Natural gas measurement accuracy: error, tolerance and uncertainty

No measurement is perfectly absolute. To correctly evaluate a reading, one must know the error, tolerance, and uncertainty of the measurement system.

Error

It is the difference between the instrument reading and the actual or reference value.

Tolerance

It is the permissible limit within which the deviation is considered acceptable.

Uncertainty

It expresses the range within which the actual value is expected to lie with a specific confidence level.

Practical significance

In commercial metering or energy balancing, even a small systematic deviation can create a significant difference over long periods.