Daikin RDT-135c Installation And Maintenance Manual page 44

Mechanical Installation: RFS/RCS Permanent Split Systems
Table 18: Pressure-vacuum equivalents
Absolute pressure above zero
Microns
0
50
100
150
200
300
500
1,000
2000
4,000
6000
8,000
10,000
15,000
20,000
30,000
50,000
100,000
200,000
500,000
760,000
Charging the System
RCS units are leak tested at the factory and shipped with a
nitrogen holding charge. If the holding charge has been lost
due to shipping damage, then contact the factory for
authorization and advice for repairing the leak and evacuating
the system.
After all refrigerant piping is complete and the system is
1
evacuated, it can be charged as described in the paragraphs
following. Connect the refrigerant drum to the gauge port
on the liquid shutoff valve and purge the charging line
between the refrigerant cylinder and the valve. Then open
the valve to the midposition.
2 If the system is under a vacuum, stand the refrigerant drum
with the connection up, open the drum, and break the
vacuum with refrigerant gas.
With a system gas pressure higher than the equivalent of a
3
freezing temperature, invert the charging cylinder and
elevate the drum above the condenser. With the drum in
this position and the valves open, liquid refrigerant flows
into the condenser. Approximately 75% of the total
requirement estimated for the unit can be charged in this
manner.
4 Refrigerant charging with Zeotropes—R-407C is a
zeotropic mixture (see "Refrigerant Leaks" on page 117).
42
Vacuum below 1 atmosphere
PSIA Mercury (mm)
0 760.00
0.001 759.95
0.002 759.90
0.003 759.85
0.004 759.80
0.006 759.70
0.009 759.50
0.019 759.00
0.039 758.00
0.078 756.00
0.117 754.00
0.156 752.00
0.193 750.00
0.290 745.00
0.387 740.00
0.580 730.00
0.967 710.00
1.930 660.00
3.870 560.00
9.670 260.00
14.697 0
Approximate
fraction of
Mercury (in.)
1 atmosphere
29.921
29,920
29.920
29.920
29.910
29.910
29.900
29.880
29.840
29.760
29.690
29.600
29.530
29.330
29.130
28.740
27.950
25.980
22.050
10.240
0 1 Atmosphere
During initial charging or "topping" off a system, it is
important to remove the refrigerant from the charging
cylinder in the liquid phase. Many of the cylinders for the
newer refrigerants use a dip tube so that in the upright
position liquid is drawn from the cylinder. DO NOT vapor
charge out of a cylinder unless the entire cylinder is to be
charged into the system. Refer to charging instructions
provided by the refrigerant manufacturer.
After 75% of the required charge enters the condenser,
5
reconnect the refrigerant drum and charging line to the
suction side of the system. Again, purge the connecting
line, stand the drum with the connection side up, and place
the service valve in the open position.
Note: Stamp the total operating charge per circuit on the unit
nameplate for future reference.
Adding refrigerant to the suction must always be done by
trained service personnel that are experienced with the risks
associated with liquid-related damage to the compressor.
Take special care to add refrigerant slowly enough to the
suction to prevent damage when first adding charge to the
suction. Adjust the charging tank hand valve extremely slow
Boiling point
of H2O at each
pressure (
— —
1/15,200 –50
1/7,600 –40
1/5,100 –33
1/3,800 –28
1/2,500 –21
1/1,520 –12
1/760 1
1/380 15
1/189 29
1/127 39
1/95 46
1/76 52
1/50 63
1/38 72
1/25 84
1/15 101
2/15 125
1/4 152
2/3 192
212
CAUTION
o
F)
IM 738-2