Thermal conductivity barometer
In real gases, as the density of the gas increases with increasing pressure, the heat conduction capacity increases. For this reason, this property of gases is used to measure pressure. In these barometers, a filament system is heated by an electric current, then the filament temperature is heated by a resistive thermometer (RTD) Resistance Temperature Detector This temperature is measured as the amount of heat loss of the filament to the surrounding gas environment (thermal conductivity of the gas Thermal conductivity in gas) It Depends. From this relation, the amount of pressure can be obtained. These thermometers are divided into two types, two-wire and one-wire. The two-wire type of this barometer uses one coil as a heater and the other wire near the heating filament to measure the temperature. These wires are mostly made of platinum
One type of wire of these barometers is known as Pirani barometer
Pirani gauge barometer
This type of sphygmomanometer was developed in 1906 by Marcelo Stefano Pirani Marcello Stefano PiraniWas invented. Pirani barometer is one of the most common thermal conductivity barometers that uses platinum, nickel or tungsten filament. Pirani sphygmomanometer is designed and built based on the dependence of the resistance of a heated wire on the temperature of that wire
In other words, this barometer consists of a platinum wire that is subjected to measured pressure, the wire is heated by an electric current and cooled by the surrounding gas. If the gas pressure decreases (with increasing vacuum value), the cooling effect decreases and therefore the equilibrium temperature of the wire increases, and as a result the resistance of the wire, which is a function of its temperature, changes by measuring the voltage across the two ends. The effect of passing the appropriate heating current is created, the pressure under measurement can be determined. This type of sphygmomanometer has a good accuracy in the range of 10 to 3-10 ns (vacuum range) and is usually used to measure vacuum.
Thermocouple pressure gauge
Thermocouple and thermistor barometers work similarly to the Pirani barometer, except that in these barometers, the pressure is measured directly based on the temperature change of the wire. The figure below is a schematic view of a thermocouple barometer
Rose Calibration Company in Melbourne, Australia with over ten years of experience provides all calibration, maintenance, and repair services throughout Australia. If you live in Sydney, Melbourne, Adelaide, Perth, Geelong, and Brisbane, you can receive your quote in less than two hours by fill-up the form via the “Booking” link.