Leser 411 Instructions De Service page 27

14 Handling
There is a risk of injury from sharp edges and
burrs. For this reason all parts have to be handled
with caution.
There is a risk from safety valves falling over.
They always have to be secured adequately.
During dismantling the spring must not be
tensioned. Otherwise there is danger of injury
from flying parts. Observe the assembly
instructions for the relevant safety valves!
Before dismantling you should always check
whether there is, or could be, any medium in the
bonnet; also check what the medium is.
There is a great risk of injury, chemical burns
or poisoning if there is any remaining medium
inside the safety valve.
One should use conventional high quality tools in
order to minimise the risks arising from bad
quality tools or inadequate tools. Any necessary
special tools are indicated in the assembly
instructions.
Safety valves may only be dismantled and
assembled by skilled staff.
The training can be carried out:
• In the workshop by experienced staff
• At LESER training seminars
• By means of LESER documentation, e.g.,
videos, operating instructions, catalogues,
assembly instructions
The maintenance staff must be informed about
the risks during dismantling and installing the
safety valves.
Contamination and damage to the safety valve
must be avoided. Suitable cartons, protective
covers for the flanges, wrapping foil, shipping
palettes etc. have to be used. The packaging
must be completely removed before installation
as otherwise the function of the safety valve
cannot be guaranteed.
Safety valves have to be handled with care as
otherwise the vulnerable sealing surfaces can be
damaged or the safety valve might even be
rendered useless.
Safety valves must be stored in a dry place. The
optimum storage temperature is 5 °C to 40 °C.
For o-ring discs temperatures below freezing
should be avoided, if possible. The temperature
resistance, in particular of the o-ring materials,
has to be taken into account.
Upper limit for storage: 50 °C
Lower limit for storage: -10 °C
15 Supplementary loading system
Even if the external energy supply (compressed
air) fails, the direct-loaded safety valve is still fully
functional. In this case the function is equivalent
to the LESER standard safety valve without
supplementary loading system.
The compressed air filter must be serviced at
regular intervals as specified in the maintenance
instructions.
The installation should contain an air dryer. The
compressed air should have a dew-point of
minimum +2 °C.
The maximum pressure of the air supply is 10
bar, the minimum pressure is 3.5 bar. If the
pressure rises above or falls below the specified
interval, this may lead to temporary or permanent
failure of the supplementary loading system. As a
result the safety valve does not function or it
will work as a standard valve without the
supplementary loading system.
The supplementary loading system should be
serviced and checked at least once a year by
specially trained staff. For this essential work
LESER offers a maintenance service which may
be incorporated in a service agreement. Training
and experience with handling the supplementary
loading system in combination with the safety
valves are essential.
The supplementary loading system has to be
fitted in accordance with the rules and standards
and the specifications distributed by LESER. If
serviced correctly, failures due to contamination
of the pressure and control lines can be ex-
cluded.
The control unit is to be protected from
contamination. It has to be ensured that it is
always closed. For special applications LESER
offers an encapsulated box sealing the control
unit.
The actuator on the safety valve itself as well as
sliding parts inside an open bonnet must be
protected from contamination. Otherwise there is
the danger of jamming.
Temperatures:
The controls and actuators are designed for
applications between 2 °C and 60 °C.
• At temperatures above 60 °C the compressed
air connections must be as long as possible
and equipped with a water seal.
• The control unit and actuators have to be
positioned in a way that their temperature will
not exceed 60 °C.
• At a temperature below 2 °C there may be
danger of icing-up, therefore it may be
necessary to heat control unit, control lines and
tapping lines.
The supplementary loading system is
E
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