Peter Drucker is a well known management consultant and author whose work continues to be used by modern companies. One of his more famous quotes is, “If you can’t measure it, you can’t improve it”. A corollary to this “you can’t control what you can’t measure”. This is certainly true within manufacturing and process control. When you want to maintain a process variable you must first measure it before you can control it. As a result, it is critical to consider the sensors as part of an industrial transformation.
What are we solving?
I have written about how it is important to consider the business challenge to be solved before beginning a transformation effort. In the process of solving the problem you may need to add sensors to capture addition process or facility data. Unfortunately, much more consideration is given to other parts of the effort (software and analytics platforms) than the sensors. However, to reinforce the message above, you must be able to measure it before you can analyze it. Sensor selection is equally important.
What are we measuring?
Selecting a sensor starts with the knowing exactly what it is you want to measure. While this seems somewhat obvious, getting the right sensor is a critical first step. Sensors can provide direct measurements or inferred measurements. For example a pressure sensor can measure pressure (direct) or it can measure flow (inferred) through a pressure drop. Like any technology you must be able to support it within your organization. If you have mostly pressure measurements, using a pressure sensor for a flow application makes sense. Otherwise you will introduce another technology that needs to be supported, which is not always a good idea.
What kind of sensor?
Once you determine what you want to measure, you need to consider they type of sensor you want to have. If you need a basic measurement will little configuration a sensor is a great choice. However, if you want to have the ability to configure a scale, you should look at a transmitter. The fundamental difference is a sensor provides a defined output while a transmitter takes the sensor output and allows you to adjust the output (scalability, calibration, digital outputs, etc.).
What tier of sensor?
Within brands of sensors you need to determine the tier of the device. For the purposes of sensors, this generally addresses the accuracy and features. This is similar to trim levels on a car. Generally, the greater the accuracy and the mores features you want, the more the sensor will cost. Keep in mind you may never realize the benefit of a higher tier sensor if your system is not able to control at a finer level. If this is the case, a premium sensor should be selected based on other desired features.
What is the cost of installation?
Installation costs is also a consideration. A wired sensor will require you to install conduit and pull wires. If the value of the measurement does not justify the cost, you should consider a wireless sensor. Over the last decade, there have been significant advancements in wireless sensors. A current best practice is to use wired sensors to ensure safe operation of a process and wireless sensors for enhancing your measurement capabilities. There are a number of benefits that can be realized with wireless sensors, including reliability, safety, quality and diagnostic capability.
To be sure there are many more considerations that go into selecting a sensor. I have outlined just a few of them. The point is that when you begin on your industrial transformation journey, it is important to consider every component that goes into providing the data. Analytics software can realize some amazing results. Just don’t forget the sensors.