TP32-80/2 Shaft Seals Manual

Shaft seals
24
Types of shaft seals
Types of shaft seals
The following pages give a short description of some of
Grundfos’ mechanical shaft seal types, including their
application profiles.
Due to the wear on carbon seal faces, the description
of carbon shaft seal types includes a table indicating
service intervals.
Grundfos type A
Grundfos type A seal is defined as an O-ring seal with
fixed seal driver.
Description/features
• Strong seal drivers ensure torque transmission even
under extreme operating conditions.
• Risk of fretting (wear corrosion) in corrosive liquids.
Fretting occurs when an O-ring wears the protective
oxide film of a stainless steel shaft.
• Risk of deposits around the O-ring as well as sei-
zure of the O-ring in liquids with a large content of
lime or sludge. Often observed as leakage in con-
nection with changes in operating conditions.
As standard available in tungsten carbide/tungsten car-
bide with EPDM or FKM O-rings.
Some sizes are available in silicon carbide/silicon car-
bide (SiC/SiC).
Fig. 30
Type A seal
Application profile
The type A seal has a tungsten carbide/tungsten car-
bide application profile.
Type A with tungsten carbide/tungsten carbide seal
faces
There is no relation between the indication of suitability
and the pressure-temperature diagram, but together
they form the application profile.
Suitability
Pressure-temperature diagram
The pressure-temperature diagram is based on clean
water.
The figures in the following table refer to the pressure-
temperature diagram.
Note: Noise occurs especially at low speeds.
Fig. 31 Pressure-temperature diagrams
TM00 2581 4593
Suitable
Suitable under
certain
conditions
Not
suitable
Alkaline liquids
Acid liquids
Dry running
Solid particles in liquid
Precipitating/lime-
containing liquids
Anti-freeze liquids
Pos. Range
1 Optimum duty range
2
Risk of periodical noise in connection with start-up and
variations in pressure and temperature
3 Risk of periodical noise
4 Reduced life
TM00 2588 4593