TP40-240/2 Shaft Seals Manual

23
Materials of
secondary seals
Shaft seals
FXM
FXM (fluorinated copolymer) is particularly suitable for
extremely high temperatures and pressures as well as
for use in acid liquids and gasses within oil and gas
extraction (in boreholes, on land and at sea). Its resist-
ance to chemicals and high temperatures has been
considerably improved as compared to fluorized rub-
ber, with excellent resistance to hot water and steam.
• Elastic seal material
• Temperature range: –10°C to +275°C; for short peri-
ods up to +300°C
• Excellent hot water and steam resistance
• Available in material resistant to sudden decom-
pression.
Consisting of a modified structure of tetrafluoroethylene
(TFE) and propylene copolymers, FXM is widely used
within
• the chemical and petrochemical industry
• the aviation and space industry
• mechanical engineering
• refineries.
List of pumped liquids
The table below shows the resistance of the secondary
seal rubber materials to low and high temperatures and
to a selection of pumped liquids.
Based on water.
Legend
A number of typical pumped liquids are listed below.
The table below shows the resistance of the secondary
seal rubber materials to low and high temperatures and
to a selection of pumped liquids.
Factors NBR EPDM FKM FFKM FXM
Low temperatures
(temp. < 0°C)
++
–––
High temperatures
(temp. > +90°C)
–+
–
++
Acids ±±±+±
Alkalis + +
–
++
Glycols + + + +
Oils and fuels ±
–
++±
Solvents
––
±+
–
Symbol Meaning
+ Suitable
± Suitable under certain conditions
- Not suitable
Pumped liquid
Chemical
formula
Description
Acids
(pH < 7)
Sulphuric acid H
2
SO
4
Inorganic acid
Hydrochloric acid HCl Inorganic acid
Phosphoric acid H
3
PO
4
Inorganic acid
Nitric acid HNO
3
Inorganic acid
Chromic acid CrO
3
Inorganic acid
Acetic acid CH
3
COOH Organic acid
Formic acid HCOOH Organic acid
Alkalis
(pH > 7)
Sodium hydroxide NaOH
Potassium hydroxide KOH
Calcium hydroxide CaOH
Ammonium hydroxide NH
4
OH
Coolants
Propylene glycol CH
2
OHCHOHCH
3
Ethylene glycol C
2
H
4
(OH)
2
Glycerine CH
2
OHCH
2
OH
Fuels and
oils
Petrol Mineral oil
Diesel oil Mineral oil
Olive oil Vegetable oil
Solvents
Xylene C
6
H
4
(CH
3
)
2
Trichloroethylene C
2
HCl
3
Benzene C
6
H
6