June 2021

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

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

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

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

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

Filled systems temperature is by expansion of gases and liquids when it is heated and contraction of the same when it is cooled. Fig shows a filled systems. The pressure bulb contains thermometer fluid. This is connected to a receiving element by a capillary. The bulb is kept in the place where temperature is to

Laser Doppler Anemometer enables the measurement of instantaneous velocity of a gas or a liquid flowing in a glass walled channel. It offers the non-disturbance advantages of optical methods while affording a very precise quantitative measurement of local flow velocity. This instrument is the most recent advancement in the area of flow measurement especially measurement

A float technique is a small object lighter than water and thus capable of floating on the water surface. It is usually made of wood or other suitable material. Floats are used to measure the velocity of flow of water in rivers and channels. It is the simplest method in measuring velocity of flow at

A current meter is used to measure the velocity of flow in the channel. It consists of a wheel or revolving element on which the conical buckets of V-shaped vanes are fixed. So, the current meters are classified on the basis of revolving element such as Cup type current meter. Screw or propeller type current

Tactile pressure sensors are used to detect the pressure distribution between a sensor and a target. They are often used on the robot grippers or flat tactile arrays to identify whether the finger is in touch with the target object or not. These sensors are also used in touch screen display of laptops, ATM machines,