Pressure Sensing Instruments And Their Applications

A pressure sensor allows for the measurement of pressure, usually of liquids and gases. They can also be used to deduce other factors such as altitude, speed or water level. They are used in thousands of applications in everyday life and their design, performance and technology can vary greatly from one model to another. We will now take a look at just some of their numerous functions.

Altitude
This type of sensor is used in machines such as aircraft, satellites and weather balloons. They are able to measure changes in pressure relative to the altitude. However, due to variable factors such as temperature, errors need to be factored in. As a result, different types of pressure sensor may be more or less accurate.

Level
These sensors usually measure the level of a fluid and consequently can be used to determine the depth of a submerged body. In most cases, it can be assumed that fluid level is directly proportional to pressure, therefore it is easier to achieve better accuracy with this kind of pressure sensor.

pressure sensor

Flow
To measure the flow of a fluid through a tube, a venturi tube is used, which reduces the flow of the fluid by constricting the width of the tube. The flow rate can be deduced as the pressure difference is directly proportional to the flow rate through the venture tube. As this difference is small, a low pressure sensor should be used.

Leaks
Pressure sensors can be used to determine whether there is a leak in a system. There are two methods for this. One is to compare the current pressure in the system with the suspected leak to that of the known pressure without the leak. The other is to measure the change in pressure over time   if it decreases, it is likely that there may be a leak of some description.

Types of sensors
Depending on its intended application, a different type of pressure sensor will be used. A gauge pressure sensor gives a pressure reading relative to the pressure of the atmosphere   for example, a device you would use to check tyre pressure. On the other hand, an absolute pressure sensor is relative to perfect vacuum (i.e. no air). Other types of sensor are vacuum, differential and sealed pressure sensor, which measure low pressure, the difference between two pressures and pressure relative to a fixed pressure (rather than atmospheric pressure like a gauge pressure sensor), respectively.

Evelyn Brook is an aeronautical engineer and specialises in fitting pressure sensors to civil and military aircraft.

Photo source: http://www.flickr.com/photos/noii/8321715666/

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