Temperature, air pressure, humidity and many other conditions can affect the measuring instrument or the item being measured. For example, do not place a thermometer on a wall near an air conditioning outlet to find the temperature at a workbench. The measurements taken must be properly representative of the process being assessed. (Gross mistakes are a different matter and are not to be accounted for as uncertainties). The use of an instrument such as a stopwatch depends on the reaction time of the operator. One person may be better than another at the delicate work of setting up a measurement, or at reading fine detail by eye. Some measurements depend upon the skill and judgment of the operator. For example, measuring the weight of a lively animal presents particular difficulties in getting the subject to cooperate.Ĭalibration of the instrument has an uncertainty which is then built into the uncertainty of the measurements made. The measurement itself may be difficult to make. The item being measured may not be stable, for example measuring the size of an ice cube in a warm room. Instruments can suffer from errors including bias, changes due to ageing, wear, or other forms of drift, poor readability, and noise. Sulphur Recovery Burner Technology (SUREburner)Īs real measurements can never be made under perfect conditions, errors and uncertainties can come from: Source Refrigeration & Air Conditioning Processes Official BOC UK Online | Industrial Gases | Products & Solutions | BOConline UK

Measurement of uncertainty