A
PPLICATION
GUIDELINES
FRCC.PC.007.B5.02
43
I
NSTALLATION
Pressurize the system on HP side fi rst then LP side
to prevent rotation of the scroll. Never let the
pressure on BP side exceed the pressure on HP
side with more than 5 bar.
On SH180-240-300-380 models which have an
internal non return valve in discharge fi tting or
if an external non return valve is present on the
discharge line, we advise to pressurize the sys-
tem not quicker than 4.8 bar/s to allow pressure
equalization between LP and HP side over scroll
elements.
Leak detection must be carried out using a mix-
ture of nitrogen and refrigerant or nitrogen and
helium, as indicated in the table below. Never use
other gasses such as oxygen, dry air or acetylene
as these may form an infl ammable mixture.
Pressurize the system on HP side fi rst then LP
side.
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 mois-
ture also increase the risk of acid formation, giv-
ing 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;
SH 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 SH.
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 μm Hg
•
(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.
Leak detection
Vacuum evacuation and
moisture removal
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 mois-
ture level of 50 ppm end point dryness (EPD).
For new installations with SH compressors with
polyolester oil, Danfoss recommends using the
Danfoss DML (100% molecular sieve) solid core
fi lter drier. Molecular sieve fi lter driers with loose
beads from third party suppliers shall be avoid-
ed. For servicing of existing installations where
acid formation is present the Danfoss DCL (solid
core) fi lter driers containing activated alumina are
recommended.
The drier is to be oversized rather than under
sized. When selecting a drier, always take into ac-
count its capacity (water content capacity), the
system refrigeration capacity and the system re-
frigerant charge.
After burn out, remove & replace the liquid line
fi lter 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.
Leak detection with refrigerant
Leak detection with a mass spectrometer
Nitrogen & R410A
Nitrogen & Helium
Note 1:
Leak detection with refrigerant may be forbidden in some countries. Check local regulations.
Note 2:
The use of leak detecting additives is not recommended as they may aff ect the lubricant properties.