Resin Types & Compatibility Notes

Fluoropolymer Resins

Three types are used in our hose assemblies:

PTFE (sometimes referred to as TFE) (Polyetrafluoroethylene)

FEP (Copolymer of tetrafluoroethylene and hexafluoropropylene)

PFA (Copolymer of tetrafluoroethylene and perfluoroalkyl

The various fluoropolymer materials are ideal as a hose material because of the following characteristics:
  • Insolubility an inertness to chemical attack
  • Purity
  • High thermal stability and upper service temperature
  • High melting points
  • Low coefficient of friction
  • Low water absorptivity
  • Low dielectric constant and dissipation factor
  • Excellent weatherability
  • Flame resistance

Purity
PTFE, PFA and FEP resins are approved by the Food and Drug Administration and the pharmaceutical industry (Pharmacopoeia VI). See approval section below for specific details.

Chemical Resistance
The following list of materials are the only materials that need consideration when conveyed through a hose. There are only 13 materials named. Only three are absolutely not to he used with PTFE, PFA, FEP. The other 10 are to he considered questionable with either high temperature and simultaneous impact resistance or temperature and pressure in combination.

  • Elemental Sodium
  • Elemental Potassium
  • Elemental Lithium
  • Fluorine (Fluorine is absorbed into the resin)
  • Chlorine Tri-fluoride (can be sensitive to impact ignition)
  • 80% Sodium Hydroxide
  • 80% Potassium Hydroxide
  • Borane (Only at 400° F to 500° F)
  • Aluminum Chloride
  • Ammonia
  • Amines
  • Imine (R-NH)
  • 70% Nitric Acid - slow oxidative attack only under pressure at 480 °F

Approvals
FDA/USDA Approvals
PTFE, PFA and FEP resins comply with the following FDA and USDA requirements:

Articles Intended for Food Contact
Reference: 21CRF177.1550 Perfluorocarbon resins covers PTFE, FEP and PFA resins and may be safely used as articles or components of articles intended to contact food in compliance with this regulation.

USDA Acceptance
The Department of Agriculture (USDA) has accepted PTFE, FEP and PFA fluoropolymer resins that comply with 21CFR177.1550 as components of materials in direct contact with meat or poultry food products prepared under Federal inspection.

US Pharmacopoeia Class VI
Samples of PTFE, FEP and PFA have been tested in accordance with USP protocol, and all meet the requirements for Class VI plastics. ISP testing was done to support the use of these fluoropolymer in pharmaceutical processing and food processing applications. While USP Class VI certification is not required for pharmaceutical processing, many pharmaceutical customers seeking ISO-9000 certification have requested it.

Colourants in Polymers
Reference: 21CFR178.3297 Colorants for Polymers.
This regulation permits certain colorants for use in polymers intended for food contact use. Included are TiO 2 , iron oxides, all-gas channel black, (carbon black) and ultra marine colorants.