Valve Material Selection Guide

For Commonly Used Fluids

NOTE: All orders entered using this Guide must state actual fluid, fluid pressure and fluid temperature of the application. Actual fluid is extremely important when elastomer options are specified because other substitutions may be required.

ASCO valves are available to control many acids, alcohols, bases, solvents, and corrosive gases and liquids. Modified or special designs are sometimes required depending upon the application.

Corrosion occurs either as a chemical or electrochemical reaction. Therefore, consideration must be given to both the galvanic and electromotive force series, as well as to pressure, temperature, and other factors that might be involved in the application.

This Guide provides information on types of valves that are available for most common corrosive and noncorrosive gases and liquids. For applications where abnormal conditions exist and for other fluids, consult your local ASCO office giving full details on operating conditions.

This Guide is not intended as a specific recommendation; factors beyond our control could affect valve operation or materials.

General Information on Elastomer Materials

BUNA "N"

Buna "N" is commonly referred to as a nitrile rubber, and is ASCO's standard synthetic elastomer for accomplishing resilient-type seating or sealing. It has excellent compatibility for most air, water and light oil applications. It has a useful temperature range of 0F. ( - 18°C.) to 180°E (82°C.).

NEOPRENE

Neoprene is principally used as an external seal in refrigeration applications. It is also utilized for oxygen service. It has a useful temperature range of 0°E ( - 18°C.) to 180°E (82°C. ).

ETHYLENE PROPYLENE

Ethylene propylene is selected for applications which are above the Buna "N" temperature range such as handling hot water and steam. Ethylene propylene has an extremely wide range of fluid compatibility but has the distinct disadvantage that it cannot be used with petroleum-based fluids or fluids so contaminated (such as lubricated air). It has a useful temperature range of—10°E ( - 23°C.) to 300°E ( 149°C. ).

Viton(R)*/FLUOREL,** ETC.

Viton(R) is a fluorocarbon elastomer which was primarily developed for handling hydrocarbons such as jet fuels, gasolines, solvent, etc., which normally caused detrimental swelling to Buna "N". Viton(R) has a high temperature range similar to ethylene propylene but has the advantage of being somewhat more resistant to "dry heat." Viton(R) has a rather wide range of chemical compatibility. It has a useful temperature range of 0°E ( - 18°C.) to 350°E (177°C.).

TEFLON***

Teflon and teflon with fillers are considered more of a plastic than a resilient-type material. They are virtually unattached by any fluid. Their temperature usage has ranged from discs for cryogenic valves to discs for steam valves. They are not easily fabricated and are known to have "cold flow" characteristics which may contribute to objectionable leakage particularly on gases.

* Viton(R) is a registered trademark of DuPontDow Elastomers

** Flourel is a registered trademark of 3M

*** Teflon is a registered trademark of DuPont

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