Collapsing pressure

Neumann has adapted the pendant drop experiment (see Section II-7) to measure the surface pressure of insoluble monolayers [70]. By varying the droplet volume with a motor-driven syringe, they measure the surface pressure as a function of area in both expansion and compression. In tests with octadecanol monolayers, they found excellent agreement between axisymmetric drop shape analysis and a conventional film balance. Unlike the Wilhelmy plate and film balance, the pendant drop experiment can be readily adapted to studies in a pressure cell [70]. In studies of the rate dependence of the molecular area at collapse, Neumann and co-workers found more consistent and reproducible results with the actual area at collapse rather than that determined by conventional extrapolation to zero surface pressure [71]. The collapse pressure and shape of the pressure-area isotherm change with the compression rate [72]. 

Failure of vacuum Design vessel to accommodate maximum system control vacuum (full vacuum rating) resulting in possi-. , elief system bility of vessel collapse pressure alarm and interlock to inert gas supply Select/design vacuum source to limit vacuum capability ASME VIII CCPS G-23 CCPS G-39... 

Static The fan total pressure minus the dynamic pressure corresponding to the mean air velocity at the fan outlet. The fan static pressure is the bursting or collapsing pressure on the enclosure,... 

During DST operations, the drill pipe may be affected by a combined effect of collapse pressure and tensile load. For such a case,... 

Equation 4-65 indicates that increased tensile load results in decreased collapse pressure resistance. The decrement of collapse pressure resistance during normal DST operations is relatively small nevertheless, under certain conditions, it may be quite considerable. 

From Table 4-84, the collapse pressure resistance in uniaxial state of stress, P - 6,010 psi. Reduced wall thickness for class 2 drill pipe = (0.65)(0.337) = 0.219 in. Reduced D for class 2 drill pipe = 3.826 + (2)(0.219) = 4.264 in. Reduced cross-sectional area of class 2 drill pipe equals ... 

The corrected collapse pressure resistance according to Equation 4-65 is... 

Yield Strength Collapse Pressure Formula. The yield strength collapse pressure is not a true collapse pressure but rather the external pressure p that generates minimum yield stress on the inside wall of a tube as calculated by... 

Plastic Collapse Pressure Formula. The minimum collapse pressure for the plastic range of collapse is calculated by... 

The formula for minimum plastic collapse pressure is applicable for D/t values as shown in Table 4-151. The factors A, B, and C are given in Table 4-152. 

The factors F and G and applicable D/t range for the transition collapse pressure formula are shown in Tables 4-152 and 4-151, respectively. 

Collapse Pressure under Axial Tension Stress. The reduced minimum collapse pressure caused by the action of axial tension stress is calculated by... 

Collapse Assumed external fluid pressure gradient of 0.52 psi/ft and casing empty inside. Safety factor for collapse = 1.0. Reduction of collapse pressure resistance due to the axial load is considered. 

Steel grade Unit weight (Ib/ft) Cross-sectional sraa (In.) Collapse pressure resistance Burst pressure resistance Joint strength (10> lb) Pipe body strength (10> lb)... 

Part 1. Consider collapse pressure and tension load. 

Step 1. Determine the lightest weight of casing to resist collapse pressure for a setting depth of 12,000 ft. Because the maximum collapse pressure is (12,000)(0.52) = 6,240 psi, select N-80, 29-lb/ft casing with collapse pressure resistance of 7,020 psi. (Note assumed safety factor for collapse = 1.0.) This is Section 1. 

For this axial load, the reduced minimum collapse pressure resistance of Section 2 can be calculated from formula 4-312. 

Yin et al. [73,74] prepared new microgel star amphiphiles and stndied the compression behavior at the air-water interface. Particles were prepared in a two-step process. First, the gel core was synthesized by copolymerization of styrene and divinylbenzene in diox-ane using benzoylperoxide as initiator. Microgel particles 20 run in diameter were obtained. Second, the gel core was grafted with acrylic or methacryUc acid by free radical polymerization, resulting in amphiphilic polymer particles. These particles were spread from a dimethylformamide/chloroform (1 4) solution at the air-water interface. tt-A cnrves indicated low compressibility above lOmNm and collapse pressnres larger than 40 mNm With increase of the hydrophilic component, the molecnlar area of the polymer and the collapse pressure increased. 

If the power dissipated into the system is increased, although the collapse pressure, as predicted using bubble dynamics analysis [14], decreases with an increase in the intensity, the number of cavitation events also increases (increase is substantial as compared to the negative effect of decreasing collapse pressure) thereby increasing the overall cavitational activity and hence enhanced effects can be observed. Usually the increase in number of cavities generated seizes after a... 

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