Danfoss Praktiske tips Service guide

Fitters notes Practical tips

Page

This chapter is devided into two sections:

Installation requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

The installation process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

© Danfoss A/S (AC-DSL/MWA), 10 - 2006 DKRCC.PF.000.G1.02 / 520H1459 125

Practical tips

Fitters notes Practical tips - installation requirements

Contents Page

Installation requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

Tubing must be kept clean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

Particularly damaging impurities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

Problems caused by moisture in the system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

Problems caused by atmospheric air. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130

Problems caused by oil and refrigerant breakdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130

Problems caused by other impurities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130

Component and material requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130

Components. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130

Impurities and moisture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

Copper tubing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

Refrigerant requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

Compressor oil requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

© Danfoss A/S (AC-DSL/MWA), 10 - 2006 DKRCC.PF.000.G1.02 / 520H1459 127

Practical tips

Notes

128 DKRCC.PF.000.G1.02 / 520H1459 © Danfoss A/S (AC-DSL/MWA), 10 - 2006

Fitters notes Practical tips - installation requirements

Installation requirements

Tubing must be kept clean

More and more commercial refrigeration systems
and air conditioning plants of a similar size are
built up around hermetic and semihermetic
compressors. These compressors, as compared
to the open type, are normally more vulnerable
to impurities in the refrigerant system and to
incorrect operating conditions.

Therefore, in modern refrigeration systems, there
are special demands on the quality of installation
work and commissioning.

Ac0_0003

A well-dimensioned, correctly installed and
correctly commissioned refrigerant system is
fundamental to a reliable refrigeration system
with a long operating life.
An absolute requirement on the refrigerant
system is that it shall remain completely free of
foreign bodies (impurities).
Installation work must therefore be performed
with a high degree of cleanliness. This applies
especially to systems containing the new
refrigerants.

Particularly damaging
impurities

Problems caused by moisture in
the system

Moisture
Atmospheric air
Soldering ux
Rust, copper oxide, scale
Metal swarf
Unstable oils
Certain uorinated solutions (e.g. R11

or carbon tetrachloride)
Dirt or dust of any description.

Water separation and ice formation
(blockage) in the expansion valve

Acid formation
Ageing and breakdown of the oil
Corrosion
Copper precipitation (dissolved copper

from tubing deposited on bright steel
parts in the compressor)

Damage to the insulating lacquer on
motor windings.

Ac0_0010

Ac0_0037

Ac0_0027

Practical tips

© Danfoss A/S (AC-DSL/MWA), 10 - 2006 DKRCC.PF.000.G1.02 / 520H1459 129

Fitters notes Practical tips - installation requirements

Problems caused by
atmospheric air

Problems caused by oil
and refrigerant breakdown

Aeration
Chemical reaction between refrigerant

and oil
Increased condensing pressure.

Ac0_0038

Formation of organic and inorganic acids
Corrosion
Poor lubrication
Abnormal wear
Oil discolouration (darkening)
Sludge formation
Leaking discharge valves because of

oil carbon deposits
Increased discharge gas temperature
Compressor damage
Motor burnout

Ac0_0046

Problems caused by other
impurities

Component and
material requirements

Components

The other impurities mentioned can cause:

Accelerated chemical processes
(breakdown)

Mechanical or electrical faults

High temperature accelerates the breakdown
processes, therefore abnormally high condensing
temperatures and, especially, abnormally high
discharge pipe temperatures must be avoided.

For the reasons just mentioned, a number of
requirements must be met. Some of these are
described in the next chapter.

Ac0_0047

Compressors for refrigeration and heat pump
systems are put through a comprehensive clea­ning process by the manufacturer so that, prac­tically speaking, all traces of moisture and other
impurities are removed.

All other components in the system should be of
the same standard.

All components must full cleanliness require­ments. In cases of doubt, components should be
checked.

Ac0_0048

130 DKRCC.PF.000.G1.02 / 520H1459 © Danfoss A/S (AC-DSL/MWA), 10 - 2006