Does the lower range limit of all instruments start at 0? Is this statement correct?

First, we need to define what 0 is, and then discuss whether everything starts from zero. For example, if atmospheric pressure is defined as zero, the lower limit for pressure measurement will be below zero ； If absolute pressure is defined as zero, the lower limit of the range starts from zero.

Both temperature and pressure can have negative values; they don’t have to start from zero

So can my thermometer still measure temperatures below zero, and can a vacuum gauge detect vacuum?

Not all of them, but a large portion start from zero; there are those above zero as well as those below zero.

The last edit to this post was made by qqgd on 2024-9-11 at 09:15. The range of a gauge actually refers to the starting point of the gauge signal to the set ending point of that signal; it may differ from the actual zero point of the physical quantity being measured. Because for many smart meters, the starting point of their output signal can be a specified measurement value above the zero point on the scale of the physical quantity being measured, or it can even be set within any reasonable range. Additionally, the signal of the instrument can also be set to change in the reverse direction. From a mathematical perspective, the setting of the instrument’s range involves the specification of the coordinates for the physical quantity being measured, as well as their translation and/or transformation (including corresponding scaling), and it need not be linear; it can even be expressed in terms of discrete values.