2019-10-30T14:15:49+03:00[Europe/Moscow] en true Pressure, Force exerted per unit area, Pressure, Atmospheric Pressure, Atmospheric Pressure, Head, Hydrostatic Pressure, Hydrostatic Pressure, Pascal's Law, Example of Pascal's Law, Absolute Pressure, When measuring absolute pressure, Absolute Pressure, Gauge Pressure, Vacuum Pressure, Differential Pressure, Manometer, Inclined-tube manometer, Well-type manometer, Well drop, Barometer, Diaphragms, Capsule, Bourdon tubes, Pressure Spring, Bellows, Double-ended piston, Transducer, Pressure Transmitter, Pressure Switch, Resistance Pressure Transducer, Capacitance pressure transmitter, A differential pressure (d/p) cell, Inductance pressure, LVDT, Stress, Strain, Dry Leg, Wet Leg, Dead weight tester flashcards
Pressure & Pressure Measurement

Pressure & Pressure Measurement

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  • Pressure
    is a type of stress which is exerted uniformly in all directions.
  • Force exerted per unit area
    P = F/A P = Pressure in Pascal (lb/inch) F = Force in Newton (lb) A = Area in square meter
  • Pressure
    Increases as force increases or area decreases.
  • Atmospheric Pressure
    is the pressure due to weight of the atmosphere above the point where it is measured.
  • Atmospheric Pressure
    changes at different elevations because at higher elevation there is less weight of air than lower elevation areas.
  • Head
    is the actual height of the column of liquid. A container or vessel can be any shape but head is only determined by the height of liquid.
  • Hydrostatic Pressure
    is the pressure due to head of liquid column.
  • Hydrostatic Pressure
    P = ph P = pressure in (Pa or in psi) p = density (kg/cu m or lb/cu in) h = height (in m or feet)
  • Pascal's Law
    is stating that the pressure applied to a confined static fluid is transmitted equal intensity throughout the fluid.
  • Example of Pascal's Law
    A hydraulic press
  • Absolute Pressure
    is pressure measured with a perfect vacuum as the zero point of the scale.
  • When measuring absolute pressure
    the units increase as the pressure increases.
  • Absolute Pressure
    cannot be less than zero and is unaffected by changes in atmospheric pressure.
  • Gauge Pressure
    is pressure measured with atmospheric pressure as zero point of scale. Negative gauge pressure is gauge pressure that is less than atmospheric pressure.
  • Vacuum Pressure
    is the pressure measured below atmospheric pressure, referenced to atmospheric pressure.
  • Differential Pressure
    is the difference in pressure between two points of measurement.
  • Manometer
    is a device for measuring pressure with a liquid filled tube.
  • Inclined-tube manometer
    is a manometer with a reservoir serving as one end and the measuring column at an angle to the horizontal to reduce the vertical height.
  • Well-type manometer
    is a manometer with a vertical glass tube connected to a metal well, with the measuring liquid in the well at the same level as the zero point on the tube scale
  • Well drop
    is the ratio of the area of a well-type manometer tube to the area of the well.
  • Barometer
    is a manometer used to measure atmospheric pressure.
  • Diaphragms
    are a mechanical pressure sensor consisting of a thin flexible disc that flexes in response to a change in pressure.
  • Capsule
    is a mechanical pressure sensor consisting of two convoluted metal diaphragms with their outer edges welded to provide an empty chamber between them.
  • Bourdon tubes
    provide fairly large displacement motion that is useful in mechanical pressure gauges; the lesser motion of diaphragms is better in electromechanical sensors.
  • Pressure Spring
    is a mechanical pressure sensor consisting of a hollow tube formed into a helical, spiral, or C shape.
  • Bellows
    is a mechanical pressure sensor consisting of a one-piece, collapsible, seamless metallic unit with deep folds formed from thin-wall tubing with an enclosed spring to provide stability, or with an assembled unit of welded sections
  • Double-ended piston
    is a mechanical pressure sensor consisting of a differential pressure gauge with a piston that admits pressurized fluid at each end.
  • Transducer
    is a device that converts input energy into an output electrical energy.
  • Pressure Transmitter
    is a pressure transducer with power supply and a device that conditions and converts the transducer output into a standard analog or digital output.
  • Pressure Switch
    provides a discrete output when applied pressure reaches a preset level within the switch.
  • Resistance Pressure Transducer
    is a diaphragm pressure sensor with a strain gauge as the electrical output element.
  • Capacitance pressure transmitter
    is a diaphragm pressure sensor with a capacitor as the electrical element.
  • A differential pressure (d/p) cell
    converts a differential pressure to an electrical (4 - 20mA) output signal.
  • Inductance pressure
    transducer is a diaphragm or bellows pressure sensor with electrical coils and movable ferrite core as the electrical element.
  • LVDT
    is an inductance transducer consisting two coils wound on a single nonconductive tube.
  • Stress
    is the internal distribution of forces within a body that balance and react to the loads applied to it.
  • Strain
    is a fractional change in the dimensions of an object as a result of mechanical stress.
  • Dry Leg
    impulse line that is filled with a non-condensing gas
  • Wet Leg
    an impulse line filled with fluid that is compatible with the pressure-measuring device
  • Dead weight tester
    is a hydraulic pressure calibrating device that includes a manually operated screw press, a weight platform supported by a piston, a set of weights, and a fitting to connect the tester to a gauge.