Table of Contents
Advertisement
•
Calculate the equivalent length of:
Vertical sections: length in metres of the straight
section pipe run plus the equivalent length of the
accessories installed (elbows, siphons, etc.).
Horizontal sections: length in metres of the actual
pipe run plus the equivalent length of the accessories
installed (elbows, etc.).
•
The total length is the sum of the equivalent lengths
of the vertical and horizontal sections.
•
For the vertical sections distinguish between ascending
vertical refrigerant flow sections and descending flow
sections.
•
Depending on the installation, the suction line (gas)
can be:
1.
The outdoor unit is above the indoor unit. Suction,
in cooling, with ascending refrigerant flow and
discharge, in heat pump mode, with descending
refrigerant flow.
.
The outdoor unit is below the indoor unit. Suction,
in cooling, with descending refrigerant flow and
discharge, in heat pump mode, with ascending
refrigerant flow.
3.
Units on the same level. The refrigerant flow
direction varies from one to the other direction,
depending on the operating cycle.
•
The liquid line is affected as explained later, depending
on the unit installation.
•
In the first installation type the gas line is calculated as
ascending suction line, and it is checked if the selected
diameter applies to the gas discharge line, if this is
descending.
In the second reverse installation type the discharge
line is calculated as ascending, and it is checked if the
diameter applies to the suction line, if this is descending.
•
The suction and discharge lines must comply with the
following points:
-
Maximum admissible pressure loss for the total
length = 0 kPa (3 psi).
-
Minimum velocity in ascending sections = 6 m/s.
-
Horizontal or descending sections: the velocity
can be between 4 and 6 m/s.
-
Maximum line velocity = 1 m/s.
-
The horizontal sections must have a % slope
towards the compressor.
-
In the vertical sections with ascending gas flow, it
is advisable to install siphons every 8 m in height.
Install the first siphon at the base of the column.
-
Select the suction and discharge line diameter
(Figs. 9 and 30).
Always calculate the diameter for the most unfavourable
line, that has the refrigerant gas flow in ascending direction.
Then you will see if the selected diameter for this line is
sufficient along its full length, when the unit changes the
operating cycle and the refrigerant flow is descending.
NOTE: See Table 1 for the standard outlet connection
diameters.
suction or discharge line diameter selection (Figs. 29 and 30)
Fig. 29 - Suction line diameter
Pressure loss/10 m equivalent length in m
Fig. 30 - Discharge line diameter
Pressure loss/10 m equivalent length in m
Legend
1
- 38UQZ 016 + 40ALZ 016
2
- 38UQZ 020 + 40ALZ 020
3
- 38UQZ 024 + 40ALZ 024
Selection process:
•
Enter the diagram in Fig. 9 or Fig. 30 horizontally at
the model number given in the legend.
•
The model number lines run horizontally and intersect
the various diameter curves (lines going from right to
left) and the various gas velocity curves (lines going
from left to right).
3
2
1
3
2
1
Advertisement
Table of Contents
