Plastic Information: Pressure and Temperature Rating

Information on corrosion resistant plastics used by Delta Controls.

Materials Commonly Offered By Delta Controls

Delta Controls offers many of its instruments and controls with plastic solid or laminated components. These modern materials have many advantages over older metal and ceramic technologies. Increased corrosion resistance, longer service life, and lower costs of ownership are prime examples.

PVC (Polyvinyl Chloride)

PVC is the most commonly specified and used plastic material. It has been successfully used in piping systems for over 30 years. It handles a great variety of services; some typical ones are: municipal water lines, plating systems, irrigation distribution, and deionized water. This material is generally quite strong and very corrosion resistant. It withstands chemical attack from most acids, many alkalis, salt water, chlorinated water, turpentine, and crude oil. It is rapidly attacked by polar solvents (MEK and other ketones) and aromatic hydrocarbons. PVC shows heat deflection at +180 °F (+85 °C). Its use as a plant piping material is generally limited to operating temperatures between +20 °F and +140 °F (+5 °C to +60 °C).

PP (Polypropylene)

PP is polyolefin material with good resistance to organic solvents as well as to most acids and bases. The ability to withstand both solvents and corrosion make it useful for handling crude oil, plant recycle waste, and other services which contain mixtures of solvents, oils and corrosive chemicals. Its usage is normally limited to temperatures between -10 °F and +200 °F (-20 °C to +95 °C).

RUBBER (“O” Rings and Gaskets)

Buna-N (or Nitrile) is a general use rubber for services up to +225 °F (+110 °C). Silicon rubber is a heat resisting elastomer suitable for steam and similar services up to +400 °F (+205 °C). Viton (DuPONT trademark) is a fluorocarbon elastomer with excellent chemical resistance to +500 °F (+260 °C). Kalrez (DuPONT trademark) is a perfluoro carbon elastomer with superb chemical resistance to +600 °F (+315 °C).

PVDF (Polyvinylidene Fluoride)

PVDF is a strong, tough, and abrasion resistant thermoplastic. It is chemically inert to most strong acids, and alkalis. It is suitable for handling halogens, such as bromine and chlorine, either wet or dry. Other services include butyl acetate, carbon disulfide, 50 percent chromic acid, formic acid, and 70 percent nitric acid. It is not suitable for solvents such as acetone, ethyl acetate, and methyl ethyl ketone. PVDF shows heat deflection at +350 °F (+175 °C). It should not be used in piping systems at temperatures higher than +280 °F (+140 °C) or lower than -40 °F (-40 °C).

PTFE (Polytetrafluoroethylene)

PTFE displays excellent corrosion resistance. It is chemically inert to almost all acids, bases, and solvents. A notable exception is the alkali metal sodium. PTFE cannot be joined to itself or other materials by welding or normal gluing. It is soft, easy to abrade, and cold flows readily. The primary use for this material is in seals, as a process equipment liner, and as an “anti-stick” coating. Its useful temperature range extends from -450 °F to +500 °F (-230 °C to +260 °C)

EPOXY (Two Part Resins)

Epoxy resins are a blend of materials that strongly bond to other materials, and are set by a catalyzed chemical reaction. The resulting hard amorphous mass is strong, highly corrosion resistant, and operates over a wide range of temperatures. Pure resins usually serve as high quality glues. Glass fibers and filaments bonded together with epoxy resins are used to produce process piping systems which operate from -20 °F to +300 °F (-28 °C to +148 °C). This material handles most acids, bases, and solvents; examples are food and urea.

Protective Encapsulants

Epoxies, Urethane, and Silicon Rubber are useful to protect field mounted electronic circuitry from moisture, corrosion, and vibration. These materials are also used to encapsulate most Intrinsically Safe transmitters.