© Danfoss A/S (AC-SMC/MWA), 11-2011
DKRCI.PI.KG0.A3.02 / 520H0746
3
Installation
Refrigerants
Applicable to all common non-flammable
refrigerants, including R717, H
2
S and non-
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-DL: –60/+150°C (–76/+302°F)
SVA-DH: –60/+150°C (–76/+302°F)
Pressure range
SVA-DL, SVA-DH:
40 bar (580 psi) at -60°C to +60°C
(-76°F to +140°F)
36 bar (522 psi) at +60°C to +80°C (+140°F
to +176°F)
32 bar (464 psi) at +80°C to +120°C (+176°F
to +248°F)
28 bar (406 psi) at +120°C to +150°C
(+248°F to +302°F)
The valves are designed for a max. working
pressure of 40 bar g (580 psi g).
Installation (fig. 1)
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 (fig. 2)
To achieve optimum flow conditions, the
valve should be installed with the flow
as indicated by the arrow (fig. 2) for SVA-
DH. Flow in the opposite direction is also
acceptable, but slightly reduces the k
v
- / C
v
value.
For SVA-DL, flow direction can only be from
the side in order for the pressure relief to
function.
Welding (fig. 4)
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,
compatible 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 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
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
systems 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 (fig. 5a)
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
replaced in the valve body (fig. 5a).
Tightening (fig. 5b)
Tighten the bonnet with a torque wrench,
to the values indicated in the table (fig. 5b).
Tightening of the bonnet should be
performed according to sound mechanical
practice.
Colours and identification
The SVA valves are painted with a red oxide
primer in the factory. 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.
Maintenance
Packing gland
When performing service and
maintenance, 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 equalized.
The pressure can be equalized by slowly
screwing out the gland.
Removal of packing gland
Handwheel and packing gland can now be
removed.
Dismantling the valve
Do not remove the bonnet while the valve
is still under pressure.
- Check that the top gasket has not been
damaged.
- Check that the spindle is free of scratches
and impact marks.
- If the teflon cone ring has been
damaged, the cone assembly must be
disassembled and the teflon renewed.
Replacement of the teflon seat (fig. 9a)
The Teflon seat can be renewed as shown
in fig. 9a. The bolts, pos. C, are unscrewed
and the tension ring can be removed. If
the Teflon seat is moderately damaged, it
can be turned around to use the fresh side
(check).
If the Teflon ring is deformed or has very
deep marks (> 1mm) it must be replaced
for strength. When remounting the bolts
on the tension ring, please refer to the
torque table.
Replacement of pressure relief seat on
SVA-DL (fig. 9b)
If the the SVA-DL has a leak over the
pressure relief seat, this can be changed:
- Remove the retaining ring (Seeger
circlip ring), pos. D, by using suitable
tool.
- Pull the seat assembly off the spindle
- Remove bolts, pos. A
- Remove tension ring, pos. B.
Again the Teflon ring can be turned around
if damages are moderate (moderate
deforming or pressure marks < 0.8 mm).
Otherwise the Teflon ring must be
replaced.
- Put tension ring and bolts back in place
and tighten bolts (pos. A) to the torque
indicated.
- Check that the wear rings, pos. E, are
intact and oil the rings before slowly and
lightly placing the seat assembly on the
spindle again.
- Refit the retaining ring, pos. D, in the
spindle groove and check that the cone
assembly refits on the spindle.
Replace U-sleeve seals or balls in SVA-
DH (fig. 9c)
If the two U-sleeve seals are damaged or
access is needed for the balls in the valve
spindle - valve seat bearing:
- Rotate the spindle clockwise all the way
down as for fully closed.
- Unscrew all the bolts in pos. B.
- Carefully remove the seat with the
welded on cylinder.
Now there is access to the two U-sleeve
seals (pos. C), the wear ring (pos. D), and
the balls behind the set screw (pos. E).
ENGLISH
