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Installation
Refrigerants
Applicable to all common non-flammable
refrigerants, including R717, H
S and non-
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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.
Attention!
SVA are shut off valves and must always be either
fully closed or fully open. Half open positions are
not allowed. In case the valve is installed close
to compressor (economizer lines, oil lines etc.)
or on other lines subjected to high vibrations
and pulsations, it is necessary to install special
lock washers on the valve. Please refer to the
catalogue for additional information.
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
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
© Danfoss A/S (RC-MDP/MWA), 2014-11
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 debris etc.
get into the valve during the welding procedure.
Be careful not to damage the teflon cone ring.
The valve housing must be free from 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).
vTightening
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
guarded against corrosion with a suitable
protective coating after installation and
assembly.
Protection of the ID ring when repainting the
valve is recommended.
SVA-SS valves are not painted and do not require
any protective coating.
Maintenance
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
v
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.
DKRCI.PI.KD0.A4.52 / 520H0745
Dismantling the valve (fig. 9)
Do not remove the bonnet while the valve is still
under pressure.
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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