Appendix C | Materials; Liquid Contact Materials - Gilson PLC 2050 User Manual

Liquid Contact Materials

the information provided in the following table is accurate to the best of our knowledge and
belief, but it is intended for general information only (classified by alphabetical order).
materiaL
ETFE
FEP
Fused Silica, SiO Glass
2
Graphite Fiber-Reinforced
Polytetrafluoroethylene
(GFP)
appendix C
MATeRiALS
Appendix C |
Liquid Contact Materials
DeSCriPtion
Ethylene tetrafluoroethylene is the generic name for the material such as Tefzel®.
A fluoropolymer used for sealing surfaces, it is resistant to most chemical attack;
however, some chlorinated chemicals will cause a physical swelling of ETFE tubing.
Fluorinated ethylene propylene is another member of the fluorocarbon family with
similar chemical properties. It is generally more rigid than PTFE, with somewhat
increased tensile strength. It is typically more transparent than PTFE, slightly less
porous, and less permeable to oxygen. FEP is not as subject to compressive creep at
room temperature as PTFE, and because of its slightly higher coefficient of friction is
easier to retain in a compression fitting.
High purity sand deposits provide the raw material for bulk refractory grade, which is
electric arc melted at extremely high temperatures. Optical and general purpose fused
silica rods and tubing are drawn from a melt made from high purity chemicals. Fiber
optic purity is made by thermal decomposition of high purity gaseous silica containing
chemicals. The glass may be clear or translucent, in which case it is often referred to
as fused quartz. The glass has very high viscosity, and this property allows the glass
to be formed, cooled and annealed without crystallizing. Fused silica glass is a very
low thermal expansion material, and so is extremely thermal shock resistant. The
material is also chemically inert up to moderate temperatures except to hydrofluoric
acid, which dissolves silica. It will devitrify above about 1100°C in the presence of
contaminants such as sodium, phosphorus and vanadium, with the formation of
cristobalite crystals which destroy the properties of the glass. The dielectric properties
are stable up through gigahertz frequencies.
GFP is a reinforced graphite fiber PTFE material used in moderate to extreme service
conditions. This material has excellent wear resistance in a wide range of speeds, in
medium pressures and in high temperatures. GFP performs well in water and other
liquid solutions and has limited use in vacuum or inert gas applications. Dynamic
surfaces in contact with a seal made from GFP should have a hardness of Rc 40 or
higher. GFP is recommended for applications that require good wear in liquids and
humid conditions at temperatures from -320°F to +500°F (-196°C to +260°C), such as
down-hole logging tools, adhesive, and epoxy dispensing equipment, and chemical
and laboratory equipment. GFP has excellent chemical compatibility. This material is
compatible with most fluids and gases, except some acids, such as sulfuric, nitric and
hydrofluoric acids.
PLC 2050/2250/2500 PurifiCation SyStemS
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