Fisher FSPI-180AE1 Service Manual page 27

According to the above table to calculate the total water flowrate for the confluence pipe selection.
For horizontal drainage pipe (The following table is for reference)
Reference value of inner
PVC pipe
diameter of pipe (mm)
PVC25
PVC32
PVC40
PVC50
PVC63
Attention: Adopt PVC40 or bigger pipe to be the main pipe.
For Vertical drainage pipe (The following table is for reference)
Reference value of inner
PVC pipe
diameter of pipe (mm)
PVC25
PVC32
PVC40
PVC50
PVC63
PVC75
PVC90
Attention: Adopt PVC40 or bigger pipe to be the main pipe.
Installation
Allowable maximum water flowrate (l/h)
Slope 1/50
20 39
25 70
31 125
40 247
51 473
Allowable maximum water flowrate (l/h)
20
25
31
40
51
67
77
Slope 1/100
27
50
88
175
334
220
410
730
1440
2760
5710
8280
Drainage pipe installation
Remark
For branch pipe
Could be used for confluence pipe
Remark
For branch pipe
Could be used for confluence pipe
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