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Introduction to Fluid Power by Mike Pierno. Pascal’s Law. Pascal’s Law, simply stated, says this: Pressure applied on a confined fluid is transmitted undiminished in all directions, and acts with equal force on equal areas and at right angles to them. F = P x A. HOW PRESSURE IS CREATED
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Introduction to Fluid Power by Mike Pierno
Pascal’s Law Pascal’s Law, simply stated, says this: Pressure applied on a confined fluid is transmitted undiminished in all directions, and acts with equal force on equal areas and at right angles to them. F = P x A
HOW PRESSURE IS CREATED Pressure results whenever there is a resistance to fluid flow or to a force which attempts to make the fluid flow. The tendency to cause flow (or the push) may be supplied by a mechanical pump, compressor, or may be caused simply by the weight of the fluid.
Pressure “head” comes from the weight of the fluid. Atmospheric pressure is a “head” of air.
Force is Proportional to Pressure and Area F P A These Pressure, Force and Area relationships are sometimes illustrated as shown below to aid in remembering the equations. When a cylinder is used to clamp or press, its output force can be computed as follows: F = P x A Again: P is Pressure (PSI (Bar) (Pascals)) F is Force (pounds (newtons)) A is Area (Square inches (Square meters) F = P x A P = F / A A = F / P
Simple Hydraulic Lever Simple Mechanical Lever
141.3 141.3
Parallel Flow Paths List the order in which the cylinders will extend, and calculate the pressure needed to lift the load for each. 24,000 lbs. 24,000 lbs. 24,000 lbs. Cyl. Sequence PSI A B C 1st 2nd 3rd 4” bore 2” bore 6” bore
Bernoulli’s Principle Bernoulli’s Principle states that if the flow rate is constant, the sum of the kinetic ands pressure energy must be constant. Therefore, if the kinetic energy decreases, it must result in an increased pressure. Likewise, when the cross-sectional area of the flow path decreases, the kinetic energy (velocity) produces a corresponding decrease in pressure.
Laminar flow is in parallel paths. Turbulence results in flow resistance.
Velocity is inversely proportional to pipe cross-sectional area
Introduction to Fluid Power by Mike Pierno