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An instrument called as Pyrometer used for measure temperature. Pyrometer measure the temperature of the surface of objects. The pyrometers designed to measure high temperature neither low temperature. The measurement also can be very accurate. Its measure the amount of thermal energy emerging from a body by radiation temperature of the body. A fixed lens in Pyrometer measure the temperature by sensing the heat radiated from hot substances.
Instruments for temperature measurement by radiation are called radiation thermometers. This is an suitable property for the non-contact since the energy radiated by an object is a function of its absolute temperature. There are four principal techniques for the measurement of temperature by the radiation from a hot body:
1. Total radiation,
4. Optical Pyrometers
Total Radiation Pyrometers
The radiation emitted by the radiant body or fluid whose temperature is to be measured is focused on a thermal receiving surface. The element receiving have mixture forms. It could be the resistance element. It is generally in the form of blackened platinum, thermopile or thermocouple. Thermopile is huge number of thermocouples set side by side and connected in sequence to make a wheel. In order that all the hot junctions, which are blackened to raise the energy absorbing capability, drop within a target area.
Wheel Type Thermopile
The new form of pyrometers is Pyroelectric which detects the thermal radiations. The construction material is frequently ceramics are materials whose molecules have an everlasting electric dipole because of the position of the electrons in molecules. Pyroelectric material is placed between two electrodes at ambient temperature. The molecular dipoles are rigid throughout the structure. While the temperature of the radiant object is amplified. And the temperature of the pyrolectric material increases above the is curie temperature and an electric potential is apply. The molecules of the ceramic will align themselves and an electric field will be produced in the ceramic.
Photo-electric pyrometers are used for in case the radiations of the measure objects are shorter wavelength at high temperature. Photo-electric pyrometers also very similar in construction to radiation pyrometers and are consequently confidential as its type. Using of photodiode as the detector rather than thermopile is the one of the major difference in construction. A photodiode is regularly a semiconductor diode.
Optical radiation thermometers are a uncomplicated in construction. Optical radiation thermometers are accurate for temperature measurement more than 600 oC to 3000 oC. But they still need the eye and the decision making of the operator. Therefore they are not a suitable device for recording or control purposes. But nonetheless, they are very effectual for point measurements and for calibration of total radiation thermometers. To use the instrument the point where the temperature is required to be known is viewed through the pyrometer.
The Electrocardiography (ECG) is a test used to measure the electrical activity of the heart. An ECG can be used to measure the rate of heartbeats, the position of the chambers, the presence of any damage to the heart and the effects of drugs and devices used to regulate the heart. This procedure is very useful for monitoring people with heart disease or to provide diagnosis when someone has chest pains or palpitations. Electrocardiography (ECG) instruments should design with some important thesis as the instrument should have capability to sense low amplitude signals should be in the range of 0.05 - 10mV. Other than that the instrument also suggested to have a high common-mode rejection ratio (CMRR) on the preamplifier stage. And even the frequency response should has a band width from 0.1Hz to 150Hz.
Block diagram of ECG
ECG measurement machines are different and sensitivity from the industrial measurement machines. This has been proving because the ECG signals are very small signal voltage, a modest frequency range and significant interference and noise.
ECG instruments are very good with:
1) Suppressing the interferences
2) Converting the biopotential into electric signal
3) Processing the ECG signal
4) Amplifying the small electric signal
What (Electrically) is being measured??
The measuring can be different with being different type conditions. Usually the some ECG will be recorded when the patient remain resting. But in some case as, some patients who having coronary heart disease symptoms, ECG will be taken while the doing exercise bike or treadmill. The electric waves in the heart are recorded in mill volts by the ECG. The waves are recorded by electrodes positioned on certain parts of the body. Each electrode controls an ink needle that writes on a grid paper. The higher the intensity of the electric wave, the higher up the needle will move on the paper. The paper moves at a certain speed beneath the needle, resulting in an ink curve.
How is electric signal capture??
Electrocardiography (ECG) is the getting hold of of electrical activity of the heart captured by an external electrode attached to the skin. Each of the cell membranes that form the outer covering of the heart cell has a linked charge. And it's depolarized during every heart beat. The ECG signal produced amplitude voltage in the presence of neither noise nor offsets. The common electrode used in ECG systems is AG/AGCl (silver or silver chloride) and has its maximum voltage of 300mV. The amplitude of the power line noise could be very high and needs to be filtered. The sensor of ECG records the pathway of electrical impulses through the heart muscle, and can be recorded on resting and ambulatory subjects, or during exercise to provide information on the heart's response to physical exertion.
Complete circuit of Block diagram
Vout = R3 (V2-V1) When Vout = 0,
0 = R3 (V2 - 1)
V2 = 1 When Vout = 10,
Vout = R3 (V2 - V1)
10 = R3(5 - 1)
10 = 4R3
10R1=4R3 Let R1= 10Kâ„¦
10 - 10K= 4R3
R3 = 25Kâ„¦
R3 = R4 = 25Kâ„¦
R1 = 10
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Voltage to frequency
The family of voltage-to-frequency converters ideally suitable for in simple low-cost-circuits for analog-to-digital conversion, precision frequency-to-voltage conversion, long-term integration, linear frequency modulation or demodulation, and many more. The output when used a voltage-to frequency converter is a pulse train at a frequency precisely proportional to the applied input voltage. Consequently, it provides all the inherent advantages of the voltage-to-frequency converter techniques, and easy to apply in all standard voltage-to-frequency converter application.
Frequency and Voltage
The tachometer uses a charge pump technique and offer frequency repetition for low wrinkle, full input protection in two versions and output swing to ground for a zero frequency input.
The amplitude is fully well-matched with the tachometer and has a floating transistor as its output. This characteristic allows either a ground or supply referred load up to 50mA. This version is well suited for single speed or frequency switching or fully buffered frequency to voltage conversion application.
An orifice plate is a device used for measuring the volumetric flow rate. Orifice plate is still being the most flowmeter which using by worldwide till today. Orifice plate are cheap and more benefits than other flowmeters. Particularly in huge size projects and it's worked well over many years.
The Orifice plate will be installed in pipeline and creates pressure when the fluid flows on it. The difference of the pressure will be detected or measured by a pressure transmitter. It will convert the readings into signals and it will screen the display of the rate of flow. And one more advantage of orifice plates are manufactured and installed following these standards is that they do not necessitate calibration. So the plates are cheap enough for larger pipe line sizes.
The Venturi meter consists of two conical pipes. Throat is named to the minimum cross section diameter. Venturi meter is discovered to control the energy losses due to flow separation. The Venturi meter produces the flow obstruction which will lead to local loss that is proportional to the flow discharge.
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The Venturi meter measure the losses produced through the meter by the pressure taps are located upstream and downstream of the venturi meter. But there is a disadvantage about Venturi meter. It does all about cost u spend for it. It's too expensive when it's used for large lines sizes.
Nozzles are commonly utilized in jet engines, rockets, spacecraft, and even garden hoses. A nozzle device that increases the velocity of a fluid at expense of pressure. The cross sectional area of a nozzle decreases in the flow direction for subsonic flows and supersonic flows. The rate of heat transfer between the fluid flowing through a nozzle and the surroundings is usually very small since the fluid has high velocities.
Nozzles are shaped so that they cause large changes in fluid velocities and thus kinetic energies. One disadvantage in the convergent-divergent nozzle as a shock wave can take place in the nozzle. A nozzle is a device that converts pressure energy to kinetic energy (increasing fluid velocity on the account of static pressure). For a convergent nozzle there is no disadvantage as it can raise the fluid velocity only for the sonic speed.
Pitot tube is used for measuring the stagnation within a channel, pipe or duct flow. Pitot tube is made in symmetrical body such as cylinder, cone, or hemisphere with drilled by the side of its central axis. If this is associated with its central axis in the direction of the flow the fluid will accelerate around the upstream face with less energy losses, and a stagnation point incline at the piezometric opening.
Flow measurement using (a) Pitot tube, and (b) Pitot-static tube.
Pitot tubes on aircraft commonly have heating elements called Pitot heat to prevent the tube from becoming clogged with ice.