Pressure drop Total line

Pressure drop through line systems containing more than one pipe size can be determined by (a) calculating the pressure drop separately for each section at assumed flows, or (b) determining the R totals iox each pipe size sep>-arately, and then converting to one selected. size and using that for pressure drop calculations. For example, using... 

Isothermal Gas Flow in Pipes and Channels Isothermal compressible flow is often encountered in long transport lines, where there is sufficient heat transfer to maintain constant temperature. Velocities and Mach numbers are usually small, yet compressibihty effects are important when the total pressure drop is a large fraction of the absolute pressure. For an ideal gas with p = pM. JKT, integration of the differential form of the momentum or mechanical energy balance equations, assuming a constant fric tion factor/over a length L of a channel of constant cross section and hydraulic diameter D, yields,... 

Example The maximum flare load of a system is 1,000,000 Ibs/hr of vapor. The pressure at the base of the flare stack is 2 psig, the average molecular weight of the vapor is 50, at a temperature of 200°F at the combined header to the flare stack. The distance from the drum to the stack is 500 ft. The line consists of two 90° welding elbows and an orifice for a flow controller. The total pressure drop at the knock-out drum is 0.5 psi. Determine the pressure at the inlet of the knock-out drum. 

Total two-phase pressure drop, including horizontal and vertical sections of line. Use calculated... 

Calculate the pressure drop for the specific line section (or total line) from ... 

Scope, 52 Basis, 52 Compressible Flow Vapors and Gases, 54 Factors of Safety for Design Basis, 56 Pipe, Fittings, and Valves, 56 Pipe, 56 Usual Industry Pipe Sizes and Classes Practice, 59 Total Line Pressure Drop, 64 Background Information, 64 Reynolds Number, R,. (Sometimes used Nr ), 67 Friction Factor, f, 68 Pipe—Relative Roughness, 68 Pressure Drop in Fittings, Valves, Connections Incompressible Fluid, 71 Common Denominator for Use of K Factors in a System of Varying Sizes of Internal Dimensions, 72 Validity of K Values,... 

Inlet nozzles should be sized for 2.5 gpm liquid per tube with the inlet line pressure drop not to exceed 1.5 psi per 100 equivalent ft of inlet piping for total gpm. Nozzles may, in all cases, come into the side of the bottom channel. 

The use of UV light has been selected as disinfection agent in this case study. The advantages of this technique have been explained previously [27], Total inactivation of the E. coll present in the WWTP effluent was achieved, as can be seen in Table 4 and pressure drop in the water line was increased in 0.1 bar. 

Figure 5-1 illustrates a method that will produce a system in which the parts fit together to accomplish the common goal of good control. Control valve share of total system flowing pressure drop will be 60% at normal flow. The system will still achieve maximum flow as long as the control valve trim selected can pass maximum flow at operating head loss (line 23 of Figure 5-1). The procedure described in Figure 5-1 is intended as a stand-alone device for guiding the calculations, and worksheets can be prepared from it.

The core - flood apparatus is illustrated in Figure 1. The system consists of two positive displacement pumps with their respective metering controls which are connected through 1/8 inch stainless steel tubing to a cross joint and subsequently to the inlet end of a coreholder 35 cm. long and 4 cm. in diameter. Online filters of 7 im size were used to filter the polymer and brine solutions. A bypass line was used to inject a slug of surfactant solution. Two Validyne pressure transducers with appropriate capacity diaphragms are connected to the system. One of these measured differential pressure between the two pressure taps located about one centimeter from either end of the coreholder, and the other recorded the total pressure drop across the core and was directly connected to the inlet line. A two - channel linear strip chart recorder provided a continuous trace of the pressures. An automatic fraction collector was used to collect the effluent fluids. 

Example 7-3 Flow in a Manifold. A manifold, or header, distributes fluid from a common source into various branch lines, as shown in the Fig. 7-7. The manifold diameter is chosen to be much larger than that of the branches, so the pressure drop in the manifold is much smaller than that in the branch lines, ensuring that the pressure is essentially the same entering each branch. However, these conditions cannot always be satisfied in practice, especially if the total flow rate is large and/or the manifold is not sufficiently larger than the branch lines, so the assumptions should be verified. 

The installed valve characteristic. This depends upon the ratio of the pressure drop through the valve to the total pressure drop across the whole process line installation including the valve. If a valve of linear sensitivity is handling the entire system pressure drop, then its installed characteristic will also be linear. As the percentage of the pressure drop falls off, the installed characteristic rapidly changes to that of an on-off valve. The increasing-sensitivity valve also loses its characteristic in the same way, but to a far lesser extent. Hence, this type of valve is frequently chosen in preference to the linear type. Peters(U> has discussed the effects of choosing valves with incorrect characteristics. 

Critical quality attributes and operating parameters should be documented and monitored. The program may include a combination of in-line sensors or recorders (e.g., a conductivity meter and recorder), manual documentation of operational parameters (such as carbon fdter pressure drop), and laboratory tests (e.g., total microbial counts). The frequency of sampling, the requirement for evaluating test results, and the necessity for initiating corrective action should be included. 

Eqn (23) is a second order nonlinear difference equation the Jacobian of which is easily established as a regular tridiagonal matrix with a dominating diagonal, similar to system matrices found in the simulation of distillation columns. The analytical derivation of the Jacobian and the Newton-Raphson iteration is trivial. In figure 3 is shown an example where the intermediate pressures are plotted as functions of the total pressure drop across the line segment. The example is artificially chosen such that all e-parameters are the same, i.e. ... 

If the total pressure drop increases, choked flow will occur in one of the restrictions along the line, usually the last. 

A tube bank uses an in-line arrangement with S = Sp = 1.9 cm and 6.33-mm-diameter tubes. Six rows of tubes are employed with a stack 50 tubes high. The surface temperature of the tubes is constant at 90 C, and atmospheric air at 20°C is forced across them at an inlet velocity of 4.5 m/s before the flow enters the tube bank. Calculate the total heat transfer per unit length for the tube bank. Estimate the pressure drop for this arrangement. 

The pressure drop in a process is the summation of the pressure drop in the lines, that contributed by two control valves, the pressure drop in the column, and the pressure drop in the condenser. What is the precision of the calculated total pressure drop in psia calculated at a 95 percent confidence level for the following data ... 

Fig. 9. Pressure drop-flow rate curves of Manurung (M7). 1, AP total 2, AP upper 3, AP lower solid lines, increasing flow dashed lines, decreasing flow.

Fig. 6 shows the variation in and residual pressure drop during six hours of operation. K is calculated from Eq. 4. Calculated mean specific cake resistance equals 6.5-10 [s ], with a standard deviation of approx. 15%. is defined as the velocity across the exposed filter surface (vy 2 U,). Observed fluctuations in pressure build-up did not result in any increase in the residual pressure drop. The residual pressure drop could be maintained at a constant level. The average filtration efficiency was 0.9983. Filter regeneration was conducted with off-line pulsing (P,a = 2barg and total sand spill of 10 kg). 

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