Leser 411 Instructions De Service page 25

• For liquids the blow-off pipe should point
downwards so that the medium can
completely drain out of the blow-off
chamber.
• The outlet flange of safety valves or blow-off
pipes must be directed so that no danger is
caused by the medium blowing off. The
following options are available:
- Blowing off into a container
- Safety valve and blowing-off pipes without
direct access
- Design with silencer.
12.10 Unfavourable environmental conditions
All LESER safety valves which may corrode are
coated with a protective coating during
manufacture which protects the safety valve
during storage and transport. In corrosive
environments a further corrosion protection is
required (refer to section 12.13). For extreme
conditions, LESER recommends stainless steel
safety valves. The supplementary loading
system must not be given a protective coating!
External media (e.g., rain water or dirt/dust)
must not enter the blowing-off pipe or come in
contact with functional components (e.g.,
guides with open bonnets) have to be avoided.
By analogy, the statements made in section 7
apply.
Simple preventive measures are possible:
• Protection of the blow-off chamber from
extraneous media and dirt
• Protection of the parts important to
operating from external media and dirt.
12.11 Leaks caused by foreign bodies
Foreign bodies must not remain in the
installation (e.g., welding beads, sealing
material such as hemp tape, PTFE tape,
screws, etc.). One option for avoiding foreign
bodies in the system is to flush it before
commissioning.
If leaks are caused by contamination between
the sealing surfaces, the safety valve can be
vented to clean the surfaces. If this does not
stop the leak, one of the sealing surfaces is
probably damaged. In this case the safety valve
has to be serviced.
12.12 Protection during storage and transport
All protective devices for transport and handling
have to be removed before installing the safety
valve.
After installation, the protection for the lever
must be removed from the bonnet as otherwise
the safety valve cannot be vented. The lever
must move freely, i.e. it must be in its initial
position and the coupling at the spindle must
not be connected to the lever.
In the case of lever safety valves, the wooden
wedge, which protects the sealing surfaces
from damage during transport, has to be
removed.
12.13 Corrosion protection
Moving parts and parts important to the
operating of the valve must not be impaired in
their motion, e.g. the blowing-off chamber. The
spindle guide must not be varnished.
The supplementary loading system must not be
coated with protective paint (refer also to
section 15).
12.14 Maintenance
Safety valves may only be serviced by skilled
staff.
Maintenance intervals cannot be specified by
LESER as they depend on many factors:
• Corrosive, aggressive and abrasive media
lead to rapid wear and require shorter main-
tenance intervals
• Frequent operating requires shorter main-
tenance intervals
• Maintenance intervals have to be agreed
between the operator, the inspector and the
manufacturer. Inspections must be carried
out at the time of the regular external and
internal checks of the pressure equipment.
12.15 Identification of safety valves
Before assembling
documentation must be checked in order to
ensure that the correct valve has been selected
for the assembly.
12.16 Lever safety valves
The set pressure of lever safety valves is
defined by the mass and the position of the
loading weights. It is not allowed to change
them.
No additional loading weights must be added.
The lever must not be used for suspending any
parts, e.g. for hanging clothes on.
13 Setting instructions for spring loaded safety
valves
The following operating instructions only apply
to valves without additional equipment. If there
is additional equipment (such as O-ring
dampers, proximity switches, bellows, ...)
please refer to the corrosponding assembly
instructions.
13.1 Lifting device H3
1. Remove shaft (40.4).
2. Pull lever (40.6) out to the side.
3. Loosen hexagonal head screw (40.3).
4. Unscrew and remove lever cover (40.1).
safety valves the
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