McQuay MDS030AR Applications Manual page 90

Design & installation Guide For McQuay MDS Multi System
-90-
4.3.11 Refrigerant charging
Calculate the refrigerant amount accord-
ing to the length of the liquid pipe
The refrigerant amount of fill of the outdoor unit before delivery (excluding the refrigerant to
be filled in the site pipe)
The additional amount of the refrigerant depends on the liquid pipe diameter and length (based
on the liquid pipe).
Diameter of the liquid pipe (mm)
Amount of the additional refrigerant (g/m)
Calculation of the additional amount of the refrigerant
Additional amount= (
+ ( 9.52 liquid lengthx80g/m) + (
4.3.12 Vacuum Pumping
Vacuum drying of the refrigerant pipe
Vacuum drying
Vacuum drying is to dry the pipe by vaporizing the water (liquid) in the pipe with a vacuum pump
and discharge it. Under one atmospheric pressure, the water boiling point (steam temperature)
is 100 degrees Celsius. When the pressure in the pipe is reduced to nearly vacuum by using
a vacuum pump, the boiling point reduces. When the boiling point goes under the outdoor
temperature, the water in the pipe vaporizes.
Before vacuum drying, make sure you know how to select a vacuum pump and how to
maintain.
6.35
50
15.88 liquid pipe length x180g/m) + (
6.35 liquid length x50g/m).
0
-60
-160
-260
-360
-460
-560
-700
-720
-730
-740
-755
Frozen point
-760
-20 -10 0 10 20
Add additional refrigerant
9.52 12.7
80 120
12.7 liquid length x120g/m)
Necessary vacuum
Outdoor temperature range
30 40 50 60 70
15.88 19.05
180 290
760
700
600
500
400
300
200
60
50
40
30
20
10
5
0mmHg