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MODULE 1. FLUIDS MECHANICS

MODULE 2. PROPERTIES OF FLUIDS

MODULE 3. PRESSURE AND ITS MEASUREMENT

MODULE 4. PASCAL’S LAW

MODULE 5. PRESSURE FORCES ON PLANE AND CURVED SUR...

MODULE 6.

MODULE 7. BUOYANCY, METACENTRE AND METACENTRIC HEI...

MODULE 8. KINEMATICS OF FLUID FLOW

MODULE 9: CIRCULATION AND VORTICITY

MODULE 10.

MODULE 11.

MODULE 12, 13. FLUID DYNAMICS

MODULE 14.

MODULE 15. LAMINAR AND TURBULENT FLOW IN PIPES

MODULE 16. GENERAL EQUATION FOR HEAD LOSS-DARCY EQ...

MODULE 17.

MODULE 18. MAJOR AND MINOR HYDRAULIC LOSSES THROUG...

MODULE 19.

MODULE 20.

MODULE 21. DIMENSIONAL ANALYSIS AND SIMILITUDE

MODULE 22. INTRODUCTION TO FLUID MACHINERY

## LESSON 26. EMPRICAL EQUATIONS FOR FRICTION HEAD LOSS

### Hazen-Williams equation:

It was developed for water flow in larger pipes (D≥5 cm, approximately 2 in.) within a moderate range of water velocity (V≤3 m/s, approximately 10 ft/s). Hazen-Williams equation, originally developed for the British measurement system, has been written in the form

S= slope of the energy grade line, or the head loss per unit length of the pipe (S=hf/L)

Rh = the hydraulic radius, defined as the water cross sectional area (A) divided by wetted perimeter (P). For a circular pipe, with A=πD^{2}/4 and P=πD, the hydraulic radius is

CHW= Hazen-Williams coefficient. The values of CHW for commonly used water-carrying conduits are given in Table 1.2.

The Hazen-Williams equation in SI units is written in the form of

Velocity in m/s and Rh is in meters

### Manning’s Equation

Manning equation has been used extensively open channel designs. It is also quite commonly used for pipe flows. The Manning equation may be expressed in the following form:

n= Manning’s coefficient of roughness. Typical values of n for water flow in common pipe materials is given in Table 1.3

In British units, the Manning equation is written as

Where V is units of ft/s.