BUTTERFLY VALVE SEAT SELECTION GUIDE
Below is a general butterfly valve seat selection guide. When selecting seats, always consult the pressure / temperature charts and corrosion resistant guide or contact the factory for engineering help.
EPDM -
EPDM is a terpolymer elastomer made from ethylene-propylene diene monomer. EPDM has good abrasion and tear resistance and offers excellent chemical resistance to a variety of acids and alkalines. It is susceptible to attacks by oils and is not recommended for applications involving petroleum oils, strong acids, or strong alkalines. EPDM should not be used on compressed air lines. It has exceptionally good weather aging and ozone resistance. Temperature rating is from -20ºF to +225ºF (250ºF intermittent service). It is fairly good in ketones and alcohols.
BUNA-N (HYCAR or Nitrile) -
Buna-N is a general purpose polymer which has good resistance to oil, water, solvents and
hydraulic fluids. It also displays good compression, abrasion resistance, and tensile strength. This material performs extremely well in process areas where paraffin base materials, fatty acids, oils, alcohols or glycerins are present, since it is totally unaffected. It should
not be used around high polar solvents (acetones, ketones) chlorinated hydrocarbons, ozone, or nitro hydrocarbons. Temperature
range is +225°F maximum. Hycar is black in color and should not be used where discoloration cannot be tolerated. It is regarded as a comparable replacement to neoprene.
VITON® (Fluorocarbon, FKM, or FPM) - Fluorocarbon elastomers are inherently compatible with a broad spectrum of
chemicals. Because of this extensive chemical compatibility which spans considerable concentration and temperature ranges,
fluorocarbon elastomers have gained wide acceptance as a material of construction for knife gate valve seats. Fluorocarbon can be
used in most applications involving mineral acids, salt solutions, chlorinated hydrocarbons and petroleum oils. It is particularly good
in hydrocarbon service. Temperature rating is from -20°F to +300°F.
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