In [[flow measurement]], '''flow meter error''' is typically reported by a percentage indicating [[non-linearity]] of the device. This can be expressed as either a +/- percentage based on either the full range capacity of the device or as a percentage of the actual indicated flow.<ref>{{cite web|url=http://www.maxmachinery.com/faqs#n104|title=Frequently Asked Questions - Max Machinery|website=www.maxmachinery.com}}</ref> In practice the flow meter error is a combination of [[repeatability]], [[accuracy]] and the [[uncertainty]] of the reference [[calibration]].<ref>http://www.flowmeters.co.uk/liquid-flow-meter-performance-specification-glossary/</ref>
[[File:Error chart % of full scale vs % of reading.jpg|framed|right|Error chart % of full scale vs % of reading]]
==References==
== Accuracy of full scale ==
If a meter’s accuracy is based on a percentage of its full reading capability, the error is a fixed value. For example; an error of 0.5% of full scale, in a 100-gallon per minute (gpm) device is +/- 0.5 gpm. This is the uncertainty all of the time, so as you move away from the full scale capability, the 0.5 gpm error becomes a much larger percentage. At 50 gpm, you are risking a 1% error. At 10 gpm you have a potential 5% error.
the flow meters can be affected by the air pressure from the surrounding so it needs to be carefully be observed
==Accuracy of reading==
If the device has an error expressed as a percentage of the actual flow, then a 0.5% error of 10 gpm is only +/-0.05 gpm; a 10 times better result.<ref>http://www.maxmachinery.com/frequently-asked-questions</ref>
