36
Sizing
Fig. 37 - Suction line
Pressure drop/10 m eqivalent length
Fig. 38 - Discharge line
Pressure drop/10 m eqivalent length
Legend:
1
Size 024
2
Size 036
2
Size 042
3
Size 048
4
Size 060
5
Size 072
6
Size 084
From Figure 38, for the selected unit we can obtain the pres-
sure drop corresponding to 10 m of equivalent length for each
diameter.
For other equivalent lengths, the pressure drop is obtained in
direct proportion. The total pressure drop for the line (sum
corresponding to the vertical and horizontal pipe runs) must not
be higher than 20 kPa.
Liquid line:
The liquid line diameter can be selected using table 6.
Table 6 - Liquid line
Size
Total equivalent length
Up to 10 m
From 10-30 m
From 30-50 m
024
3/8"
3/8"
3/8"
036
3/8"
3/8"
1/2"
042
3/8"
3/8"
1/2"
048
3/8"
1/2"
1/2"
060
3/8"
5/8"
5/8"
072
5/8"
5/8"
5/8"
084
5/8"
5/8"
3/4"
Necessary checks/precautions before start-up
-
Ensure that all electrical connections are properly
tightened.
-
Ensure that the unit is level and well-supported.
-
Check the condition of the ductwork in case damage has
occurred during installation.
-
The air filter should be clean and in place.
-
All the panels should be fitted and firmly secured with the
corresponding screws.
-
Make sure that there is sufficient space for servicing and
maintenance purposes.
-
Check the drain connections.
-
Ensure that there are no refrigerant leaks.
-
Confirm that the electrical power source agrees with the
unit nameplate rating.
-
Make sure that compressors float freely on the mounting
springs.
WARNING: The compressors are mounted on vibration
isolators. Do not loosen or remove the support mounting bolts.
Refrigerant charge
Gas tightness testing and dehydration
50TZ/YZ units are shipped fully charged with refrigerant R-407C
ready for operation. If, when the unit is run, symptoms of loss
of charge (for example, low pressure switch tripping or
abnormally low cooling capacities) are detected, first conduct a
leak test followed, if necessary, by a gas tightness test using
compressed nitrogen. For the latter all refrigerant must be
removed from the circuit. Transfer the refrigerant to a storage
tank and then rinse the circuit. For your information, we are
listing here some precautions that need to be taken into
consideration, when working with these units.
Refrigerant guidelines for R-407C
Refrigerant R-407C consists of a non-azeotropic blend of 23%
of R-32, 25% of R-125 and 52% of R-134a, and is character-
ised by the fact that at the time of the change in state the
temperature of the liquid/vapour mixture is not constant. All
checks must be pressure tests, and the appropriate pressure/
temperature ratio table must be used for the interpretation of
the values.
Leak detection is especially important for units charged with
refigerant R-407C. Depending on whether the leak occurs in
the liquid or the vapour phase, the proportion of the different
components in the mixture remaining in the unit is not the
same.
SPEED (m/s)