Head of fluid

An important safety feature on every modern rig is the blowout preventer (BOP). As discussed earlier on, one of the purposes of the drilling mud is to provide a hydrostatic head of fluid to counterbalance the pore pressure of fluids in permeable formations. However, for a variety of reasons (see section 3.6 Drilling Problems ) the well may kick , i.e. formation fluids may enter the wellbore, upsetting the balance of the system, pushing mud out of the hole, and exposing the upper part of the hole and equipment to the higher pressures of the deep subsurface. If left uncontrolled, this can lead to a blowout, a situation where formation fluids flow to the surface in an uncontrolled manner. 

The term static bead generally denotes the pressure in a fluid due to the head of fluid above the point in question. Its magnitude is given by the apphcation of Newton s law (force = mass X acceleration). In the case of bquids (constant density), the static headp/, Pa (lbf/ft ) is given by... 

Go to a standard handbook like Perry s Chemical Engineer s Handbook and obtain several hydraulic conductivities (say for sand, crushed stone, gravel, diatomaceous earth, other). Assume a constant head of fluid over a bed of each material, and apply Darcy s law to calculate flowrates and compare the results. Try several hydraulic head calculations and plot the results. Which of the materials studied shows the highest hydraulic resistance ... 

In the example the manufacturer has been specified from available performance curves, and the details of construction must be obtained. The pump is selected to operate at 22 GPM and 196 to 200 feet head of fluid, and must also perform at good efficiency at 18 GPM and a head which has not been calculated, but w hich will be close to 196 to 200 feet, say about 185 feet. Ordinarily the pump is rated as shown on the specification sheet. This insures adequate capacity and head at conditions somewhat in excess of normal. In this case the design GPM w as determined by adding 10 percent to the capacity and allowing for operation at 90 percent of the rated efficiency. Often this latter condition is not considered, although factors of safety of 20 percent are not unusual. However, the efficiency must be noted and the increase in horsepower recognized as factors w hich are mounted onto normal operating conditions. 

Z1 2 static head of fluid above reference level, ft Two-phase flow... 

Each term on the left-hand side has the same dimensions, length (energy per unit weight of fluid) in this version of Bernoulli s Equation. Each term can be thought of as a head of fluid, and the sum of these terms is called the total head of fluid. 

Note that in some equations, the values of constants are a function of the system of units used. These constants have dimensions and are known as dimensional constants. For example, many flowmeters measure volumetric flow rates, Qv, by measuring heads of fluids, Ah. Typically, Qv oc a/Ah or Qv = csfKh. Here, as Qv[f y[Ah, c is a dimensional constant. Dimensionally, L3T-1[=] cs/L or c [=] L2 5T 1, and the value of c will depend upon the units of both Qr and Ah. 

H, h Head of fluid, height m ft R Range of reaction forces N or N mm Ibforinlbf... 

Hydrostatic head viscometers are capillary viscometers in which a hydrostatic head of fluid provides the... 

The need for maintaining subcooled liquid in the supply tank is based upon the need for net positive suction head (NPSH), which is the total head of fluid in excess of vapor pressure, at the pump inlet. Years of experience in designing and testing pumps for fluids other than hydrogen have demonstrated the need for NPSH at the pump inlet to ensure proper operation. However, test data for hydrogen suggest that unusual suction performance can be expected. This expectation is especially valid if the available thermodynamic head at the pump inlet is considered. In this case, thermodynamic head is defined as the reduction in enthalpy of the fluid when expanded isentropically. This process involves vaporization, i.e., cavitation of the fluid. 

Iowa City lA, and there submitted his PhD thesis in 1948. He then was an associate professor and later professor of civil engineering, and Head of Fluid Mechanics Research at Colorado State University CSU, Fort Collins CO. From 1857 imtil retirement,... 

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