FEP (Fluorinated Ethylene Propylene): Properties & Applications

What is FEP?

FEP (fluorinated ethylene propylene) is a fully fluorinated, melt-processable fluoropolymer in the same family as PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy), and PVDF (polyvinylidene fluoride). Because every backbone carbon is shielded by fluorine, FEP carries the broad chemical inertness and non-stick, low-friction surface associated with PTFE — but, like PFA, it melts and flows at processing temperature, so it can be conventionally extruded, molded, and heat-sealed rather than paste-extruded and sintered the way PTFE must be. That melt-processability is also why FEP is optically clear.

The trade-off against PTFE and PFA is temperature: FEP is rated to a 400°F continuous service temperature, where PTFE and PFA reach 500°F. FEP is sometimes specified by the trade names Teflon™ FEP (Chemours) and Neoflon™ FEP (Daikin); the chemistry is the same FEP whatever the brand.

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FEP Properties

FEP’s properties make it the clear, melt-processable option among fluoropolymer tubing grades: chemically inert, non-flammable, an excellent electrical insulator, and optically transparent, with near-zero moisture absorption. The table below lists the measured physical properties of Altaflo 200 FEP (the standard grade), with the environmental-grade Altaflo 2E0 alongside.

Physical Property	ASTM Test	Altaflo 200 FEP (standard)	Altaflo 2E0 FEP (enviro)
Upper service temperature	—	400°F	400°F
Service temperature range	—	-100°F to 400°F	-100°F to 400°F
Specific gravity	D 792	2.15	2.12–2.17
Tensile strength	D 1708	4,000 psi	3,500 psi
Elongation	D 638	400%	300–400%
Flexural modulus	D 790	90,000 psi	12,000 psi
MIT flex life	D 2176	200,000	5,000
Hardness	D 2240	Shore D 57–60	Shore D 57–60
General	—	Meets/exceeds ASTM D 2116 Type IV	Meets ASTM D 2116

Values are based on tests performed at 73°F and can vary with temperature, chemical concentration, and pressure. Altaflo 200 is a 100% virgin-grade FEP tubing; the Altaflo 2E0 ENVIRO grade is a cost-effective product for environmental sampling and other less aggressive service

FEP melts at approximately 500°F (260°C) — standard FEP resin value, not on the Altaflo sheet, well above its 400°F continuous service ceiling — the gap is what makes FEP melt-processable and weldable, and gives it the optical clarity PTFE lacks.

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What Is the Temperature Range of FEP?

FEP (Altaflo 200) carries a continuous service temperature range of -100°F to 400°F. The 400°F upper limit is the practical dividing line in the fluoropolymer family: below it, FEP delivers full fluoropolymer chemical resistance at lower cost than PFA; above it, PTFE and PFA — both rated to 500°F — are the correct choice. FEP retains useful flexibility and impact resistance down to its -100°F lower limit, which is part of why it appears in low-temperature fluid handling and analytical work.

Service temperature is not the same as melting point: FEP melts near 500°F (260°C) but is rated for continuous use only to 400°F, because mechanical strength falls off well before the material melts.

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How Does FEP’s Chemical Resistance Compare?

FEP is fully fluorinated, so its chemical resistance is in the same class as PTFE and PFA: it is chemically inert to most industrial acids, bases, oxidizers, and solvents, and will not impart taste or odor. This is a meaningful step up from the partially fluorinated PVDF, which has limited compatibility with strong bases and some polar solvents.

Where FEP differs from PTFE and PFA is not chemistry but temperature and form: all three resist nearly the same chemicals, but FEP does so only up to 400°F, while PTFE and PFA hold to 500°F. For aggressive chemical service within FEP’s temperature range, FEP gives essentially the same inertness as PTFE and PFA at lower cost — and adds optical clarity for sight-glass and flow-monitoring use. For a specific chemical, check an FEP chemical compatibility chart and confirm the service temperature; where temperatures exceed 400°F, step up to PTFE or PFA.

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FEP vs. PTFE and PFA: Where It Fits

FEP is the right fit when an application needs full fluoropolymer chemical resistance plus optical clarity or melt-processability, and the operating temperature stays below about 400°F. It bridges PTFE and PFA: like PFA it is melt-processable and transparent, but it is rated lower and costs less; like PTFE it is chemically inert and low-friction, but unlike PTFE it can be conventionally extruded, molded, and heat-sealed, and it is clear. The table compares upper service temperature and tensile strength across Pexco’s Altaflo fluoropolymer grades.

Material	Grade	Upper Service Temp	Upper Service Temp
PTFE (polytetrafluoroethylene)	Altaflo 100	500°F (550°F short-term)	2,500–3,000 psi
FEP (fluorinated ethylene propylene)	Altaflo 200	400°F	4,000 psi
PFA (perfluoroalkoxy)	Altaflo 400	500°F	4,500 psi
PVDF (polyvinylidene fluoride)	Altaflo 500	250°F	5,000–7,000 psi
ETFE (ethylene tetrafluoroethylene)	Altaflo 700	300°F	3,100–6,800 psi

Within the Altaflo line, FEP is the cost-effective choice for melt-processable, transparent fluoropolymer service below 400°F. Choose PFA over FEP when service runs hotter (to 500°F) or demands the lowest extractables for semiconductor wet process; choose PTFE when you need the 500°F ceiling, the lowest friction, or filled/machined stock; FEP wins on clarity, conventional processability, and cost. For direct, material-by-material breakdowns, see the FEP vs. PTFE comparison guide and Pexco’s FEP vs. PFA comparison for extreme environments.

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FEP Grades and Forms

Pexco supplies FEP in two product grades and multiple converted forms, so the same chemistry can be matched to a clear chemical line, a high-purity run, or an environmental sampling loop.

Altaflo 200 FEP (standard). Produced from 100% virgin-grade FEP resin, Altaflo 200 is the workhorse grade: chemically inert, non-flammable, with superior electrical insulation, low permeability, and near-zero moisture absorption. Its excellent clarity makes it ideal for sight-glass and flow-monitoring applications, and its outstanding UV transmission makes it a clear choice for UV water-purification systems. Altaflo 200 will not impart taste or odor, is FDA compliant for food contact under 21 CFR 177.1550, meets USP Class VI, and is certified to NSF 61 and NSF 372 for drinking-water system components. It is offered in smooth-bore, convoluted, and coiled-hose constructions and may be used with flare or conventional fittings, in sizes from 1/32″ to 2-1/8″ OD as standard, with custom extrusions available up to 4″ OD.

Altaflo 2E0 FEP ENVIRO (environmental grade). A cost-effective FEP designed specifically for environmental sampling — applications that need the purity of FEP without exposure to aggressive chemicals or harsh conditions. It shares FEP’s 400°F ceiling and excellent UV transmission and near-zero moisture absorption, at lower tensile strength and flex life than the standard grade.

Beyond tubing, Pexco converts FEP into FEP rod for machined components, alongside the full fluoropolymer tubing line. Note that Pexco does not supply FEP heat-shrink tubing — its heat-shrink line is polyolefin, PVC, and PVDF; FEP heat shrink offered elsewhere is a different product. FEP is also sold under the trade names Teflon™ FEP (Chemours) and Neoflon™ FEP (Daikin); these describe the same FEP chemistry Pexco extrudes.

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FEP Applications

FEP is specified where chemical resistance has to coexist with clarity, cleanliness, or conventional processability at moderate temperatures. Its core applications cluster in five areas:

• Chemical process and fluid handling — chemically inert tubing, pipe, and hose for acids, oxidizers, and solvents below 400°F, where FEP delivers PTFE-class resistance at lower cost. See fluid handling.
• Sight glass, flow monitoring, and UV systems — FEP’s optical clarity and outstanding UV transmission make it the fluoropolymer of choice for visual flow monitoring and UV water-purification systems, applications the opaque grades cannot serve.
• High-purity fluid handling — clean, chemically inert fluid paths where clarity and lower cost matter. For ultra-high-purity semiconductor wet process, PFA and UHP PFA remain Pexco’s default; FEP fits less critical high-purity lines. See semiconductor.
• Medical and life sciences — laboratory, analytical, and chromatography lines where USP Class VI compliance, clarity, and chemical inertness matter. See medical & life sciences.
• Electrical insulation — high-temperature wire and cable insulation drawing on FEP’s superior dielectric properties and non-flammability. See electrical & electronics.

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How Pexco Manufactures FEP

Pexco’s value in FEP is processing, not resin production: as a North American fluoropolymer manufacturer, the company converts 100% virgin-grade FEP resin into finished tubing, pipe, and rod to engineered tolerances. Because Pexco runs the extrusion and converting in-house, an FEP requirement can be matched to the right grade (standard Altaflo 200 vs. environmental Altaflo 2E0), wall, and dimension — in smooth-bore, convoluted, or coiled-hose form, and in custom sizes up to 4″ OD — rather than forced onto a stock size. This processing-and-converting capability, applied across the full Altaflo fluoropolymer line, is what lets Pexco route a single chemical-service, high-purity, or fluid-handling requirement to the correct material and form.

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Frequently Asked Questions