EBARA 3SF Manual De Instrucciones página 6

ZONE 2
Area in which an explosive atmosphere made up of a mixture
of gases or vapours would form with difficulty.
Should such a mixture appear in this area, however, it
would last for a short period only.
In plants, the person in charge must define the areas in which
explosive atmospheres can form, or select apparatuses
EN
that are suitable for the areas and check the installation,
maintenance and operation conditions;
Ex - symbol which refers to pumps designed and produced
in accordance with European norm standards;
c к b - these letters specify the type of protection;
In particular
c - production safety;
к - protection by immersion into liquid (the ignition sources
are emerged into a protective liquid in order to render
them inefficient or remove them from the explosive
atmosphere);
b - protection by ignition source control;
IIC - substance group;
T2 to T4 resp. Pump temperatures classification (the
maximum temperature of the internal and external surface
of the pump must be lower than the ignition temperature of
the atmosphere in which the gases, vapours or clouds are
present) suitable for the corresponding gas temperature
classification. The user must therefore process fluids at a
temperature that is in conformity with this classification,
keeping in mind the indications given in the relative manual
and by current legislations.
4.3 NOTES
- The pumps in category 2G are suitable for areas 1 and
2;
- Pumps with a given temperature class are also suitable
for all higher class substances (for example pumps with
a temperature classification of T4 are also suitable for
substances with T3, T2, T1 temperature classification)
but evidently within the operation limits specified in the
manual;
- Explosion-proof pumps should be used in areas where
the surrounding temperature is from -20÷40°C and the
atmospheric pressure is from 0.8 to 1.1 bar;
- Maximum viscosity of the fluid permitted: 30 mm
(opportunely sizing the motor);
- mm2/s (opportunely sizing the motor);
- The protection system indicated by the letters c k b is
indispensable in all cases where a category 2 product
is necessary. Although a category 3 pump is sufficient,
a device for controlling the fluid level is not necessary
(paragraph 6.2 – Precautions for avoiding dry running).
Protection by ignition source control can therefore not
be used ("b");
- Pumps marked for use in the presence of group C gases
can be used with group A or B gases. Gas and vapour
classification is in accordance with the MESG values
(maximum experimental safe gap) in conformity with EN
60079-0.
5. EARTH CONNECTIONS
Continuity of the metal parts is guaranteed, and FIG. 2
indicates where the pump shoud be earthed.
6
6. INSTALLATION
6.1 PRECAUTIONS FOR AVOIDING
MISALIGNMENT OF THE MOVING PARTS
To avoid misaligning the moving parts during installation
and during the life of the pump, follow the indications given
in the "INSTALLATION" paragraph of the instruction manual.
6.2 PRECAUTIONS FOR AVOIDING DRY RUNNING
AND BREAKAGE OF THE MECHANICAL SEAL
To prevent the mechanical seal from breaking, ensure that
it is always lubricated while it works.
A reduction of the level of the liquid inside the pump and
especially irregular operations such as dry running must
be avoided through the use of safety devices.
In order to respect the essential requisites dictated by
European Directive 2014/34/EU, these safety devices
must be certified and the protection method used against
explosions must be selected correctly.
FIGURES 3 and 4 illustrate how to assemble the level
control devices onto the relative switchboard, which blocks
the pump when there is no fluid (indications on how to
connect and set the switchboard are given in the specific
instruction manual).
In this case, the pump filling actions are modified as follows
(see instruction manual).
Even though these figures represent two different sensors
(a diapason and a conductive sensor), the filling operations
remain the same.
6.3 PUMP OPERATION WITH AN OBSTRUCTED/
CLOSED DELIVERY VALVE
FIGURE 5 shows the assembly drawing of the flow rate
measurer (Mp) which must be assembled at delivery
so that the pump (P) blocks when falls below 5% of the
maximum return point.
In this case the electric contact (C) deactivates/activates,
disconnecting the electric power supply and rendering
the pump safe.
This value guarantees respect of temperature classification
on the internal and external surfaces of the pump.
6.4 DAMAGE CAUSED BY CHEMICAL NON
COMPATIBILITY BETWEEN LIQUID AND
COMPONENTS
Check the chemical compatibility between the fluid and
the pump parts.
6.5 CAVITATION
/s It is important to always check correct pump sizing (therefore
2
it is essential to verify the value needed by the pump using
the NPSH curves. These curves can be found in the product
general catalogues).
6.6 HOT FLUIDS
TAB. 2 gives the maximum temperature that the fluid can
reach in each temperature classification (these values are
permitted respecting the conditions expressed in point
4.3 NOTES).
It is important to install a reading device in order to guarantee
the maximum temperature of the fluid.
Should the limit value indicated in TAB. 2 be exceeded, a
release apparatus should switch the pump off.
The temperature measuring instrument must be in conformity
with the EN 13463-1 norm (category 4 of the Machines
Directive) and carry an ATEX marking that is compatible
with that of the pump. The switchboard which guarantees
intervention when the limit values are exceeded must be
FAILURE SAFE.