# Friction loss

In a previous article " Understanding pump performance curves " we learned how to determine the capabilities of a pump. For the purposes of calculating the total friction loss of a system, the sources of form friction are sometimes reduced to an equivalent length of pipe.

### Friction losses in pipes pdf

Convergence can be optimized by slight under-relaxation. The Moody Chart The Moody Chart finally provided a method of finding an accurate friction factor and this encouraged use of the Darcy-Weisbach equation, which quickly became the method of choice for hydraulic engineers. K is the sum of all of the loss coefficients in the length of pipe, each contributing to the overall head loss. Some very basic information on K values for different fittings is included with these notes and in most introductory fluid mechanics texts. Swanson, C. If we compare the same situation with using a 6-inch mainline hose, we see a total of 2, feet of head loss at 2, gallons per minute, requiring six pumps to overcome the total friction loss. Retrieved 20 October Also the Hazen-Williams equation only really gives good results when the fluid is Water and can produce large inaccuracies when this is not the case. Diameter: 8 inches Hazen-Williams Equation outputs for this scenario: 1. By definition, "Friction loss is the loss of energy or 'head' that occurs in pipe flow due to viscous effects generated by the surface of the pipe.

Elementary Mechanics of Fluids. Engineering Monograph No.

C is dependent upon several elements; e. The Colebrook—White equation was found inadequate over a wide range of flow conditions. The introduction of the personnel computer from the 's onwards reduced the time required to calculate the friction factor and pipe head loss. Example: You have a m long pipe that has an internal diameter D of 25 cm. Employ the Hazen-Williams equation to calculate the pipe's head loss. Shockling, M. Results Reference With fluid flows, the viscosity of the fluid around the surface of a pipe or duct causes loss of pressure "head" ; this is what we mean by friction loss. Also the Hazen-Williams equation only really gives good results when the fluid is Water and can produce large inaccuracies when this is not the case. Convergence can be optimized by slight under-relaxation. Large amounts of field data on commercial pipes. K is the sum of all of the loss coefficients in the length of pipe, each contributing to the overall head loss. Blevins Applied Fluid Dynamics Handbook, table , pp.

Surface roughness[ edit ] The roughness of the surface of the pipe or duct affects the fluid flow in the regime of turbulent flow. Pipe length feet 2. Some very basic information on K values for different fittings is included with these notes and in most introductory fluid mechanics texts.

In the transition domain, friction loss is sensitive to both.

## Friction loss in pipe fittings table

Surface roughness[ edit ] The roughness of the surface of the pipe or duct affects the fluid flow in the regime of turbulent flow. From this velocity and the piping characteristics, calculate Reynolds Number, relative roughness and thus friction factor. An explicit approximation provides values within one percent of Colebrook over most of the useful range. In the rough pipe domain, friction loss is dominated by the relative roughness and is insensitive to Reynolds number. V; Donnelly, R. In a previous article " Understanding pump performance curves " we learned how to determine the capabilities of a pump. This calculates to feet of head. Hazen and Williams created an empirical formula to calculate pressure losses for liquids flowing through straight pipes.

For turbulent flow, Colebrook found an implicit correlation for the friction factor in round pipes. Factors affecting the value of K include: the exact geometry of the component in question the flow Reynolds Number proximity to other fittings, etc.

The Moody Chart The Moody Chart finally provided a method of finding an accurate friction factor and this encouraged use of the Darcy-Weisbach equation, which quickly became the method of choice for hydraulic engineers.

## How do you calculate friction loss in a pipe

Here's a video discussing the three types of piping problems: "Minor Losses" Although they often account for a major portion of the head loss, especially in process piping, the additional losses due to entries and exits, fittings and valves are traditionally referred to as minor losses. Proceedings of the Royal Society of London. Diameter: 8 inches Hazen-Williams Equation outputs for this scenario: 1. By definition, "Friction loss is the loss of energy or 'head' that occurs in pipe flow due to viscous effects generated by the surface of the pipe. Figure 2 The energy efficiency of the pump is very good there or at higher flow rates. Head Loss: psi 3. Washington, D. Like pipe friction, these losses are roughly proportional to the square of the flow rate. Blevins Applied Fluid Dynamics Handbook, table , pp. Choosing from 6-inch, 7-inch or 8-inch mainline hose, we select 8-inch. The introduction of the personnel computer from the 's onwards reduced the time required to calculate the friction factor and pipe head loss. The procedures are the same except that the K values may also change as iteration progresses. To till or not to till? Some very basic information on K values for different fittings is included with these notes and in most introductory fluid mechanics texts.

Proceedings of the Royal Society of London. Blevins Applied Fluid Dynamics Handbook, tablepp.

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