pressure transmitters

Temperature range and temperature limits - they are not the same thing!

The parameters that define pressure sensors include temperature range and temperature limits. When hearing these types of terms, most of us will respond that we are dealing with the same parameter. However, is the instinctive answer the right one? Do the two terms express the same thing or should we differentiate between them? Below you will find the most important information defining the key standard that defines the differences between these terms.

Temperature range and temperature limits – what characterise these concepts

If we wish to examine the subject, it is worth starting from the beginning, i.e. the characteristics of these two terms. A linguistic analysis of the terms reveals that the term temperature range refers to the temperature range specified by the manufacturer of the equipment. On the other hand, the concept of temperature limits defines upper and lower temperature values, defining them in a precise way. Ultimately, both concepts are bounded by an upper and lower value, whereas when analysed linguistically, they can be distinguished as follows:

  • the temperature range is defined by the upper and lower limits and includes everything in between,
  • the temperature limits define the two values, upper and lower, within which the device can function.

Why do we distinguish between temperature ranges and limits?

The considerations above focus on the linguistic sphere and, from the users' point of view, are not relevant. The distinction stems from IEC 61987, the relevance of which will be discussed below and will draw attention to the aspects that make it possible to differentiate between temperature range and temperature limit values.

Importance of IEC 61987 in distinguishing between range and limit values

Moving on to IEC 61987 itself, it should be described as relevant to pressure sensors, as it defines the properties of fluid sensors. These in turn include pressure sensors. In this standard, the concepts of range and limit values are distinguished as follows:

the temperature range defines the range within which the specifications of pressure sensors should apply with regard to accuracy. The manufacturer gives guarantees that within the specified temperature range the device will give a reliable result, the limit values define the minimum and maximum temperature between which the equipment can be safely operated, without the specification being relevant. The manufacturer allows the equipment to be used safely at certain temperatures, but does not guarantee that the measurement results obtained will be reliable.

For whom is the distinction between temperature range and temperature limits relevant?

The term indicated by the aforementioned standard provides an answer as to why the two concepts are differentiated. It is important from the point of view of the user of these devices. And it is for users of the equipment, who expect accurate measurements, that this type of distinction will be important. The temperature range, then, is to determine at what temperature the pressure sensor will deliver results that are reliable and within its specification. Temperature limits, on the other hand, define at what minimum and maximum temperature the device can function without fear of damage.

The two terms can therefore define two different ranges, with the limit values providing the user with information on what temperature the equipment will operate at without fear of damage, but not necessarily the accuracy of the measurements taken. The temperature range must be taken into account when taking measurements, as it determines when the equipment is operating in such a way that a reliable measurement can be obtained.

Summary - do the technical differences matter to the ordinary user?

So it seems that what initially sounded surprising at the end turns out to be justified and a distinction should be made between the two concepts. The scope and limits will not always differ, but the technical distinction between the concepts should be taken into account. It should be borne in mind that there are pressure sensors where the two terms define the upper and lower temperature limits differently, and a technical distinction between the two terms will help to understand why this is the case. At the same time, one may wonder whether the two terms should take a different form so that their distinction can be made easier, also from the point of view of those who do not use the equipment and are not familiar with the standards. This is, however, a question to be answered by linguists.