Fluid End Theory

Pumping Cycle Unlike the relatively smooth, continuous flow of fluid through a centrifugal pump, the flow of fluid through a power pump occurs in a transitory dynamic condition called a pumping cycle. The event that initiates this cycle is the linear movement of the plunger or piston. In Figure 5, r is the radius of the crank in feet (meters), L is the length of the connecting rod in feet (meters), C equals L / r, and « equals (2p / 60) X rpm. Thus, X, the linear movement of the piston or plunger is

As the plunger (or piston) withdraws from the fluid cylinder or pumping chamber, the volume of the cylinder increases. The pressure in the cylinder decreases in response to the increased volume. Since most of the fluids handled by power pumps are relatively incompressible, very little plunger movement is required to cause a pressure drop. When the cylinder pressure drops sufficiently below suction pressure, the differential pressure begins to open the suction valve. The valve opens gradually and smoothly at the start of the suction stroke because the velocity and acceleration of the plunger are small.

Fluid flows through the suction valve assembly, following the plunger and filling the cylinder. As the plunger decelerates at the end of the suction stroke, the suction valve gradually returns to its seat. Ideally, the suction valve is completely closed as the plunger comes to a stop.

The motion of the slider-crank mechanism causes the plunger to reverse direction and start its discharge stroke. The fluid trapped in the fluid cylinder is compressed until the cylinder pressure exceeds the discharge pressure by an amount sufficient to begin to open the discharge valve. As with the suction valve, the discharge valve continues to open until it reaches its travel limit or until the velocity of fluid through the valve becomes constant. As the plunger decelerates, the valve moves back toward its seat. Again, ideally, the discharge valve closes when the motion of the plunger stops.

The number of pumping cycles in a single revolution of the crankshaft is the same as the number of cylinders in the pump. Every cylinder will "pump" in a sequence determined by the "firing order" of the crankshaft. The cylinders are arranged in parallel, with each one discharging into a common discharge manifold. In industry terms, the pump is usually identified by the number of plungers or pistons on the crankshaft. They are the same for single- or double-acting pumps (see Table 7).

Pulsations The pulsating characteristics of the fluid flowing into and out of power pumps are significantly influenced by the number of plungers or pistons. Discharge flow pulsations are the most critical because of the high energy potential generated when the system resistance reacts with the flow to create pressure. Since the magnitude of the discharge pulsation is mostly affected by the number of cylinders, increasing the number of cylinders will reduce the flow pulsations.

End of Days Apocalypse

End of Days Apocalypse

This work on 2012 will attempt to note them allfrom the concepts andinvolvement by the authors of the Bible and its interpreters and theprophecies depicted in both the Hopi petroglyphs and the Mayan calendarto the prophetic uttering of such psychics, mediums, and prophets asNostradamus, Madame Blavatsky, Edgar Cayce, and Jean Dixon.

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