When I was designing industrial tsting and calibration systems the two main criteria were stability and ruggedness. Because of the types of testing the machines did, the readings only needed to be accurate at the points of interest, often at a single point. So the transducer had to hold calibration for that particular pressure point, and be veryy stable. Calibrations were normally done quarterly, at least that was the target, and by selecting the right sensors we would normally only need a very small correction on a yearly basis. So it was far cheaper to spend more on a stable transducer that wound up only needing to be checked on a yearly basis. That stability won my argument for purchasing the more expensive device. Mechanical durability and freedom from mechanical aging, (diaphram work hardening), and electronic stability, wound up being the two primary parameters in our selection process, because that was what mattered to our customers.
The customer may not always be right, but they are always the ones with the money.
For the most extreme situation I think that is the case, but for markets and applications that are large enough, they drive standard solutions even if those are ruggedized solutions. One other thing that has become important is that to have the flexibility and scale to create a particular solution, it is much more efficient to have a standard product platform that the sensor supplier then takes and implements a ruggedized solution on top of the standard product. Much faster and more efficient than developing the entire sensor from scratch. This is how we have positioned our standard product platforms at Honeywell to address individual customer needs for ruggedized sensors. - AJ Smith
That can be the case, Rob, and increases as the sensor becomes more specialized. When it comes to doing something completely custom there are often times development agreements and engineering costs involved beyond just the cost of the sensor as well. - AJ Smith
Rob, What I see is that environmental resilience is much like other performance factors in that the more stringent the requirement (in this case the more extreme the environmental factor(s) the fewer options there are to choose from. And in some cases for really extreme environments the design engineer may need to work with a supplier to develop a product that can meet their particular requirements. - AJ Smith
Nice article A.J. - I appreciated your very straightforward explanation of pressure sensor selection. I can also see how your criteria can be easily adapted to selecting any sensor by using your general principles coupled with sensor specific criteria. It's so important for the design engineer to understand all of the variables involved when making a selection!
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