The fire department needs information on friction losses occurring between a water main and an open fire hydrant. at maximum main pressure (85 psig), the water discharge rate is 1620 gpm through a 2.5-inch open fire hydrant. the water main, in which the velocity is very small, is situated 8 ft below the hydrant discharge point. determine the friction loss from the main to the discharge point. assume atmospheric pressure is 15 psia.

Explanation:

The given data is as follows.

      = 85 psig,   = = 15 psia

        Q = 1620 gpm,  d = 2.5 inch,     l = 8 ft = 2.4384 m

According to Darey-Weisbach equation,

                         ......... (1)

Value of 'f' will be decided on the basis of Reynold number.

As, it is known that

where,   = kg/ms

As it is known that 1 gpm =

So,   = 3.67 gpm

Therefore,   Q =

                        =

                         = 0.1226

In, 1 inch = 2.54 cm = 0.0254 m

Therefore, d = 2.5 \times 0.0254 = 0.0635 m

                V =

                    =

                    = 38.73 m/s

Hence, we will calculate Reynold number as follows.

              =

                             = 2459355

As > 2000 then, it means that flow is turbulent.

As, f = 0.079

        = 0.001994

Putting all the values into equation (1) formula as follows.    

                                     =

                                      =

Thus, we can conclude that friction loss from the main to the discharge point is .

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.