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Home > Tips & Tools > Be smart

Be smart. Understand specs from various manufacturers

Our staff has been dealing with customers for many years understanding their language, their expectations and requirements when inquiring about pressure sensors. Along the road, we have realized that understanding specifications of pressure sensors is not as easy as it may sound, mainly because there is no universal language and sensor manufacturers use different language to spec their products. So we are trying here to review the different languages and help you be smarter when shopping around.

Accuracy

This is the most widely talked-about specs. This is also the most controversial as many suppliers have their own definition. And there's a good chance that you've already misunderstood it.

When talking to users, accuracy usually should include all possible errors for the customer's application. When using a device, the customer wants to know how accurately he will be able to measure his pressure. This is a logical approach.

Well yes, but according to the definition of the accuracy and according to manufacturers and suppliers, accuracy usually means the global error or total error band at a constant temperature (25C or 77F). So, the accuracy usually includes linearity, pressure hysteresis and pressure repeatability at 25C or 77F. And unless your application runs at a constant temperature or in a narrow temperature range, this value will not mean much to you.

Typical vs Maximal error

Most manufacturers and suppliers are using typical and maximal adjectives to describe their specifications. So make sure you understand what these terms mean.

Let's consider a sensor that is promoted with a 0.1%FS typ., 0.2%FS max. accuracy. What does this mean? This means that when producing an awful lot of sensors and running some statistics, around 80% of the sensors will have an accuracy within 0.1%FS and all the sensors (100%) will have an accuracy within 0.2%FS.

You will think: "Yes, but what if I just order a few pieces". Well, if you just order a few pieces of this previous sensor and if you're lucky, you'll get the 0.1%FS accuracy. But actually, there is a 80% chance that you get a 0.1%FS accurate device and a 20% chance that you get a degraded accuracy between 0.1%FS and 0.2%FS.

Finally, note that in most cases when the typ. or max. adjectives are not explicitly mentioned in literatures, the given value usually is a typical value. So make sure to ask if it's the case and if it is, ask about the maximal value as well.

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