Integrative notes to the operating manual for magnetic coupling centrifugal pumps conforming to the ATEX 94/9/CE directive TCK... - TBK... – TBAK…
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authorized and skilled personnel. Only original spare parts shall be used. For any replacement, refer to the Instructions
for Disassembly and Assembly of the Single-stage Centrifugal Pumps.
RESIDUAL RISK: In the event of running in conditions of insufficient lubrication, due to internal
frictions, some surfaces of the pump may become hot and reach temperatures much higher
than the Tx temperature for which the pump has been classified. The rotating mechanical parts
may be subject to seizing.
7.5 – OPERATION WITH HOT LIQUIDS
The pump does not have any insulation for the internal heat. The material being used for manufacturing is an excellent
thermal conductor. The classification of the pump for the Tx temperature class has been carried out on the basis of the
indications received from the end-user on the specific conditions about the type of applications for which the pump is
foreseen. For testing in the factory of POMPETRAVAINI, clean water at ambient temperature has been used. The tests
carried out on the pumps have indicated that - even with foreseeable malfunctioning (for further indications ask
POMPETRAVAINI) in the standard test conditions the surface temperature of the pump does not exceed the T4
classification (135°C).
During operation in the different applications, the external surface of the pump body reaches quickly a temperature
which is equal to the liquid pumped. Therefore, it is possible to bring the pump to an external surface temperature much
higher than the one reached under standard test conditions when fed with hot liquids. The Tx indication for the
temperature class is derived from this.
The user must evaluate - according to his own analysis of the Zone where the pump is used - if the indicated
temperature class is admissible.
If the pump shall be used with liquids either at a temperature higher than 100°C or in ambient with
atmospheric temperature over 45°C, it is suitable to monitor the operation temperature of the journal to
avoid reaching or exceeding a value of 85°C.
A positive temperature increase on some components of the mechanical seal must be added to the temperature
reached by the pump body. For this purpose, read carefully the contents of Chapter 6 of this booklet regarding the
mechanical sealing system.
RESIDUAL RISK: When the pump is used for pumping liquids at high temperatures, its surface
temperature practically is equal to the liquid pumped. The compatibility between the
temperature of the liquid pumped, the mechanical features of the pump and the surrounding
ambient conditions must be verified.
7.6 – OPERATION IN PRESENCE OF CAVITATIONS
The pump must
NEVER
run in conditions where cavitation
is
present or may be originated. The phenomenon of
cavitation is a direct consequence of the type and of the temperature of the liquid pumped, the pressure in the
pump’s
suction
pipe
and of other minor factors. For the installation of the pump, follow the in
structions as
shown in
Chapter 9 under paragraph 9.2 of the Operator’s Manual.
If the operating conditions compel the pump to run in conditions close to the event of this phenomenon, it is advisable to
check frequently the operating conditions, in order to act before a longer exposure to cavitations can damage the pump.
Checking must be carried out by authorized and skilled personnel. During checking there must be no heavy vibrations
on the pump or the typical noise (rattle) which indicates the presence of cavitations.
The phenomenon can be noticed only when the pump is running and in special operating conditions. The steps of how
to reduce or eliminate them are suggested in Chapter 16 of the Operator’s Manual.
RESIDUAL RISK: The operation with cavitations on the pump will cause a quick wear of the
impeller and heavy vibrations on the whole pump, which may bring about sudden and
unforeseeable mechanical trouble on all components of the pump.
7.7 – OPERATION AT WRONG ROTATION SPEED
The pump must
NEVER
run at a rotation speed higher than the one foreseen in the design. The correct rotation speed
in relation to the operating conditions and the kind of application of the pump is shown on the pump’s
name
-plate
(Fig.
1)
and on the Confirmation of order.
The effective rotation speed in rpm. of the pump – when it is running – may differ by a maximum of 5% more or less
from the value shown on the
nam
e-plate and on the Confirmation of order. If any greater difference of the rotation speed
is noticed, check the installation, the electric connections and the operating conditions in order to make sure that
they correspond to the design features.