Fitters notes |
Practical tips |
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This chapter is devided into two sections: |
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Installation requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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The installation process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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Fitters notes |
Practical tips - installation requirements |
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Contents |
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Installation requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
129 |
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Tubing must be kept clean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 |
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Particularly damaging impurities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 |
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Problems caused by moisture in the system . . . . . . . . . . . . . . . . . . . . . . . . . |
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Problems caused by atmospheric air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 |
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Problems caused by oil and refrigerant breakdown . . . . . . . . . . . . . . . . . . . . . |
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Problems caused by other impurities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 |
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Component and material requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 |
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Impurities and moisture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 |
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Copper tubing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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Refrigerant requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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Compressor oil requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
132 |
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Notes
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© Danfoss A/S (AC-DSL/MWA), 10 - 2006 |
Fitters notes |
Practical tips - installation requirements |
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Installation requirements 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.
Tubing must be kept clean |
A well-dimensioned, correctly installed and |
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correctly commissioned refrigerant system is |
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fundamental to a reliable refrigeration system |
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with a long operating life. |
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An absolute requirement on the refrigerant |
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system is that it shall remain completely free of |
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foreign bodies (impurities). |
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Installation work must therefore be performed |
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with a high degree of cleanliness. This applies |
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especially to systems containing the new |
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refrigerants. |
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Particularly damaging impurities
Moisture
Atmospheric air
Soldering flux
Rust, copper oxide, scale
Metal swarf
Unstable oils
Certain fluorinated solutions (e.g. R11 or carbon tetrachloride)
Dirt or dust of any description.
Ac0_0037
Problems caused by moisture in the system
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_0027
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Practical tips - installation requirements |
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Problems caused by |
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Aeration |
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atmospheric air |
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Chemical reaction between refrigerant |
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and oil |
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Increased condensing pressure. |
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Problems caused by oil and refrigerant breakdown
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
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Problems caused by other impurities
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.
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Component and |
Compressors for refrigeration and heat pump |
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material requirements |
systems are put through a comprehensive clea- |
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Components |
ning process by the manufacturer so that, prac- |
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tically speaking, all traces of moisture and other |
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impurities are removed. |
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All other components in the system should be of |
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the same standard. |
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All components must fulfil cleanliness require- |
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ments. In cases of doubt, components should be |
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checked. |
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