Pressure measurement is an integral part of any industry, mainly in the control and instrumentation industries. The selection of pressure sensors are dependent on various factors like accuracy, performance, type of signals, and operating medium. The measuring range of the pressure sensors is a pretty important factor to be considered before choosing one.
Most applications do not need sensors that cover a very wide range of pressure. But, real time systems behave in completely unexpected ways, and all possible outcomes have to be taken into consideration before choosing the right measurement range.
Three major factors must to be taken into account:
- Normal operating pressure of a system: Consider the highest pressure and lowest pressure at which the pressure has to be measured in that particular system. The lowest pressure measured could be 0 psi, or it could be negative also. The optimal pressure range of the system is the first factor to be considered. The maximum pressure to be measured by the sensor must not exceed the maximum range of the sensor. If this happens, it could lead to product damage and potential failure of the system.
- Pressure changes during operation: After the optimal measuring range is decided, any potential changes in the pressure due to system dynamics are to be considered. System dynamics could mean starting or stopping of pumps and motors, or opening and closing of valves. Changes in operating temperatures could also affect the pressure range of any system.
- Drastic changes in pressure: Many industrial systems might experience a sudden spike in pressure called “over pressure”, or a sudden fall in pressure. A sudden increase of pressure causes damage to the sensor; if the sensor is meant only for a specified range.
Pressure sensor manufacturers must specify the overpressure ratings, in addition to the optimal measuring range of the sensor. All datasheets generally have three values with regard to pressure range. They are rated operating pressure, safe operating pressure, and overpressure. Different manufacturers may use different terms to specify these three values.
Selecting a sensor with a very large measuring range to accommodate pressure spikes; is also detrimental to accuracy. Care has to be taken, so that accuracy and resolution are not compromised in the selection process.