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Installation
Refrigerants
Applicable to HCFC, HFC, R717 (Ammonia),
R744 (CO
), Propane, Butane, Iso-Butane
2
and Ethane.
The valve is only recommended for use
in closed circuits. For further information
please contact Danfoss.
Temperature range
–60/+150°C (–76/+302°F)
Pressure range
52 bar (754 psi)
The valve must be installed with the
spindle on top vertically upwards or in
horizontal position (fig. 1). SCA-X SS valves
should be opened by hand without the
use of tools or other devices. 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.
Flow direction
Direct the flow towards the cone as
indicated by an arrow on the valve housing
(fig. 1).
Welding
To prevent damage to the sealing parts in
the packing gland and between the valve
body and bonnet, as well as the teflon
gasket in the valve seat, the bonnet should
be removed before welding and protect it
from dirt and moisture (fig. 2).
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.
Be careful not to damage the teflon cone
ring.
The valve housing must be free from
stresses (external loads) after installation.
Stop check 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.
© Danfoss | DCS (MWA) | 2015.05
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
repositioned in the valve body (SCA-X SS
DN 15-40) (fig. 3).
Important for the SCA-X SS valves:
Full capacity is only obtained when the
spindle is screwed outward, "into bonnet",
i.e. counterclockwise (fig. 3).
Tightening
Tighten the bonnet with a torque wrench,
to the values indicated in the table (fig. 3).
Please note that the table (fig. 3) containing
maximum torque must be adhered to and
never exceeded.
Colours and identification
The SCA-X SS and CHV-X SS valves are
painted with a red primer in the factory.
Precise identification of the valve is made
via the green coloured 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 protected against
corrosion with a suitable protective coating
after installation and assembly.
Protection of the name plate when
repainting the valve is recommended.
Maintenance
Packing gland (only SCA-X SS types)
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. 4)
To backseat the valve, turn the spindle
counterclockwise until the valve is fully
open.
Pressure equalization (fig. 5)
In some cases, pressure forms behind the
packing gland. Hence, a handwheel or a
large washer (pos. A) should be fastened
on top of the spindle while the pressure is
equalized. The pressure can be equalized
by slowly screwing out the gland.
DKRCI.PI.FL1.R3.ML / 520H8210
Removal of packing gland (fig. 6)
Packing gland can now be removed.
Dismantling the valve (fig. 8)
Do not remove the bonnet while the valve
is still under pressure.
- Check that the gasket (pos. B) 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)
DN 15-40:
O-ring (pos. C) prevents the cone from
falling out. Pull the cone clear of the
bonnet. Ensure that the spring is not lost
in the process. Remove dirt, if any. Mount
O-ring (pos. C) on cone. Mount spring and
cone in bonnet.
Assembly
Remove dirt, if any, from pipes and housing
before assembly. Important for the
SCA-X SS valves: Full capacity is
only obtained when the spindle is
screwed outward, "into the bonnet", i.e.
counterclockwise (fig. 3).
Note:
For SCA-X SS and CHV-X SS sizes
DN 15-40 it is important to ensure that
the lower and upper part of the insert
is tightly screwed together (fig. 10) and
that this screw connection is kept tight
during repositioning of the cone in the
housing.
Use a torque wrench to tighten the bonnet
(fig. 3).
Tightening
Tighten the bonnet with a torque wrench,
to the values indicated in the table (fig. 3).
Tighten the packing gland with a torque
wrench, to the values indicated in the table
(fig. 7).
Use only original Danfoss parts, (including
packing glands and gaskets) for
replacement. Materials of new parts are
certified for the relevant refrigerant.
In cases of doubt, please contact your local
Danfoss sales office.
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