Danfoss SVA-ST 15 Installation page 3

ENGLISH
Installation
Refrigerants
Applicable to all common non-flammable
refrigerants, including R717, H
corrosive gases/liquids dependent on
sealing material compatability. Flammable
hydrocarbons are not recommended. The
valve is only recommended for use in
closed circuits. For further information
please contact Danfoss.
Temperature range
SVA-ST: –50/+150°C (–58/+302°F)
SVA-LT: –60/+150°C (–76/+302°F)
SVA-SS: –60/+150°C (–76/+302°F)
Pressure range
The valves are designed for a max. working
pressure of 40 bar g (580 psi g), for both
standard (SVA-ST) and low temperature
versions (SVA-LT, SVA-SS).
Installation
The valve must be installed with the
spindle vertically upwards or in horizontal
position (fig. 1). Valves should be opened
by hand without the use of tools or other
devices (fig. 3). The valve is designed to
withstand a high internal pressure.
However, the piping system should be
designed to avoid liquid traps and reduce
the risk of hydraulic pressure caused by
thermal expansion. It must be ensured that
the valve is protected from pressure
transients like "liquid hammer" in the
system.
Recommended flow direction
To achieve optimum flow conditions, the
valve should be installed with the flow
towards the valve cone as indicated by the
arrow on the side of the valve body
(fig. 2). Flow in the opposite direction is
also acceptable (fig. 2), but slightly reduces
the k - / C value.
v v
Welding
The bonnet should be removed before
welding (fig. 4) to prevent damage to the
O-rings in the packing gland and between
the valve body and bonnet, as well as the
teflon gasket in the valve seat. Only
materials and welding methods, compa-
tible with the valve housing material, must
be welded to the valve housing. The valve
should be cleaned internally to remove
welding debris on completion of welding
and before the valve is reassembled.
Avoid welding debris and dirt in the
threads of the housing and the bonnet.
Removing the bonnet can be omitted
provided that:
The temperature in the area between the
valve body and bonnet during welding
does not exceed +150°C/+302°F. This
temperature depends on the welding
method as well as on any cooling of the
valve body during the welding itself.
(Cooling can be ensured by, for example,
wrapping a wet cloth around the valve
body.) Make sure that no dirt, welding
© Danfoss A/S (RC-CMS / MWA), 09-2005
debris etc. get into the valve during the
welding procedure.
Be careful not to damage the teflon cone
ring.
S and non- The valve housing must be free from
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stresses (external loads) after installation.
Stop valves must not be mounted in sy-
stems where the outlet side of the valve is
open to atmosphere. The outlet side of the
valve must always be connected to the
system or properly capped off, for example
with a welded-on end plate.
Assembly
Remove welding debris and any dirt from
pipes and valve body before assembly.
Check that the cone has been fully screwed
back towards the bonnet before it is re-
placed in the valve body (fig. 5a).
Tightening
Tighten the bonnet with a torque wrench,
to the values indicated in the table
(fig. 5b).
Colours and identification
The SVA valves are painted with a red oxide
primer in the factory. Stainless steel valves
are not painted. Precise identification of
the valve is made via the ID ring at the top
of the bonnet, as well as by the stamping
on the valve body. The external surface of
the valve housing must be prevented
against corrosion with a suitable protective
coating after installation and assembly.
Protection of the ID ring when repainting
the valve is recommended.
Packing gland
When performing service and mainte-
nance, replace the complete packing gland
only, which is available as a spare part. As a
general rule, the packing gland must not
be removed if there is internal pressure in
the valve. However, if the following
precautionary measures are taken, the
packing gland can be removed with the
valve still under pressure:
Backseating (fig. 6)
To backseat the valve, turn the spindle
counter-clockwise until the valve is fully
open.
Pressure equalization (fig. 7)
In some cases, pressure forms behind the
packing gland. Hence a handwheel or
similar should be fastened on top of the
spindle while the pressure is equal-ized.
The pressure can be equalized by slowly
screwing out the gland.
Removal of packing gland (fig. 8)
Handwheel and packing gland can now be
removed.
Dismantling the valve (fig. 9)
Do not remove the bonnet while the valve
is still under pressure.
RI7AE352 → DKRCI.PI.KD0.A1.52 / 520H0745
Maintenance
Check that the O-ring (pos. A) has not
been damaged.
Check that the spindle is free of
scratches and impact marks.
If the teflon cone ring has been
damaged, the whole cone assembly
must be replaced.
Replacement of the cone (fig. 9)
Unscrew the cone screw (pos. B) with an
Allen key.
SVA-ST/LT/SS 15-40 ........................ 2.0 mm A/F
SVA-ST/LT 50-65 .............................. 2.5 mm A/F
SVA-ST/LT 80-100 ................................4 mm A/F
SVA-ST/LT 125-150 ............................5 mm A/F
SVA-ST/LT 200 ......................................6 mm A/F
(An Allen key is included in the Danfoss
Industrial Refrigeration gasket set).
Remove the balls (pos. C).
Number of balls in pos. C:
SVA-ST/LT/SS 10-20 ..................................10 pcs.
SVA-ST/LT/SS 25-65 ..................................14 pcs.
SVA-ST/LT 80-200 .....................................13 pcs.
The cone can then be removed. Place the
new cone on the spindle and replace the
balls. Refit the cone screw in again using
Loctite No. 648. to ensure that the screw is
properly fastened.
Replacement of backseat seal (fig. 10)
For sizes DN 80-200 only:
The valve backseat is a special teflon ring. If
this is damaged, it must be replaced. Screw
the spindle out of the bonnet. Carefully
remove the original backseat seal and
mount a new one in the angled contact
surface directly inside the opening in the
bonnet. Avoid folding and damage to
the teflon ring, or damage to the contact
surface at the top of the valve during
assembly.
Assembly
Remove any dirt from the body before the
valve is assembled. Check that the cone
has been screwed back towards the bonnet
before it is replaced in the valve body
(fig. 5a).
Tightening
Tighten the bonnet with a torque wrench,
to the values indicated in the table (fig. 5b).
Tighten the packing gland with a torque
wrench, to the values indicated in the table
(fig. 11).
Use only original Danfoss parts, including
packing glands, O-rings and gaskets for
replacement. Materials of new parts are
certified for the relevant refrigerant.
In cases of doubt, please contact Danfoss.
Danfoss accepts no responsibility for
errors and omissions. Danfoss Industrial
Refrigeration reserves the right to make
changes to products and specifications
without prior notice.
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