Error

Error in a measurement is the difference between the true value and the value that is measured.

It can be broken down into:

  • Systematic Error: Constant and predictable errors that consistently cause measurements to be incorrect by a fixed amount.
  • Random Error: Errors that occur without a predictable pattern, varying in magnitude and direction.

Error = [Measured Value−True Value Error]

Range

Range is the span between the minimum and maximum limits within which an instrument can accurately measure. For example, a thermometer might have a range of -10°C to 50°C.

Rangeability

Rangeability or turndown ratio is the ratio of the maximum to minimum measurable values that an instrument can accurately measure within its specified performance limits. It is a critical factor for instruments that need to operate effectively at various levels within their range.

Rangeability = (Maximum Flow Rate / Minimum Flow Rate)