Drainage pipe installation   
224  Installation 
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) 
PVC pipe 
Reference value of inner 
diameter of pipe (mm) 
Allowable maximum water flowrate (l/h)
Remark 
Slope 1/50  Slope 1/100 
PVC25  20  39  27 
For branch pipe 
PVC32  25  70  50 
PVC40  31  125  88 
Could be used for confluence pipe PVC50  40  247  175 
PVC63  51  473  334 
Attention: Adopt PVC40 or bigger pipe to be the main pipe. 
For Vertical drainage pipe (The following table is for reference) 
PVC pipe 
Reference value of inner 
diameter of pipe (mm) 
Allowable maximum water flowrate (l/h)
Remark 
PVC25  20  220 
For branch pipe 
PVC32  25  410 
PVC40  31  730 
Could be used for confluence pipe 
PVC50  40  1440 
PVC63  51  2760 
PVC75  67  5710 
PVC90  77  8280 
Attention: Adopt PVC40 or bigger pipe to be the main pipe. 
6.2.3  Individual design of drainage pipe system 
  The drainage pipe of air conditioner shall be installed separately with other sewage pipe, rainwater pipe 
and drainage pipe in building. 
  The drainage pipe of the indoor unit with water pump should be apart from the one without water pump. 
6.2.4  Supporter gap of drainage pipe 
  In general, the supporter gap of the drainage pipe horizontal pipe and vertical pipe is respectively 
1m~1.5m and 1.5m~2.0m.   
  Each vertical pipe shall be equipped with not less than two hangers. 
  Overlarge hanger gap for horizontal pipe shall create bending, thus leading to air block.   
Too long distance
Gas bag
 
6.2.5  The horizontal pipe layout should avoid converse flow or bad flow 
Drainage pipe
Water flow
Drainage pipe
Drainage pipe
Drain
 
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Drain
 
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Water flow
Water flow
Water flow
Water flow
Water flow
Water flow
Water flow
Water flow
Drain
 
tee