Hitachi UTOPIA RAS-4HVRP2E - Three Principles on Refrigerant Piping Work; Suspension of Refrigerant Piping

3 Piping work and refrigerant charge
General notes before performing pipe work
SMGB0136 rev.0 - 07/2021
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3.1.2 Three principles on refrigerant piping work
In order to avoid oxidation, pay much careful attention to basic piping work control to avoid inltration of moisture or dust
during the refrigerant piping work.
Three principles Cause of failure Presumable failure Preventive action
1. Dry
Keep good dryness
• Water inltration due to
insufcient protection at pipe
ends
• Dewing inside of pipes
• Insufcient vacuum pumping
time
Icing inside tube at expansion
valve
(Water choking)
+
Generation of hydration and
oxidation of oil
↓
Clogged strainer, etc., insulation
failure and compressor failure
Pipe protection
1 Pinching
2 Taping
↓
Flushing
↓
Vacuum Drying
One gram of water turns into gas
(approx. 1000 lrs) at 1 Torn
Therefore, it takes long time to
vacuum-pump by a small vacuum
pump
2. Clean
No dust inside of
pipes
• Inltration of dust or other
through the pipe ends.
• Oxidation lm during brazing
without blowing nitrogen.
• Insufcient ushing by
nitrogen after brazing
Clogging of expansion valve,
capillary tube and lter
→Oxidation of oil
→Compressor failure
↓
Insufcient cooling or heating
compressor failure
Pipe Protection
1 Mounting Caps
2 Taping
3 Pinching
↓
Flushing
3. No leakage
No leakage shall
exist
• Brazing failure
• Failed aring work and
insufcient torque of
squeezing are
• Insufcient torque of
squeezing anges
Refrigerant shortage
→Performance decrease
→Oxidation of oil
→Overheating of compressor
↓
Insufcient cooling or heating
compressor failure
Careful Basic Brazing Work
↓
Basic Flaring Work
↓
Basic Flange Connecting Work
↓
Air Tight Test
↓
Holding of Vacuum
3.1.3 Suspension of refrigerant piping
Suspend the refrigerant piping at certain points and prevent the refrigerant piping from touching weak parts of the
building such as walls, ceiling, etc. (If touched, abnormal noises may occur due to the vibration of the piping. Pay special
attention in case of short piping length).
A. Fire-proof section treatment.
B. Indoor unit.
In order to x the piping to wall or ceilings use suspension and clamping systems as shown in the following gure.