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Sticky medium
Use the valve with bellows and a heating
jacket, optionally incorporate security
plate into the system.
Freezing or solidifying medium
The body and the pipes should be kept in
a state incapable freezing or solidifying of
media - apply the heating.
"Seizing" of the sealing surfaces of the
seat and valve disc preventing their
separation at the set pressure
If the properties of the medium and the
operating conditions do not exclude such
possibility - appropriate frequency of
inspections and repairs of the safety valve
must be adapted, and the time of valve
check provided in the operating records of
protected device / system should be
strictly observed.
No repeatability of valve opening
pressure (conventional valves, i.e.
unbalanced)
Variable superimposed backpressure
Replace conventional safety valve with the
valve with bellows compensating
superimposed backpressure changes
Checking of safety valve is not
possible
Inlet pressure is lower than 75% of the
set pressure
check the safety valve with a proper
pressure – follow manufacturer's
instructions.
Damages within the lifting unit
Inspect the lifting unit and when
necessary replace damaged parts to new
ones.
Leak at sealing surface
Incorrect transport or storage - wrong
position during transport and storage,
protective cap from the inlet and outlet
of the valve have fallen out and thus
the impurities entered into the valve
During transport and storage follow
manufacturer's instructions. If the inner
part of the valve has been polluted, it
need to be cleaned before installing the
valve in the system in order to avoid
damage to the sealing surfaces.
There is no corresponding relationship
between the set pressure and the
working pressure.
Working pressure shall be:
For compressible fluids and set
pressure equal or higher than 2 bars -
maximum 80% of set pressure,
For compressible fluids and set
pressure below 2 bars – working
pressure should be lower by 0,4 bar
than set pressure,
For incompressible fluids and set
pressure equal or higher than 3 bars –
maximum 75% of set pressure,
For incompressible fluids and set
pressure below 3 bars – working
pressure should be lower than 0,75 bar
than set pressure.
Lever not in neutral position (in case of
closed valves and low pressures)
Move the lever to the neutral position
Vibrations of the safety valve
Diagnose the cause of these vibrations,
and if possible - remove the source. If the
vibrations cannot be prevented mount
appropriate damping systems.
If the chattering of the valve is due to
incorrect valve selection (see "Vibration")
- analyse the accuracy of the valve
selection and if necessary replace it.
Medium pollutions, foreign substances
between the disc and seat
Shortly lift valve disc to remove any
impurities, and if it does not bring the
expected results – take off the valve and
perform regeneration of the sealing
surfaces of the seat and the disc or
