Thesec ompounds ares uitablef or continuousu se at 4008 F/2058 C
depending upon the corrodent.
On the low temperature side, these rubbers are generally serviceable in
dynamic applications down to K 108 F/K 238 C. Flexibility at low temperatures is afunction of the material thickness. The thinner the cross section, the
less stiffthe material is at everytemperature. The brittle point at athickness
of 0.075 in. (1.9 mm) is in the neighborhood of K 508 F/K 458 C.
Being halogen-containingp olymers, these elastomers are more resistant
to burning than exclusivelyh ydrocarbon rubbers. Normally compounded
material willb urnw hen directly exposed to flame, but it will stop burning
when the flame is removed. However,i tm ust be rememberedt hat
undera na ctual fire condition, the fluoroelastomers willb urn. During
combustion, fluorinatedp roducts such as hydrochloric acid can be given
off. Special compounding can improve the flame resistance. One such
formulation has been developed fort he spacep rogram that willi gnite
underc onditions of the NASA test that specifies1 00% oxygena t6 .2 psi
absolute.
Fluoroelastomers have been approved by the U.S.F ooda nd Drug
Administration for use in repeated contactwith food products.
The fluoropolymers provide excellent resistance to oils, fuels, lubricants,
most minerala cids,m anya liphatic anda romatich ydrocarbons
(carbont etrachloride,b enzene, toluene, and xylene) that act as solventsf or
other rubbers, gasoline, naphtha, chlorinated solvents, and pesticides.
Special formulationsc an be produced to obtain resistance to hot mineral
acids.
These elastomers are not suitablefor use with low molecular weight esters
and ethers, certain amines, or hot anhydrous hydra-fluoric or chlorosulfonic
acids.Table 6.16 provides the compatibility of fluoroelastomerswith selected
corrodents. Reference [1]provides additional information.
The main applications of the fluoroelastomers are in those applications
requiringr esistance to high operatingt emperatures togetherw ith
high chemical resistance to aggressive media and to those characterized
by severe operating conditions that no other elastomer can withstand.
Linings and coatings are sucha pplications. Theirc hemical stability solves
the problem of chemical corrosion by making it possible to use them for such
purposesa s:
Aprotective liningfor power station stacks operated with highsulfur
fuels
Tank linings for the chemical industry
Thea dvantageso ft he fluoroelastomersa re in their high degree
of resistance to aggressive media. Their cost is less than the perfluoroelastomers but greater than other elastomeric materials used for the lining of
vessels.
Sheet Linings
339
CAT8247—CHAPTER 6—6/10/2006—12:29—SRIDHAR—XML MODEL B–pp. 287–402
depending upon the corrodent.
On the low temperature side, these rubbers are generally serviceable in
dynamic applications down to K 108 F/K 238 C. Flexibility at low temperatures is afunction of the material thickness. The thinner the cross section, the
less stiffthe material is at everytemperature. The brittle point at athickness
of 0.075 in. (1.9 mm) is in the neighborhood of K 508 F/K 458 C.
Being halogen-containingp olymers, these elastomers are more resistant
to burning than exclusivelyh ydrocarbon rubbers. Normally compounded
material willb urnw hen directly exposed to flame, but it will stop burning
when the flame is removed. However,i tm ust be rememberedt hat
undera na ctual fire condition, the fluoroelastomers willb urn. During
combustion, fluorinatedp roducts such as hydrochloric acid can be given
off. Special compounding can improve the flame resistance. One such
formulation has been developed fort he spacep rogram that willi gnite
underc onditions of the NASA test that specifies1 00% oxygena t6 .2 psi
absolute.
Fluoroelastomers have been approved by the U.S.F ooda nd Drug
Administration for use in repeated contactwith food products.
The fluoropolymers provide excellent resistance to oils, fuels, lubricants,
most minerala cids,m anya liphatic anda romatich ydrocarbons
(carbont etrachloride,b enzene, toluene, and xylene) that act as solventsf or
other rubbers, gasoline, naphtha, chlorinated solvents, and pesticides.
Special formulationsc an be produced to obtain resistance to hot mineral
acids.
These elastomers are not suitablefor use with low molecular weight esters
and ethers, certain amines, or hot anhydrous hydra-fluoric or chlorosulfonic
acids.Table 6.16 provides the compatibility of fluoroelastomerswith selected
corrodents. Reference [1]provides additional information.
The main applications of the fluoroelastomers are in those applications
requiringr esistance to high operatingt emperatures togetherw ith
high chemical resistance to aggressive media and to those characterized
by severe operating conditions that no other elastomer can withstand.
Linings and coatings are sucha pplications. Theirc hemical stability solves
the problem of chemical corrosion by making it possible to use them for such
purposesa s:
Aprotective liningfor power station stacks operated with highsulfur
fuels
Tank linings for the chemical industry
Thea dvantageso ft he fluoroelastomersa re in their high degree
of resistance to aggressive media. Their cost is less than the perfluoroelastomers but greater than other elastomeric materials used for the lining of
vessels.
Sheet Linings
339
CAT8247—CHAPTER 6—6/10/2006—12:29—SRIDHAR—XML MODEL B–pp. 287–402