Select Guide Of Drain Pipe For Indoor Unit - Hitachi Utopia RPI-2.5HRG Service Manual

4.3

Select Guide of Drain Pipe for Indoor Unit

G Selecting Method of Drain Pipe Diameter
<Step 1> Calculation of Drain Flow Volume
Calculate from that the drain flow volume is approximately 3 [l/hr] per 1HP of the indoor unit nominal
capacity.
For Example:
Common drain pipe for four 2HP indoor units and four 2.5HP indoor units.
(1) Total Horse Power of Indoor Unit: 42HP+42.5HP=18HP
(2) Total Drain Flow Volume: 18HP3 [l/hr.HP] =54 [l/hr]
<Step 2> Select Drain Pipe from Table A and B
(1) Horizontal Common Pipe with Slope 1/50:
(2) Horizontal Common Pipe with Slope 1/100: VP30 for above Example
(3) Vertical Common Pipe:
Table A. Permissible Drain Flow Volume of Horizontal Vinyl Pipe
JIS Symbol
VP20
VP25
VP30
VP40
VP50
Table B. Permissible Drain Flow Volume of Vertical Vinyl Pipe
JIS Symbol
VP20
VP25
VP30
VP40
VP50
VP65
VP75
G Drain Piping
Permissible Flow Volume [l/hr]
Inner Diameter
[mm] Slope=1/50
20
25
31
40
51
Inner Diameter
[mm]
20
25
31
40
51
67
77
Incorrect: Upward Slope
Unit
Rising Part
1/25 to 1/100 Down-Slope
Common Drain Piping
This drain pipe shall be
separating from other pipes.
VP30 for above Example
VP30 for above Example
Slope=1/100
39 27
70 50
125 88
247 175
473 334
Permissible Flow Volume
[l/hr]
220
410
730
1,440
2,760
5,710
8,280
Incorrect
Drain Piping
Connection
Correct
FIELD WORK INSTRUCTION
NOTE
Not Applicable to
Common Pipe
Applicable to
Common Pipe
NOTE
Not Applicable to
Common Pipe
Applicable to
Common Pipe
4-3