# Accuracy of a flow measuring instrument

• rollingstein
In summary, the spec. sheet for the instrument states that its accuracy is 2% of full scale deflection (FSD). This means that when compared to a gold standard calibrating instrument at a flow of 500 Litres per hour, the absolute error can be up to 20 Litres. This results in an allowable error of 4% at 500 LPH nominal flow. It is important to consider both the absolute error and the relative error of ε% when measuring with this instrument. The accuracy can be improved by using calibration equipment to measure and correct for the error. The decision on whether the 4% allowable error is acceptable is ultimately up to the individual.

#### rollingstein

Gold Member
I have an instrument whose spec. sheet mentions Accuracy as 2% of FSD.

The scale runs from 0 to 1000 Litres per hour. Does this mean if I check the instrument versus a gold standard calibrating instrument at a flow of 500 Litres per hour (which is our typical flow) the absolute error can be as large as 2% of 1000? i.e. 20 Litres?

If so, then the allowable error at 500 LPH nominal flow becomes 4%.

Am I doing this right?

Yes, your measurement accuracy is 500±20 LPH. There is usually also a relative error of ε%, so you measure (1+0.01ε)500±20

If you have calibration equipment you can measure the error (with a certain accuracy) and correct for it (with a certain accuracy).

If the error is allowable or not is up to you, I have no idea where the 4% comes from.

## What is the accuracy of a flow measuring instrument?

The accuracy of a flow measuring instrument refers to how closely it can measure the volume or flow rate of a fluid compared to the actual value. It is usually expressed as a percentage, such as +/- 1% of the actual value.

## How is the accuracy of a flow measuring instrument determined?

The accuracy of a flow measuring instrument is determined through calibration, which involves comparing the instrument's measurements to a known standard. This process helps to identify any potential errors or discrepancies in the instrument's readings.

## What factors can affect the accuracy of a flow measuring instrument?

Several factors can affect the accuracy of a flow measuring instrument, including changes in fluid properties (such as temperature, pressure, or viscosity), mechanical wear and tear, and human error during calibration or operation.

## Why is accuracy important in flow measurement?

Accurate flow measurement is crucial for many applications, such as monitoring and controlling industrial processes, measuring fuel consumption in vehicles, and ensuring accurate dosing of medication in healthcare. Inaccurate measurements can lead to inefficiencies, errors, and potential safety hazards.

## Can the accuracy of a flow measuring instrument be improved?

Yes, the accuracy of a flow measuring instrument can be improved through regular calibration, proper maintenance and care, and using the instrument within its specified operating conditions. Upgrading to a more advanced and precise instrument can also improve accuracy.