Supplementary Loading System; Combined Safety Valve And Bursting Disc - Leser 411 Instructions De Service

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
E
regular intervals
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 excluded.
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
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
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as specified in the
above 60 °C the
necessary to heat control unit, control lines
and tapping lines.
The supplementary
connected to the safety valve via a coupling.
The coupling must not be blocked by objects. It
is neither necessary nor permitted to apply a
protective coating to the actuator.
The pressure tapping lines must not be shut off.
If there are shut-off devices they have to be
designed in such a way that they cannot be
closed, e.g., by means of locking bars or seals.
LESER control units are equipped with a shut-
off device for maintenance purposes. They are
secured against shutting-off by means of a
locking bar. This locking bar must not be
removed.
The pressure switches are wire-locked and
sealed. This seal indicates that the setting has
not been changed. It is not permitted to
manipulate the pressure switches (e.g., by
opening the seal and modifying the adjustment
or by opening the switching contacts, ...)!
If a test gag is used during pressure testing of
the installation it must be removed after the
test.
16 Combined Safety Valve and Bursting
Disc
The type test approval of the combination of
bursting discs of a certain manufacturer with
LESER safety valve ensures that both the
functional and performance requirements are
met. If you require information on the tested
combinations, please contact LESER.
Combinations of LESER safety valves and
bursting discs of other manufacturers are
permissible, if they
requirements. This shall be certified for each
individual case.
The following points should be noted in
particular:
•
Operating instructions for the bursting disc.
•
Safety valves must not lose their function
by placing the upstream bursting disc.
•
The space between the rear side of the
bursting disc and safety valve inlet should
be monitored.
•
The bursting disc should be designed in a
way that it cannot be installed incorrectly.
•
The bursting disc has to open free of
fragments. Bursting disc components must
not enter the inlet connecting pieces of the
safety valve thus impairing the function.
loading system is
meet the safety
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