Fundamental Things About How Pressure Sensors Work

As the most used systems for pressure measurement, the pressure sensors are good for gases and liquids. The devices can be seen in action when the fluid reaches the containing limit and pushes on the elements of force detection from the equipment. This is the moment when an electrical signal is created and sent to an interpreter. This is the functioning principle on which every sensor is based.

The force parameter is not the only one measured; there are also secondary measurements like the substance amount or the flow of the liquid/gas. These devices can measure a lot of things. The reading can be either static or dynamic.

Since the steam age, these equipments were very much used and demanded. And were used until now, when they have the same popularity. They can be categorized through the functioning principles in three types: strain gage, piezoelectric and variable capacitance.

These equipments can be found under various types and designs. They can be of high performance or of lower performance but cheap. They can be different because of the measurement ranges or temperature ranges. As an example of high performance pressure sensor, the dynamic devices which detect fast modifications in speed and pressure are the ones. They are built from quartz crystals (piezoelectric).

Strain gage devices are constructed from 2 parts: the diaphragm and the strain gauge. When the force created by the fluid increases, the diaphragm detects the modification and it sends a signal to the strain gauge. Now the strain gauge will resist the force. Then the resistance force generated will be measured by a Data Acquisition System or DAQ.

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. Like the accelerometer, 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.

Being made of quartz crystals, the piezoelectric sensors use the properties which are owned by these crystals from nature. They have this feature that allows them to make an electrical charge when they detect a force increase. The signal created must be amplified with the proper circuitry. They are not as resistant as other materials to vibration exposure or to any type of shock.

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.

The popularity of pressure sensors is very high in these times. Their use has extended in various domains like, for instance in the food industry. No matter of what type they are, their main use is for measuring the forces created by various fluids and their speed, their level in containers etc.