Fluid Flow Basics & ExamplesDownload this file as a pdf
The charts and formulas here will enable you to answer
basic flow problems involving industrial hose. It contains
the necessary information for dealing with various kinds of
liquid and air. In general terms, this publication will enable
you to determine:
To obtain these answers, the charts and formulas here relate the basic variables involved with flow: Type of fluid, flow rate, available pressure (or pressure loss), hose size (I.D.) and length.
Suggestions for Chart Usage and Related Data
*Absolute Viscosity; Poise, Centipoise
Examples Using Charts
What pressure loss will result if 500 gallons per minute of water is pumped through a 3" inside diameter x 150' length of hose consisting of three 50' coupled lengths.
|a)||From Chart #2, "Flow of Water Through Hose, 1-1/2" through 4" Inside Diameter", at 500 gpm, pressure loss per 100' of 3" I.D. hose is 20 psi.|
|b)||Pressure loss is directly proportional to hose length. Since the flow charts are based on 100' lengths, loss for 100' must be converted to 150' of hose. Pressure loss for 100' of hose is 20 psi, therefore, the loss in 150' of hose is: 150'/100' x 20 psi = 30 psi.|
|c)||As a rule of thumb, loss for each set of couplings equals 5% of the loss per 100' of hose. Therefore, pressure loss = .05 x 20 psi = 1 psi per set of couplings.|
|d)||Pressure loss from three sets of couplings = 3 x 1 psi = 3 psi.|
|e)||Total pressure loss: 30 psi (hose loss) + 3 psi (coupling loss) = 33 psi pressure loss per 150' of hose.|
A pump transmits water through 3" inside diameter x 200' hose at a flow rate of 1000 gallons per minute to a traction machine requiring 120 psi to operate. What inlet pressure is necessary to assure the operation of the machine?
|a)||From Chart #2, "Flow of Water Through Hose, the pressure loss at a flow rate of 1000 gpm is 70 psi per 100' of hose.|
|b)||Flow charts are based on 100' hose lengths, so loss for 100' must be converted to 200' of hose. If pressure loss for 100' of hose is 70 psi, the loss for 200' of hose would be 200'/100' x 70 psi = 140 psi.|
|c)||Couplings are internal expansion type which are considered nonrestrictive.|
|d)||Since the machine requires 120 psi to operate, inlet pressure must be at least 260 psi. (140 psi loss from hose + 120 psi required by machine).|
Pressure loss in a 6" inside diameter x 100' hose is 40 psi while unloading gasoline with viscosity of .476 centipoise at a flow rate of 6000 gallons per minute. What difference in pressure loss would result when using an 8" inside diameter x 70' hose with two 35' coupled lengths?
|a)||From Chart #14, "Flow of Gasoline through Hose, 4" through 16" Inside Diameter", the pressure at a flow rate of 6000 gpm is 10 psi per 100' of 8" I.D. hose.|
|b)||Flow charts are based on 100' lengths and pressure loss is directly proportional to length, therefore, pressure loss in only 70' of hose is 70'/100' x 10 psi = 7 psi loss.|
|c)||As a rule of thumb, loss for each set of couplings equals 5% of the loss per 100' of hose. For each set of couplings = .05 x 10 psi loss per 100' hose = .5 psi loss per set of couplings.|
|d)||For two sets of couplings, loss = 2 x .5 psi = 1 psi.|
|e)||Total pressure loss: 7 psi (hose loss) + 1 psi (coupling loss) = 8 psi loss per 70' hose.|
|f)||The difference in pressure loss is: 40 psi (100' of 6" I.D.) - 8 psi (70' of 8" I.D.) = 32 psi. Therefore, pressure loss is decreased by: (40 psi - 8 psi)/40 psi x 100 = 80% in this case.|
Estimate the pressure loss in a 1-1/2" inside diameter x 100' hose handling Kerosene with viscosity of 2.9 centipoises and .80 specific gravity at a flow rate of 150 gallons per minute. Note: Following flow charts do not include Kerosene.
|a)||Since Fuel Oil, Chart #5, "Flow of Fuel Oil through Hose, 3/4" through 3" Inside Diameter", (viscosity = 2.6 centipoise, specific gravity = .87) has similar viscosity and specific gravity to Kerosene, it can be used to estimate the pressure loss for this example.|
|b)||From Chart #5, at 10 gallons per minute, pressure loss from 1-1/2" I.D. hose is 70 psi per 100' of hose.|
|c)||If the viscosity is less, pressure loss is also less and vice versa. His is not a direct relationship, however. The difference in kinematic viscosity should be approximately 15% or greater to affect pressure loss significantly. In this example, the viscosities do not differ enough to affect pressure loss substantially.|
|d)||Specific gravity, like hose length, is proportional to pressure loss. The specific gravity is less for Kerosene than Fuel Oil in this example so pressure loss will be proportionally less also. The pressure loss for Kerosene is therefore: .80/.87 x 70 psi = 64 psi per 100' of hose.|