Static head

This is the overall height to which the liquid must be raised. 

Discharge static head H (from centerline of pump) Suction static head S, (actually +S) 

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Fig. 6. Illustration of variation of velocity of air at the oudet of a centrifugal fan and the function filled by several diameters of straight discharge duct in converting velocity head to static head and estabUshing normal turbulent dow distribution. Bends or obstmctions at the discharge oudet cause turbulence...

The scale-up of filtration centrifuges is usually done on an area basis, based on small-scale tests. Buchner funnel-type tests are not of much value here because the driving force for filtration is not only due to the static head but also due to the centrifugal forces on the Hquid in the cake. A test procedure has been described with a specially designed filter beaker to measure the intrinsic permeabiHty of the cake (7). The best test is, of course, with a small-scale model, using the actual suspension. Many manufacturers offer small laboratory models for such tests. The scale-up is most reHable if the basket diameter does not increase by a factor of more than 2.5 from the small scale. 

Pressure Drop. The pressure drop across a two-phase suspension is composed of various terms, such as static head, acceleration, and friction losses for both gas and soflds. For most dense fluid-bed appHcations, outside of entrance or exit regimes where the acceleration pressure drop is appreciable, the pressure drop simply results from the static head of soflds. Therefore, the weight of soflds ia the bed divided by the height of soflds gives the apparent density of the fluidized bed, ie... 

Static Discharge Head The static discharge head is the vertical distance measured from the free surface of the hquid in the receiver to the pump centerhne, plus the absolute pressure at the hquid surface. Total static head hf, is the difference between discharge and suction static heads. 

FIG. 10-33 Variation of total head as a function of flow rate to overcome both friction and static head. 

The rated discharge is at a static head of /7j and a motor h.p. P. In the process of controlling the discharge from Q to and Qy, the valve is throttled, which increases the head loss of the system (or system resistance) from A/ji to and H,yy respectively. The operating point on the curve now shifts from point A[ to /It... 

Hs = Static head in feet (positive or negative) of the fluid level in the suction vessel to the pump centerline. 

The Hs, static head, is the static height in feet observed from the level in the vessel to be drained to the centerline of the pump. If the... 

The curve of the pump in this service should show a NPSHr of less than 14 feet at the duty point. The purpose of this pump is to drain this tank down to 14 feet below the pump without eavitating. Let s consider a second static head, Hs-, of-14 feet. The other factors would remain the same ... 

Hs Static Head. It is the level in the d-a tank above the pump centerline. This is normally about 12 to 15 ft. 

I. Hs - the static head, or the change in elevation of the liquid across the system. It is the difference in the liquid surface le el at the suction source or ve.s.sel, subtracted from the liquid surface level where the pump deposits the liejuid. The Hs is measured in feet of elevation change. Some systems do not have Hs or elevation... 

One component of the TDH is the Hs, the static head. In this example the surface level in the discharge tank is 115.5 ft above the pump centerline. The surface level in the suction tank is 35.5 ft above the pump centerline. The AHs, by observation is 80 ft. See Figure 8-6. 

Static head generated by a centrifugal blower depends on RPM alone for a given internal construction and a given set of dimensions. Pressure generated depends not only on RPM, but also on the density of the fluid. Flow depends on conditions outside the blower and so does the power needed. Therefore, blower performance should be characterized first by the head as a function of RPM thereafter, studies can be extended to describe the flow. 

The degree of reaction in an axial-flow compressor is defined as the ratio of the change of static head in the rotor to the head generated in the stage... 

The change in static head in the rotor is equal to the change in relative kinetic energy ... 

For a saturated (bubble point) liquid, pipe vertically downward from the drawoff nozzle as close to the nozzle as possible. This gives maximum static head above any horizontal sections or piping networks ahead of the pump. 

Reaction is defined as the ratio of the static head converted in the impeller to the total head produced by the stage. Restating in a more philosophical sense, the object of the compressor stage is to increase pressure of the gas stream, and reaction gives the relationship of the divi-L.. fort between the impeller and the diffuser. 

The tank should be placed at an elevation that provides a static head less than the low oil pressure trip switch setting so as to not interfere v illi the normal trip function. Normally this means that the static head should not be more than the equivalent of 5 psi. The minimum sizing should he based on a three-minute rundown cycle. Adding a bit more to the time is probably not all that costly. 

Set Pressure - The set pressure (the pressure at whieh the PR valve is designed to open) is speeified in accordance with Code requirements. In most vessel apphcations, the set pressure of at least one PR valve is equal to the design pressure. However, this set pressure is adjusted (up or down) for any effect of static pressure and friction pressure drop that may apply when the valve is installed elsewhere than directly on the vessel. For example, if a PR valve is installed in a non-flowing line above a liquid-filled vessel, the PR valve set pressure would be reduced sufficiently to allow for the liquid static head between the vessel and the valve. 

The method includes the mass unit vent flow capacity per unit area. G. This allows using any applicable vent capacity calculation method. The method incorporates the equilibrium rate model (ERM) for vent flow capacity when friction is negligible. Additionally, a coiTection factor is used for longer vent lines of constant diameter and with negligible static head change. ... 

As the potential energy term has an essential meaning in hydromechanics, the static head is selected as a comparison quantity. When the energy equation (4.32) is divided by g and integrated, it gives the Bernoulli flow tube equation... 

Static head The difference between the total fluid pressure and the dynamic pressure. 

Friction head loss develops as fluids flow through the various pipes, elbows, tees, vessel connections, valves, etc. These losses are expressed as loss of fluid static head in feet of fluid flowing. 

The average or mean velocity is determined by the flow rate divided by the cross section area for flow in feet per second, v. The velocity in a pipe is related to the decrease in static head due to the velocity only bv ... 

Cj = discharge coefficient for nozzles and orifices hL = differential static head or pres.sure loss across... 

A = cross section area of orifice, nozzle or pipe, sq ft h = static head loss, ft of fluid flowing AP = differential static loss, Ibs/sq in. of fluid flowing, under conditions of Al above... 

For compressible fluids flowng through nozzles and orifices use Figures 2-17 and 2-18, using hL or AP as differential static head or pressure differential across taps located one diameter upstream at 0.5 diameters dow nstream from the inlet face of orifice plate or nozzle, when values of C are taken from Figures 2-17 and 2-18 [3]. For any fluid ... 

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