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English
ADDITIONAL CHARGE
SPECIAL PRECAUTIONS WHEN CHARGING UNIT WITH SCROLL COMPRESSORS
These precautions are intended for use with Scroll compressors only with R22 and R410A refrigerants but are not applied to
others competitive Scroll compressors.
Scroll compressors have a very high volumetric efficiency and quickly pump a deep vacuum if there is insufficient refrigerant
in the system or if refrigerant is added too slowly. Operation with low suction pressure will quickly lead to very high discharge
temperatures. While this process is happening, the scrolls are not being well lubricated – scrolls depend on the oil mist in the
refrigerant for lubrication. A lack of lubrication leads to high friction between the scroll flanks and tips and generates additional
heat. The combination of heat of compression and heat from increased friction is concentrated in a small localized discharge
area where temperatures can quickly rise to more than 300
˚
C. These extreme temperatures damage the Scroll spirals and the
orbiting Scroll bearing. This damage can occur in less than one minute especially on larger compressors. Failure may occur
in the first few hours or the damage done during field charging may show up some time later.
Other typical field charging problems include undercharging, overcharging, moisture or air in the system etc. In time each
one of these problems can cause compressor failure.
Minimal equipment is required for field charging. The minimum equipment required to do a satisfactory job is:-
Set of service gauges
1.
Vacuum gauge
4.
Hoses
2.
Scales
5.
Vacuum pump
3.
Thermometer
6.
Cooling only
Indoor (FCRN)
50E
60E
71E
100E
125E
Outdoor (RN/RR)
50C
60C
71C
90D (1 PH)
90D (3 PH) 100D (1 PH) 100D (3 PH) 125D
Additional charge [g/m]
22
10
24
27
27
24
24
24
Heat Pump Units
Indoor (FCQN)
50E
60E
71E
100E
125E
Outdoor (RYN/RQ)
50C
60C
71C
90D (1 PH)
90D (3 PH) 100D (1 PH) 100D (3 PH) 125D
Additional charge [g/m]
16
16
41
42
42
37
37
39
Example:
FCRN 50E & RN 50C with 13m piping length, additional piping length is 5.5m. Thus,
Additional charge = 5.5[m] x 22[g/m]
=
121[g]
The refrigerant is pre-charge in the outdoor unit. If the piping length is less than 7.5m, then additional charge after vacuuming
is not necessary. If the piping length is more than 7.5m then use the additional charge value as indicated in the table.
Additional refrigerant charge [g] per additional 1m length as tabulated (for R410A models)
1 IM-5CKE-0912(0)DAIKIN-EN.indd 19
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10/4/12 5:54:32 PM
