Elastomers and Plastics; Sales

A consulting engineer is specifying a butterfly valve for a municipal drinking water pipeline. Which elastomer would you recommend?

EPDM
• Standard choice for municipal water
• Excellent with water, steam, ozone, and chloramines
• Common in butterfly valve seats, gate valve wedges, and O-rings
• Low cost ($)
• Avoid petroleum oils and fuels

A customer asks if EPDM is suitable for diesel fuel service.

No.
Petroleum oils, gasoline, diesel, and many solvents attack EPDM.
Recommend Buna-N or Viton depending on temperature.

Why has EPDM become one of the most common elastomers in municipal water systems?

Because it has excellent resistance to chloraminated drinking water, steam, ozone, and weathering.

Relative price of EPDM?

Low ($)
One of the least expensive engineering elastomers.

A valve will seal hydraulic oil and diesel fuel. Which elastomer is your first recommendation?

Buna-N (NBR)
• Excellent for petroleum products
• Excellent for lubricants
• Excellent for hydraulic systems
• Low cost ($)

Would you specify Buna-N for outdoor ozone exposure?

No. Buna has poor resistance to ozone, sunlight, and weathering.

Where is Buna-N commonly used besides valves?

Hydraulic system O-rings. This is one of the easiest ways to remember its strength.

Relative price of Buna-N?

Low ($)

Customer needs an elastomer for hot petroleum service. Recommendation?

Viton
• Excellent oil resistance
• Excellent fuel resistance
• Better high-temperature capability than Buna
• Premium material ($$)

When would you choose Viton over Buna?

When the application involves higher temperatures, more aggressive chemicals, or petroleum products.

Would you automatically choose Viton for municipal drinking water?

Usually no. EPDM is generally preferred unless another service condition requires Viton.

An engineer needs resistance to strong acids, bases, and hot oil. Recommendation?

Aflas
• Strong acids
• Strong bases
• Excellent oil resistance
• Continuous service to about 450°F
• Premium material ($$)

Relative price of Aflas?

$$
Only specify when the application justifies the added cost.

Nothing else survives the customer's chemical process. Which elastomer comes to mind?

Chemraz
• Extremely broad chemical resistance
• Excellent high-temperature steam resistance
• Up to about 600°F
• Premium material ($$)

When should you recommend Chemraz?

Only when lower-cost elastomers cannot survive the service. Specifically used in high temperature steam applications (up to 600F). Avoid overspecifying because of its cost. Chemraz is special because of how it is built. In chemistry, it belongs to a group of materials where all the "hydrogen" atoms are swapped out for "fluorine". This complete replacement makes it highly resistant to almost all chemicals

How is Kalrez different from Viton?

Kalrez provides broader chemical resistance and higher temperature capability than Viton for the most demanding applications.

An application involves harsh petrochemical solvents and very high temperatures. Recommendation?

Markez
• Broad chemical resistance
• High-temperature capability (around 600°F)
• Premium sealing material

When is Hypalon a good choice?

When resistance to acids and ozone is important.
Typical temperature range: about -50°F to 200°F.

An engineer needs a high-pressure valve seat rather than a flexible rubber seal. Recommendation?

Devlon
• Engineering thermoplastic
• Excellent wear resistance
• Excellent corrosion resistance
• Pressure capability up to about 6000 psi
• Temperature range about -50°F to 250°F

What industry commonly uses Devlon seats?

Oil & gas and other high-pressure valve applications.

Aflas

Fluoroelastomer compound that has excellent heat resistance with continues service temperature capability of 450°F and good chemical resistance, including resistance to strong acids and bases. Also has excellent oil resistance.

Buna-N, (Nitrile, NBR, HNBR)

Excellent resistance to petroleum products, lubricants, and water over a wide temperature range of -50 to 200°F. Nitrile is a widely used elastomer for hydraulic system o-rings. Does not have good resistance to outdoor exposure to ozone, sunlight or weather. High Nitrile Buna-N (HNBR) is formulated for high strength and resistance to Hydrogen Sulfide (wastewater gas) and other harsh fluids.

Chemraz

High temperature perfluoroelastomer with superior physical properties and chemical resistance. Compound excels in dynamic applications and exhibits unparalleled performance in high temperature steam. Temperature range is from 0°F to 600°F

Devlon

The toughest and hardest wearing thermoplastic available. Designed for the valve industry as a seat material to provide wide temperature and pressure range. Well documented resistance to chemical and corrosion attack, useful in oil and gas applications. Pressures up to 6000psi and temperature from -50 to 250°F

EPDM (Ethylene Propylene Diene Monomer)

Strong resistance to ozone, certain hydraulic fluids, brake fluids, steam, and water over a wide temperature range -50 to 250°F. Has gained increased use in municipal water industry because of its resistance to water disinfect w/ chloramines. Poor resistance to petroleum-based fluids, mineral oils, and solvents.

Hypalon (Chlorosulfonated Polyethylene, CSM)

Similar to neoprene in chemical resistance and useful in range of -50 to 200°F for acid and ozone resistance.

Kalrez (Perfluoroelastomer)

Similar to Viton but is formulated for long-term exposure to the harshest chemical environments and temperatures above 600°F. Combines the chemical and heat resistance of Teflon, with the flexible stretchy properties of standard rubber.

Markez

High preformance perfluoroelastomer compound that offers a broad chemical and temperature resistance up to 600°F. For demanding industries, like Petrochemical where harsh solvents are required. Temperature range is -5°F to 600°F

Natural Rubber (Natural Polyisoprene, NR)

Excellent wear properties and resistance to brake fluid, water, sewage, but not petroleum products. Economical, used in valves for abrasion resistance. Mostly replaced with synthetic elastomers for industrial seals.

Neoprene (Chloroprene, CR)

One of the first low cost elastomers, unique with its moderate resistance to both petroleum products, UV rays/ozone and oxygen over a wide temperature range of -50 to 200°F. Widely used elastomer with exposure to refrigerants, petroleum oils, and mild acids. Does not have good resistance to solvents such as MEK and acetone.

Nylon (Polyamide)

Thermoplastic used as rubber chords, and valve bearings. Nylon has excellent resistance to oils and solvents, but limited resistance to alkalis and acids. Maximum temperature is 250°F

PEEK (Poly Ether Ether Ketone, CFFP)

High performance engineered thermoplastic. PEEK is considered a premium seat material that offers a unique combination of chemical, mechanical, electrical and thermal properties. Excellent water/chemical resistance makes it unaffected by continuous exposure to hot water/steam. PEEK is good for temperatures of -70°F to 500°F. PEEK is non-porous, high strength for high pressure applications and suitable for high corrosion environments. Carbon Fiber Filled PEEK (CFFP) is reinforced to withstand up to 600°F

RPTFE (Reinforced Polytetrafluoroethylene)

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 is -320 to 450°F

Viton (Fluorocarbon, FKM, FKM AED, FF200)

Possesses a strong resistance to chemicals and air at high temperature applications up to 400°F. Viton is high in cost used where petroleum oils, silicone fluids, and acids is needed. Viton also has superior chloramine resistance for drinking water applications. FKM Anit-Explosive Decompression (AED) formulation has a structure that reduces gas permeation in extreme pressure service so that the sudden decompression in gas pressure will not cause damage to the seal. The Viton FF200 formulation is designed to withstand long term exposure to heat at 625°F.