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Basic Tips on the Working Principles of Pressure Sensors

29 11:46:38

Basic Tips on the Working Principles of Pressure Sensors






     Pressure sensors are devices that are meant for measuring the pressure. The measuring applies to any liquid or gas. When the level of substance has reached a certain limit and has even passed over it, the device translates the force generated into an electric signal. This signal is interpreted by a computer and in this way the measurement is made.

Not only the direct force can be calculated, but also other parameters will be obtained indirectly. This involves the level of fluid in the container, the speed of flowing and others. Any type of information can be provided by these readers. The measurement can be static and dynamic.

The requirement for these devices dates from steam age. Many of the equipments that were invented then are still used in our time. There are three types of these devices: piezoelectric, variable capacitance and strain gage.

The sensors can be found in different shapes and designs; they can be classified after performance or price, after the range of measurement and the temperature range of use. There are some dynamic sensors that can measure rapid changes in speed or pressure, these ones have a high performance and are made of quartz.

The strain gage systems are made of two things: the strain gauge and the diaphragm. The diaphragm detects the changing in force when the level of the fluid grows. Then the strain gauge will oppose resistance for that force, and the resistance will be calculated by a DAQ module (Data Acquisition System).

When it comes to the devices that use variable capacitance, these are made of two metal plates. Actually it is one metal plate and a metal diaphragm. When the force changes, the distance between the plates changes as well and this indicates the difference in pressure. These devices are more stable than others but they do not function well in high temperature conditions. Also they are harder to assemble then the other types.

The piezoelectric devices are built from quartz crystals and they use the natural electric characteristics of these materials. When they are under physical stress, these crystals generate an electric shock. They require amplification of the signal. They are less resistant to physical shocks and high vibrations than the other devices.

The signal obtained from the sensors is usually small and it can be measured in mV (a thousand parts is one Volt). The range of Volts that is outputted from the device is related to the amount of physical force which generates the current. For instance, zero Volts mean zero force. In this point no electrical signal is sent to the interpreter. The maximum range limit can be, for instance 5V, case in which a pressure of 5 Bars is generated.

Pressure sensors are devices that are very common in our days. They are used in many industrial domains. For example, they have a good role in the food industry. Regardless of their type, they are good tools for measuring the force generated by different fluids. But they also measure the fluid speed, the level of a fluid inside a container or many other valuable details.