Equivalent Length of a Pipe with Fittings and Valves

This Demonstration estimates the equivalent length of a pipe that determines the frictional pressure drop in fluid flow by converting the number of fittings and valves into an analogous length and adding it to the actual length. You enter the actual pipe's length and diameter and the type and number of fittings and valves. The corresponding equivalent pipe length, in meters, and contribution of the fittings and valves to the overall friction, in percent, are then calculated and displayed.


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Snapshot 1: 20-meter-long, 5-centimeter-diameter straight pipe without fittings or valves
Snapshot 2: 20-meter-long, 5-centimeter-diameter L-shaped pipe with a flow meter and a wide open gate valve
Snapshot 3: 10-meter-long, 10-centimeter-diameter L-shaped pipe with a flow meter and a half-open globe valve
One method of pressure drop estimation in fluid flow through pipes requires calculation of the pipe's equivalent length. This length depends on the pipe's actual length and diameter and on the type and number of fittings and valves along it. In the case of valves it also depends on whether or not they are wide open. This Demonstration calculates the equivalent length of the fittings and valves in turbulent flow and adds it to the pipe's actual length, thus rendering a total equivalent length. It also calculates the contribution of the fittings and valves to the overall friction, in percent, that is, , where is the equivalent length and the pipe's actual length, in meters.
The actual pipe's length, from 0 to 100 meters, and its diameter, from 0.25 to 25 centimeters, are entered with the top two sliders in the panel.
An assortment of common fittings and valves are listed on the left and right sides of the panel and you can enter the number of each type with a slider.
To see the contribution of any combination of fittings and valves alone, set the pipe's length slider to 0. To see the contribution of a single fitting or valve, set its number to 1 and set the pipe's length and all other fitting and valve sliders to 0.
The equivalent length in meters of any combination of slider entries and the corresponding contribution of the fittings and valves to the overall friction are displayed at the bottom of the panel.
R. H. Perry and C. H. Chilton, Chemical Engineer's Handbook, 5th ed., New York: McGraw–Hill, Inc., 1973.
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