PRESSURE SENSOR TRANSMITTER
A pressure sensor is an instrument consisting of a pressure-sensitive element to monitoring the actual pressure and converts it into an electric signal where the amount can be for instance temperature, length, force, and pressure. Then a data analyzer reads that data and shows it on a display of a control system.
TYPES OF PRESSURE SENSORS
The most widely used pressure sensors in modern manufacturing industries are piezoresistive pressure sensors. And the most expensive unit in the sensor is the piezoresistive diaphragm – mostly made of Silicon Crystals and Certain Ceramics. Piezoelectric crystals generate an electric charge when exposed to mechanical stress, which is proportional to the force/pressure applied. A signal conditioner converts the charge signal into a voltage signal. Ceramics are used to measure the pressure of strong corrosive gas or liquid.
Piezoresistive pressure sensors are ideal to measure dynamic pressures. Small pressure pulsations (Such as Compressors Aerodynamic) and quasi-static pressures, Piezoresistive pressure sensors are available to measure in a short time in very high or low temperatures.
STRAIN PRESSURE SENSORS. THE MAIN UNIT IS THIN TWISTABLE POLYMER FILMS(FOIL).
Pressure signals generated from the strain foil are too weak and need a Wheatstone bridge to amplify and optimize the measuring data. The strain type foil is the lowest cost material in many manufacturing industries. The Wheatstone bridge has 4 lines and each of them has a result and all results will be calculated to precise the measuring data.
Strain pressure measurement not available for high pressures happens in high frequency in a short time. And the measurement data are easily affected by temperature. Thus Strain sensors are not good options for modern industries such as airplanes, ships, cars, and mining industries...
Capacitive pressure sensors use a pressure cavity and foil (diaphragm) to produce a variable capacitor. The foil has a shape transform when pressure is applied and capacitance decreases accordingly. The capacitor is a sort of battery that supplies electrical power according to pressure values. Thus this change in capacity can be measured electrically and transmit into signals. These sensors are limited to low pressures. Capacitive pressure sensors are economic in price but with higher electricity consumption than Piezoresistive pressure sensors. Capacitive pressure sensors are used in bed monitoring systems, intelligent sneakers, Door pressure switches.
PRESSURE SENSORS BY MEASUREMENTS
Absolute Pressure Sensor
Absolute pressure is the sum of gauge pressure and ambient atmosphere pressure, It measures the input pressure from a medium with reference to a vacuum zero pressure. Absolute pressure is the real pressure in closed systems or sealed containers in the atmosphere at a certain altitude. Absolute pressure is the main reference of food and beverage industries, Material industries, Transportation industries. Absolute pressure sensors are typically used in research and scientific applications.
Differential Pressure Transducer
Differential pressure measurement is based on two independent but relatively existing pressures. Pressure transducers with a diaphragm which one side measures to medium one and the other side measure another medium. The pressures are referred as to high pressure and low pressure. The application of Differential pressure transducers are very vast. Such as water processing industries, sewage treatment, fluid boilers, HVAC applications
Gauge Pressure Sensors
Gauge pressure is the pressure between absolute pressure (total pressure) and atmospheric pressure. (Gauge pressure= absolute pressure- atmospheric pressure), The gauge pressure measurement is used on a car tire, natural gas transportation, hydrogen cylinder, fire extinguisher-related products. Also used in livestock feeding applications.
