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Join Date: Jun 2011
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# Input Range Calculations

06/08/2011 9:28 PM

If 0% of input range, square rooted out wil be 0%

If 25%of input range, square rooted out wil be 50% 12mA

If 50% input range, square rooted out wil be 70.7% 15.31mA

If 75% input range, square rooted out wil be 86.6% 17.8 mA

If 100% input range, square rooted out wil be 100% 20mA

Can someone explain how these calculations are made?

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Guru

Join Date: May 2009
Location: Richland, WA, USA
Posts: 20969
#1

### Re: Input Range Calculations

06/08/2011 10:26 PM

This sounds like a differential pressure flow meter. The flow is proportional to the square root of the pressure difference.

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#2

### Re: Input Range Calculations

06/08/2011 10:40 PM

2
Guru

Join Date: May 2009
Location: Richland, WA, USA
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#3

### Re: Input Range Calculations

06/09/2011 2:08 AM

Here is a sample correlation table for DP (differential pressure) of 0-60 with Q (flow) of 0-200.

main = output of DP transducer (input to further processing)
f = fraction of DP range
√f = converted fraction
maout = milliamp signal to indicate flow
Q = calculated flow

DP--main---f------√f---maout--Q
00---04--0.00--0.000--04.0--0
15---08--0.25--0.500--12.0--100
30---12--0.50--0.707--15.3--141
45---16--0.75--0.866--17.8--173
60---20--1.00--1.000--20.0--200

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#4

### Re: Input Range Calculations

06/09/2011 12:04 PM

thank you

Off Topic (Score 5)