Installation manual

Page 26 IM-487
Leak Testing
In the case of loss of the nitrogen holding charge, check
the unit for leaks prior to charging the complete system.
Leak testing must be done to current EPA standards and
regulations. After making any necessary repair, evacuate
the system as described in the following paragraphs.
Evacuation
After it has been determined that the unit is tight and there
are no refrigerant leaks, evacuate the system. Use a vac-
uum pump with a pumping capacity of approximately 3
cu.ft./min. and the ability to reduce the vacuum in the unit
to at least 1 millimeter (1000 microns).
1. Connect a mercury manometer or other type of micron
gauge to the unit at a point remote from the vacuum pump.
For readings below 1 millimeter, use an electronic or other
micron gauge.
2. The triple evacuation method is recommended and is par-
ticularly helpful if the vacuum pump is unable to obtain
the desired 1 millimeter of vacuum. The system is first
evacuated to approximately 29" (740 mm) of mercury.
Enough refrigerant vapor is then added to the system to
bring the pressure up to 0 pounds (0 microns).
3. Then the system is once again evacuated to 29" (740 mm)
of vacuum. This procedure is repeated three times. This
method can be most effective by holding system pressure
at 0 pounds (0 microns) for a minimum of 1 hour between
evacuations. The first pulldown will remove about 90% of
the noncondensables, the second about 90% of that
remaining from the first pulldown, after the third, only 1/
10 of 1% of noncondensables will remain.
Table 6 shows the relationship between pressure, microns,
atmospheres, and the boiling point of water.
To service liquid line components, the manual shutoff valve is
closed and refrigerant is pumped into the condenser.
Table 6: Pressure Vacuum Equivalents
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, charge the system with enough refrig-
erant to raise the unit pressure to 30 psig after first repairing
the leaks and evacuating the system.
1. After all refrigerant piping is complete and the system has
been evacuated, charge it as described in the following
paragraphs. 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.
3. With a system gas pressure higher than the equivalent of a
freezing temperature, invert the charging cylinder and ele-
vate the drum above the condenser. With the drum in this
position and the valves open, liquid refrigerant will flow
WARNING
Do not use oxygen to build up pressure.
Using oxygen to build up pressure can cause an explo-
sion, resulting in severe personal injury or death.
ABSOLUTE PRESSURE ABOVE ZERO VACUUM BELOW 1 ATMOSPHERE APPROXIMATE
FRACTION OF
1 ATMOSPHERE
BOILING POINT
OF H2O AT EACH
PRESSURE
o
F (°C)
MICRONS PSIA MERCURY
(MM)
MERCURY
(IN.)
0 0 760.00 29.921 — —
50 0.001 759.95 29,920 1/15,200 - 50 (-45)
100 0.002 759.90 29.920 1/7,600 - 40 (-40)
150 0.003 759.85 29.920 1/5,100 - 33 (-36)
200 0.004 759.80 29.910 1/3,800 - 28 (-33)
300 0.006 759.70 29.910 1/2,500 - 21 (-29)
500 0.009 759.50 29.900 1/1,520 - 12 (-24)
1,000 0.019 759.00 29.880 1/760 1 (-17)
2000 0.039 758.00 29.840 1/380 15 (-9)
4,000 0.078 756.00 29.760 1/189 29 (-2)
6000 0.117 754.00 29.690 1/127 39 (4)
8,000 0.156 752.00 29.600 1/95 46 (8)
10,000 0.193 750.00 29.530 1/76 52 (11)
15,000 0.290 745.00 29.330 1/50 63 (17)
20,000 0.387 740.00 29.130 1/38 72 (22)
30,000 0.580 730.00 28.740 1/25 84 (29)
50,000 0.967 710.00 27.950 1/15 101 (38)
100,000 1.930 660.00 25.980 2/15 125 (52)
200,000 3.870 560.00 22.050 1/4 152 (57)
500,000 9.670 260.00 10.240 2/3 192 (89)
760,000 14.697 0 0 1 Atmosphere 212 (100)