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Pressure Drop in Hoses

 

The following tables of pressure drops and flow rates are based on experimental data and may be considered typical of most hoses. The data is based upon hoses laid out in a straight line and thus it must not be considered as an exact result that may be obtained at a given pressure. Variables such as hose fittings and bends increase the frictional losses and an estimate of their effect may be determined by adding an “equivalent length” to the hose length. Values of the equivalent length (Le) may be determined using the inside diameter (D) of the hose in the following relationships:

  • 90° swept elbow – Le = 20D
  • 90° square elbow – Le = 50D
  • 45° square elbow – Le = 16D
  • Hose coupling – Le = 5D
Pressure Drop (kPa/100m) Water at 20°C Through Hose
Flowrate
1/m
Hose Internal Diameter
12.5 16 19 25 32 38 40 50 64 75 80 100 125
25 1100 470 210 50                  
50   2440 770 200 90 30              
100     2260 730 300 100 55 30          
200         1030 405 285 95 25        
300           900 650 210 65 20      
400             1200 370 110 40      
500               580 155 70 50    
1000                 575 230 180 55  
2000                   920 600 220 45
3000                   2125 1400 490 100
4000                       805 190
5000                       1390 315
  • NOTE:(1) Pressure drop is directly proportioned to the length of hose.
  • (2) Friction is independent of pressure and proportional to velocity.
Pressure Drop of Air Through Rubber Hose
Size
(mm)
Cu./m of Free Air
0.5 1.0 1.25 1.5 2.0 2.75 3.5 4.25
12.5 249 855 1325 - - - - -
19 - 215 350 505 895 1725 2745 -
25 - - - - 250 465 755 1100
32 - - - - 80 100 175 285
38 - - - - - 45 75 135
Size
(mm)
Cu./m of Free Air
15 20 30 40 50 60 70 80 90 100 125 150
50 385 680 1530 2690 4230 - - - - - - -
64 160 270 565 1020 1630 2350 3170 4185 5270 - - -
76 - - 215 330 520 745 1020 1335 1675 2035 3190 4590

To obtain frictional pressure loss in kPa/100m divide above values by the ratio of compression listed here:

KPa W.P. Ratio of Compression
400 3.9
500 4.9
600 5.9
700 6.9
800 7.85
900 8.85
1000 9.85

Pressure Loss - Layflat Hose

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