific to Kynar PVDF.
(Document provided by Arkema. Plast-O-Matic does not guarantee chemical compatibility; end user is responsible for ultimate determination of chemical compatibility. It is important to note that any information obtained should be used only as a guide. In many cases a physical test of the material under operating conditions is the only way to ensure the success of a particular material for that application.)

Please click here for Kynar PVDF ASTM E84, FM 4910, UL 2360 & ASTM D2863 flame/burn test results.
Please click here for Kynar PVDF Private & Regulatory Approvals NSF, FDA, USDA, 3A, USP, and Kosher certification.
(Documents provided by Arkema. Plast-O-Matic does not guarantee chemical compatibility; end user is responsible for ultimate determination of chemical compatibility. It is important to note that any information obtained should be used only as a guide. In many cases a physical test of the material under operating conditions is the only way to ensure the success of a particular material for that application.)

PTFE (Polytetrafluoroethylene)

Many people mistakenly refer to PTFE as "Teflon," which is actually a registered trademark of DuPont, and is a brand that covers many types of fluoropolymers.

PTFE is practically insoluble and chemically inert to most chemicals and solvents. It is widely used in the handling of high purity deionized water. While PTFE is capable of 500°F (260°C) Plast-O-Matic does not recommend its use in valve designs beyond 300°F (149°C).

The main advantages of PTFE in valve design is that it is ideal for both high purity and highly corrosive applications, because it is virtually impervious to corrosion, and is extremely low in terms of leaching. It is also excellent for valve parts due to its low frictional properties. Its limitations are that it will "cold flow," i.e., PTFE can be reshaped after contact with other parts. It is also not ideal for higher pressure threaded connections on larger pipe sizes.

PTFE is joined by threading or flanging.

PFA (Perfluoroalkoxy resin)

PFA is a melt processible fluoroplastic equal to PTFE in chemical resistance. It is used for many valve parts such as bellows in solenoid valve, and encapsulation of springs when used as a wetted part. PFA is also used for molded body valves, and although the PTFE valve has a different appearance and translucence, the PTFE valve can be used in place of a PFA valve with no change in chemical resistance. Both materials are equally inert and have the same dielectric constant.

FEP (Flourinated ethylene propylene)

FEP is a relatively soft fluoroplastic, with the same inert, low dielectric, and low friction properties of PTFE and PFA. It does not offer quite the same mechanical properties at elevated temperatures as PTFE and PFA.

NORYL^® PPO (Type GFN1; Polyphenylene ether + Polystyrene, 10% glass fiber filled)

This modified polyphenylene blend offers excellent physical properties, low moisture absorption, and in-service temperatures up to 180°F (82°C). Plast-O-Matic uses Noryl GFN1 as a body material in level and flow switches. Noryl is joined by threading, and provides excellent chemical resistance to a wide variety of acids, alkalies, salt solutions and many other chemicals. It is attacked, however, by petroleum products, as well as some solvents, aromatics and chlorinated organic compounds.

Please click here for a chemical resistance chart. Note this is information supplied by the resin manufacturer. Plast-O-Matic does not guarantee chemical compatibility; end user is responsible for ultimate determination of chemical compatibility. It is important to note that any information obtained should be used only as a guide. In many cases a physical test of the material under operating conditions is the only way to ensure the success of a particular material for that application.

PYREX^® (borosilicate glass)

This low alkali glass is used on sight glasses and level indicators. It resists attack from most bases and acids with the exception of hydrofluoric acid and sodium hydroxide. It is the same material used in glass piping systems in the food, beverage, chemical, and pharmaceutical industries.

Please click here for a material safety data sheet
(External website hosted by Corning Glass. Plast-O-Matic does not guarantee chemical compatibility; end user is responsible for ultimate determination of chemical compatibility. It is important to note that any information obtained should be used only as a guide. In many cases a physical test of the material under operating conditions is the only way to ensure the success of a particular material for that application.)

IMPORTANT: It should be noted that plastic pipe and fittings have varying resistance to weathering. PVC for example undergoes surface oxidation and embrittlement with exposure to sunlight over a period of several years. Also, ultraviolet sterilizers for killing bacteria in deionized water are becoming common and the intense light generated will, over time, stress-crack PVC piping & fittings that are directly connected to the sterilizer.

Elastomers

Buna-N (Nitrile Rubber)

This elastomer is recommended for general purpose sealing of water, petroleum oils, solvents and some alkalies. It is superior to most other elastomers with regard to compression set, abrasion and tear resistance. The maximum service temperature of Buna-N is 200°F (94°C). In 1999 Plast-O-Matic began phasing out standard use of Buna-nitrile in favor of EPDM (see below), with the exception of seals in air chambers and those used in oil-based applications when ordered specifically with Buna seals.

EPDM (Ethylene Propylene Diene Monomer)

EPDM, commonly known as ethylene-propylene rubber, is an olefinic thermoplastic elastomer with good temperature performance and good compression and tensile set. This elastomer has good abrasion and tear resistance while offering excellent chemical resistance to a variety of acids, alkalines, alcohols and oxidizing chemicals. However, it is susceptible to attack by oils. The maximum service temperature of EPDM is 250°F (121°C). EPDM has a low specific gravity, usually 0.8 to 1.0, and consequently offers low part weight.

Viton^® (Vinylidene Fluoride - Hexafluoropropylene) Fluorocarbon

(Viton® is a brand name for fluoroelastomers manufactured by DuPont Dow Elastomers.) This fluoroelastomer provides chemical resistance to a wide range of chemicals, concentrations and temperatures involving mineral acids, salt solutions, chlorinated hydrocarbons and petroleum oils. Although its chemical compatibility to most acids is excellent it can be mechanically swollen by some. In such cases Plast-O-Matic uses a specially cured Viton® to reduce the swell factor encountered with standard Viton®-A.The maximum service temperature of Viton® is 300°F (149°C).

Please click here for information specific to Viton®.
(Document from DuPont Dow Elastomers. Plast-O-Matic does not guarantee chemical compatibility; end user is responsible for ultimate determination of chemical compatibility. It is important to note that any information obtained should be used only as a guide. In many cases a physical test of the material under operating conditions is the only way to ensure the success of a particular material for that application.)

PTFE (Polytetrafluoroethylene)

PTFE is not an elastomer but has superior qualities for use in plastic valves as a diaphragm or bellows seal. It is frequently used as an "encapsulation" material for rubber o-rings, steel springs, etc. where the properties of the inner material are required but cannot contact the liquid. PTFE shafts in conjunction with elastomer seals are also used successfully in Plast-O-Matic products. The most prevalent use of PTFE is in the ball valve, where the sealing "seats" are PTFE (backed with elastomer seals) and various bearings etc. are PTFE. In addition to chemical inertness and exceptionally low coefficient of friction, PTFE provides non-sticking, long cycle life capabilities.

Fluorosilicone Rubber

This elastomer is noted for its retention of flexibility, resilience and tensile strength over a wide temperature range. It is not, however, noted for its chemical resistance.

Kalrez^® & Chemraz^® (Perfluoroelastomer)

(Kalrez is a perfluoroelastomer manufactured by DuPont Dow Elastomers; Chemraz is a perfluoroelastomer manufactured by Greene Tweed.) These elastomers combine the chemical resistance of Viton and fluoropolymers, making it far superior to most other elastomers. However, because of its high cost it is only used where absolutely required. It is only available inO-ring and sheet form so it cannot be used with all valve designs.

Aflas^® TFE (Tetrafluoroethylene/propylene dipolymer)

Aflas is a brand name manufactured by 3M. Aflas is an alternative to perfluoroelastomers in many applications. It offers excellent chemical and electrical resistance, and service temperatures to 400 degrees F (204 C) It is especially resistant to newer specification automotive lubricants, battery acids, jet and rocket fuels, oilfield applications, and more. The most common use in plastic valves is in ozone water treatment systems, where it is excellent.

Other materials found in plastic valves & controls

While valve bodies are generally either thermoplastics or fluoroplastics, and seals are generally thermoplastic elastomers, many plastic valves use metals in some fashion. In a properly designed valve, these metals have no contact with process media and minimal external exposure. Valve bodies that are not threaded together require a fastener of some type; the best combination of strength and resistance is a stainless steel fastener. In many cases valve bodies are threaded together to eliminate the need for external fasteners, but in certain types of valves the fastener improves the design via added strength and rigidity. Pressure valves, for instance, tend not to perform as well if the body is threaded from two separate parts (note that Plast-O-Matic's pressure valves without fasteners have a unibody design and use separate parts specifically for threading).

Springs are used in fail-safe and automatic pressure valves (relief valves, pressure regulators, etc.) and are generally some type of steel; often stainless steel or other steel, determined by the spring rate and other specific properties required by the valve design and function.

Solenoid Valves use many other materials. In a good plastic valve design, these materials are intentionally isolated from any contact with liquid (unless specified in the design) but can have exposure to atmosphere. Solenoid core tubes frequently include stainless steel, stainless steel with some ferrous properties, sometimes copper, silver, and other metal parts. Solenoid coils are generally some type of polyester and another plastic material. Some solenoid coils have metal housings. It is important to check the specifications for each valve to ensure that materials are compatible with your process and/or environment.

Acrylics are used in valve and piping components design where visual verification is desired. Sight glasses and level indicators use acrylic and many shutoff valves also use acrylic. It offers excellent abrasion resistance, and excellent optical quality. It also resists UV light.

Epoxy and other potting materials are used in certain valves and system controls to isolate switches, sensors, etc. These are often limited to atmospheric exposure, but in some products, epoxies are exposed to liquid. They generally perform as well as typical piping polymers, although some epoxies are susceptible to chromic acids, high concentrations of nitric acid, and a number of plating solutions such as copper sulfate bath, nickel plating bath, fluoride baths, and others. Flow Switches have wetted Epocap® brand epoxy and compatibility can be checked by clicking here and referring to the right hand column titled "epoxy." As with any material, controlled testing under your application parameters is the only way to truly determine chemical compatibility.

IMPORTANT NOTE There are many variables that affect success or failure of a particular material with any given chemical, including concentration, temperature, and the specific compound of the plastic. A material deemed suitable for a specific application is not necessarily suitable for every application, nor that every version of that material is suitable. Plastic compounds vary between manufacturers, and the design of a valve may affect compatibility as well.

Geon® is a trademark of the Geon Co., Corzan® and Temprite® are trademarks of Noveon, Inc., Kynar® is a trademark of Arkema,
Viton® and Kalrez® are trademarks of DuPont Dow Elastomers,
Pyrex® is a trademark of Corning Glass, Aflas® is a trademark of 3M, Chemraz® is a trademark of Greene-Tweed,
Epocap® is a trademark of Royal Adhesives & Sealants; Noryl® is a trademark of Saudi Basic Industries Corporation.

For additional information, please return to the Plast-O-Matic Tech Info Center.