Danfoss VZH052 Manual page 43

Assembly line procedure
Piping assembly
System pressure test and
leak detection
Good practices for piping assembly is a pre-requisite to ensure compressor service life (system
cleanliness, brazing procedure...)
System cleanliness
Circuit contamination possible cause
Brazing and welding oxides
Filings and particles from the removal of burrs in
pipe-work
Moisture and air
Brazing procedure:
• Brazing operations must be performed by
qualified personnel.
• Make sure that no electrical wiring is connected
to the compressor.
• To prevent compressor shell and electrical box
overheating, use a heat shield and/or a heat-
absorbent compound.
• Clean up connections with degreasing agent
• Flow nitrogen through the compressor.
• Use flux in paste or flux coated brazing rod.
Before eventual un-brazing of the
compressor or any system component, the
refrigerant charge must be removed.
The compressor has been strength tested
and leak proof tested (<3g/year) at the factory.
For system tests:
• Always use an inert gas such as Nitrogen or
Helium.
Maximum compressor test pressures
Maximum compressor test pressure high side (HP)
Maximum compressor test pressure low side (LP)
* If an external non return valve is present on the discharge line, maximum pressurizing speed must be respected to ensure pressure
equalization between LP and HP side over scroll elements.
Requirement
During brazing, flow nitrogen through the system
Remove any particles and burrs generated by tube
cutting and hole drilling
Use only clean and dehydrated refrigeration grade
copper tubing
Opened compressor must not be exposed to air more
than 20 minutes to avoid moisture captured by PVE oil.
• Use brazing rod with a minimum of 5% silver
content.
• It is recommended to use double-tipped torch
using acetylene to ensure a uniform heating of
connection.
• To enhance the resistance to rust, a varnish on
the connection is recommended.
heat shield
• Pressurize the system on HP side first then LP
side.
• Do not exceed the following pressures:
41.1 bar (g) / 596 psig
HP-LP<36bar / 522 psi
33.3 bar (g) / 483 psig
LP-HP<5bar / 73 psi
Maximum speed 4,8 bar/ second (70 psi/s)*
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