Panasonic U-72MF1U9 Technical Data Manual page 34

2. System Design
(3) Increasing the size of the refrigerant tubing
Increasing the tubing size of the gas tubes can reduce the loss of capacity caused by longer tubing lengths.
Refer to Table 2-11 to increase the tubing size. However, the maximum allowable tubing length must not be exceeded.
* The amount of additional refrigerant charge is determined from the liquid tube size only.
Table 2-10 Correction coeffi cient for equivalent length when the size of the gas tube (LM) is increased
Standard tube diameter
(gas tube, in.(mm))
Tube diameter after change
(gas tube, in.(mm))
Equivalent length correction
coefficient
* When increasing the size of the suction and discharge tubing (LM), multiply by the correction coeffi cient from Table 2-11 and
calculate the equivalent length for section LM.
Tubing equivalent length after size increase
= Standard tubing equivalent length × Equivalent length correction coeffi cient
1
2-2. Example of Tubing Size Selection for Extension and Additional Charge Amount
Sample calculation for the system below
2
Type 96
Lb
3
Elevation difference
H=16.4 ft.
4
Elevation difference
H=16.4 ft.
5
6
7
8
ø1/2" ø5/8" ø3/4"
(ø12.7) (ø15.88) (ø19.05)
ø5/8" ø3/4" ø7/8"
(ø15.88) (ø19.05) (ø22.22)
0.4
Type 96
LM
La
LA LB LC
L1
Type 36
LH
LG
L7
Type 48
ø7/8" ø1-1/8"
(ø22.22) (ø28.58)
ø1-1/8" ø1-3/8"
(ø28.58) (ø34.92)
0.5 0.6
LD LE 1 LE2
L2 L3
Type 18 Type 09
L8 L9
Type 18 Type 18
2 - 20
Design of 3WAY VRF SYSTEM
Extension indoor units
LF
L4 L5 L6
Type 36 Type 36 Type 18
Solenoid Valve Kit