Installation
Moisture obstructs the proper functioning of the
compressor and the refrigeration system.
Air and moisture reduce service life and increase
condensing pressure, and cause excessively high
discharge temperatures, which can destroy the
lubricating properties of the oil. Air and moisture
also increase the risk of acid formation, giving
rise to copper platting. All these phenomena
can cause mechanical and electrical compressor
failure.
For these reasons it’s important to perform a
vacuum dehydration on the system to remove
all residual moisture from the pipe-work after
assembly; SM / SY / SZ compressors are delivered
with < 100 ppm moisture level. The required
moisture level in the circuit after vacuum
dehydration must be < 100 ppm for systems with
an SM / SY / SZ.
• Never use the compressor to evacuate the
system.
• Connect a vacuum pump to both the LP & HP
sides.
• Evacuate the system to a pressure of 500 μmHg
(0.67 mbar) absolute.
Do not use a megohm meter nor apply power to
the compressor while it’s under vacuum as this
may cause internal damage.
Vacuum evacuation and
moisture removal
The compressor has been strength tested and
leak proof tested (<3g/year) at the factory.
• Always use an inert gas such as Nitrogen or
Helium
• Pressurize the system on HP side then LP side
• Do not exceed the test pressures indicated in
the previous section “System pressure test”
Leak detection
Filter driers
A properly sized & type of drier is required.
Important selection criteria include the driers
water content capacity, the system refrigeration
capacity and the system refrigerant charge.
The drier must be able to reach and maintain
a moisture level of 50 ppm end point dryness
(EPD).
For new installations with SM/SY/SZ compressors
with polyolester oil, Danfoss recommends using
the Danfoss DML (100% molecular sieve) solid
core filter drier. Molecular sieve filter driers with
loose beads from third party suppliers shall be
avoided. For servicing of existing installations
where acid formation is present the Danfoss
DCL (solid core) filter driers containing activated
alumina are recommended.
The drier is to be oversized rather than under
sized. When selecting a drier, always take into
account its capacity (water content capacity),
the system refrigeration capacity and the system
refrigerant charge.
After burn out, remove & replace the liquid
line filter drier and install a Danfoss type DAS
burn-out drier of the appropriate capacity.
Refer to the DAS drier instructions and technical
information for correct use of the burnout drier
on the liquid line.Also for new installations with
SM compressors with mineral oil the Danfoss DCL
drier is recommended.
For the initial charge the compressor must not
run and eventual service valves must be closed.
Charge refrigerant as close as possible to the
nominal system charge before starting the
compressor. This initial charging operation must
be done in liquid phase. The best location is on
the liquid line between the condenser outlet
and the filter drier. Then during commissioning,
when needed, a complement of charge can be
done in liquid phase: slowly throttling liquid in
on the low pressure side as far away as possible
from the compressor suction connection while
compressor is running. The refrigerant charge
quantity must be suitable for both summer and
winter operations.
Vacuum or charge from one side can seal the
scrolls and result in a non-starting compressor.
When servicing, always ensure that LP/HP
pressures are balanced before starting the
compressor.
Be sure to follow all government regulations
regarding refrigerant reclamation and
storage. For more detailed information, see
“Recommended refrigerant system charging
practice” news bulletin FRCC.EN.050.
Refrigerant charging
45
AB237986441643en-010801
Application Guidelines
Содержание R134a
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