In the following sections, the frequency of transverse vibrations of various systems and the phenomenon of whirling speed have been discussed. Natural Frequency of Free Transverse Vibrations Consider a shaft of negligible mass, whose one end is fixed and the other end carries a body of weight W, as shown in Fig (a). Fig (b)
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Step 1 : The delivery valve is closed and the suction pipe, casing and portion of the delivery pipe up to the delivery valve are completely filled with the liquid so that no air pocket is left. This process is called priming a Centrifugal Pump. Step 2 : The electric motor is started to rotate
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Most of the conventional pressure gauges are of a mechanical type. These gauges embody on elastic element which deflects under the action of the applied pressure. This movement mechanically magnified and read with the help of pointer and graduated scale. These pressure gauges are generally used for measuring high pressures and where the high precision
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The thermistor is a semiconductor device that has a negative temperature coefficient of resistance. Thermistors are non-metallic resistors, that is, semiconductors of ceramic materials. Basic Principle : The basic principle involved in thermistor is, when it is subjected to a temperature change, the resistance of the thermistor changes. This change in resistance will be the
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The most common method of temperature measurement uses the thermocouples. It is based on seeback effect. The thermocouple temperature measurement is based on creation of an electromotive force (e.m.f). Basic Principle : The basic principle of thermocouple is when two dissimilar metals are joined together an e.m.f will exist between the two points A and
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The pressure thermometer temperature measurement is based on fluid expansion. Fluid expansion thermometer represent one of the most economical, versatile, and widely used devices for industrial temperature measurement applications. Basic principle : The basic principle in pressure thermometers are when liquids, gases or vapours are heated, they will expand, when they are cooled, it will
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This method refers to the identification of the temperature of a surface with the colour of the radiation emitted. The optical pyrometer compares the brightness of the image produced by the temperature source with that of a reference temperature lamp. The optical pyrometer has an eyepiece at one end and an objective lens on the
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These pyrometers absorb only infra red pyrometer rays and measure temperature. At some high temperature, a surface starts emitting I-R rays in addition to visible light energy. These I-R rays are used with a detector and electronic circuit to measure the temperature. Various types of photo electric transducers are used for I-R transducers. One among
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Thermal radiation pyrometers is electro magnetic radiation emitted by a body as a result of its temperature. Thermal radiation is in the wavelength region from about 0.1 to 100µm. The total radiation emitted by a blackbody is given as, Eb = σ x T4 Where, σ ⇒ Stefan boltzman constant = 5.669 x 10-8 W/m² K
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For calibration of temperature measuring devices, a constant temperature source should be provided. The temperature source should as a minimum be stable enough to provide a constant temperature. (approximately ±0.2°F) for a short length of time at any temperature. The temperature source should have a zone of uniform temperature into which the temperature measuring devices
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