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Figure 7 - Pump head - thermal jacket
Can be used in conjunction with end cover relief
valve.
End Cover – Thermal Jacket
Figure 8 - End cover - thermal jacket
Application limits are:
•
Jacket Pressure: 2 bar (30 psi).
•
Temperature: 130ºC (265ºF).
3.11 SEALS AND FLUSHING
Three basic types of mechanical face shaft seal
are available on the HP & LH pumps.
The correct type should have been selected when
the pump was originally selected but you must
establish that the seal fitted is suitable for the
application before starting the pump.
Provide flushing system as required.
There is also 1 seal which is not a mechanical
face type; this is the Packed Gland seal available
on HP42/44 and HP52/54 size pumps.
The Single Mechanical Seal is suitable for
many clean fluids which do not require a more
sophisticated seal type. (Figure 9)
Figure 9 - Single mechanical seal (Size 4-8)
Note that silicon carbide-on-silicon carbide, seals
are
not
recommended
applications as the seal faces can bind together
– see chapter 5 CLEANING AND STERILISATION.
Pumps fitted with single seals require no special
installation.
However, pumps must never run dry, as this will
cause excessive heating of the seal faces.
Use flushed seals in pumps that need to run dry.
The Flushed Mechanical Seals fitted to HP &
LH pumps are run with a low-pressure liquid flush
between the primary mechanical seal and a lip
seal to form a barrier between the pump and the
atmosphere.
This allows the pump to be used for applications
where the single seal is unsuitable. (Figure 10)
Figure 10 - Flushed single seal (Size 4-8)
Flushed seals are used when:
for
steam-purged
14
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