Real-time sensor data is enabling factories to better understand their own processes and keep them running. And putting that data into the IIoT also helps optimize how raw materials are ordered, handled and consumed. Knowing what to reorder and when can keep continuous processes at high capacity. Smart manufacturing is changing the way we make, package and distribute just about everything. While the Industrial IoT is dependent on connectivity, fundamentally it’s harnessing raw data and turning that into operational intelligence, which means sensors are key to the entire process. While there are many types of sensor at play here, the pressure sensor is probably the most diverse and widely deployed type of sensor in the IIoT.
- Monitoring process flows
Differential pressure sensors are used extensively in process flows where a fluid needs to pass through some form of barrier, such as a filter. Under normal conditions the pressure difference between the upstream (often called the line or influent pressure) and the downstream (effluent) pressure should be nil or minimal. As the filter becomes blocked with contaminants, the downstream pressure will decrease, which causes the difference measured to increase. The sensor’s output can be calibrated to show the maximum permissible pressure difference at full scale.
- Measuring safe levels in liquid tanks
Submersible pressure sensors that are certified for use in intrinsically safe areas can be used to measure liquid pressures of up to 30 PSI with either a voltage or current (4-20mA) output. Positioning a submersible pressure sensor at the bottom of a tank would provide an accurate reading of the contents of the tank, thereby alerting workers or the process control system when the level in the tank falls below an allowable lower limit.
- Managing control loops
As well as being used to monitor processes, pressure sensors are often instrumental in the control loop. This is particularly relevant in the use of hydraulics, where pressurized fluids are used to apply effort in presses or lifts for example. The sensors are often small, particularly those based on MEMS technology. They can measure less than 2mm on each side yet be capable of measuring absolute pressures in the region of 20 Bar or more. This makes them suitable in a range of applications, including medical and automotive.