Heads formula

The term pump head represents the net work performed on the liquid by the pump. It is eomposed of four parts. They are the statie head (Hs), or elevation the pre.ssure head (Hp) or the pre.ssures to be overcome the friction head (Hf) and velocity head (Hf), which are frictions and other resistances in the piping system. These heads are discussed in Chapter 8. The head formula is the following ... 

No pump in the world can lift cold water 40 ft from an open well in a suction lift condition because the water would evaporate before it comes into the pump. The rca.son lies in the basic head formula ... 

When vapor bubbles eollapse inside the pump the liquid strikes the metal parts at the speed of sound. This is the elicking and popping noise we hear from outside the pump when we say that eavitation sounds like pumping marbles and roeks. Sound travels at 4,800 ft per second in water. The velocity head formula gives a elose approximation of the energy contained in an imploding cavitation bubble. Remember that implosion is an explosion in the opposite direction. 

You ean see, ba.sed on the veloeity head formula, a eavitation bubble impacts the impeller and other pump parts at about 155,069 psi. Other experiments in test laboratories using a more preeise rHv, have calculated the impact pressure at 1 Gigapascal, or 147,000 psi. This is the reason that the damage from eavitation appears like someone was beating on your impeller with a large ball pein hammer. 

Under general headings such as Cobalt(III) complexes and Ammines, used for grouping coordination complexes of similar types having names considered unsuitable for individual headings, formulas or names of specific compounds are not usually given. Hence it is imperative to consult the Formula Index for entries for specific complexes. 

Internal pressure, P,-. Select appropriate head formula based on head geometry. For dished only heads as in Figure 2-5, Case 3 ... 

Head types fall into one of three general categories hemispherical, torispherical, and ellipsoidal. Hemispherical heads are analyzed as spheres and were covered in the previous section. Torispherical (also known as flanged and dished heads) and ellipsoidal head formulas for stress are outlined in the following form. 

When the opening and its reinforcement are totally within the spherical part of a torispherical head, tr is determined using the hemispherical head formula with both E and M = 1.0 (see Fig. 11.13a). 

There are also handy pressure vessel formulas—calculation of head formulas with partial loaded volumes and head weights— included, making this a handy field guide. 

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