Date post: | 24-May-2015 |
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Technology |
Upload: | benjamin-kyalo |
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Turndown Ratio Turndown Ratio of a Flow meterof a Flow meter
Why is it an important consideration when selecting a flow meter?
Turndown ratio – Flow meters
• Turndown ratio is a flow measurement term that indicates the range of specific flow meter is able to measure with acceptable accuracy.
• Turndown ratio can be expressed as;• TR = Q (max) / Q (min)
• Where TR = Turndown Ratio• Q (max) = Maximum Flow• Q (min) = Minimum Flow
Turndown ratio – Flow meters
• Example #1;
• If a gas to be measured varies between 100000m3/day and 1000000m3/day
• This specific application has a TR = 10:1
• The flow meter required should have a TR of at least 10:1
Turndown ratio – Flow meters
• If the flow meter had a maximum flow of 2000000m3/day then the required turndown ratio (TR) would be 20:1
• Example #2;
• Consider a 12’’ ruler graduated to a quarter of an inch.Since the smallest distance that could be measured is ¼’’
Turndown ratio – Flow meters
• The turndown ratio is
• 12’’/ 0.25’’ = 48 i.e, (48:1)
• If the same ruler all the graduated lines below 2’’ are smudged, then in this case the turndown ratio would now be
• 12’’ / 2’’ = 6 (6:1)
Turndown ratio – Flow meters
• Note;
• Turndown Ratio is one of a number of considerations when choosing or sourcing for a flow meter for your application
• TR of a flow meter is mostly affected by the devices signal-to-noise ratio (S/N Ratio) which results from the fluid dynamics of the technology and the type of sensor employed.
THANK YOU !!!
Presentation prepared by ;
Benjamin Kyalo
Technical Sales Engineer
+254735211022
www.google.com/+BenjaminKyalo
Nairobi, Kenya