# Pressure transducer specs help needed!!!

Discussion in 'The Projects Forum' started by hamzasyyed, Dec 3, 2011.

1. ### hamzasyyed Thread Starter New Member

Dec 3, 2011
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0
hi everyone
i'm currently in the designing phase of a pressure decay leak detection system.
im having some trouble understanding which pressure transducer to use.
i was having a look over the internet at the different transducers available and their resolutions, the problem is that not many have the resolution listed on the specs sheet, is there some other way to calculate the resolution from other specs??? the other question is that how will i find the minimum voltage change that a transducer will produce?
as the transducer will be connected to Siemens S7 300 (12 bit built in ADC) PLC, i have already calculated the resolution of the PLC by dividing the voltage range by 2^12, now i want to compare the resolution of PLC and the transducer? but i cant do that if im not given the min voltage change caused by a certain pressure change(i am not aware of how to find the resolution of the transducer)
please any one help me

2. ### wayneh Expert

Sep 9, 2010
11,910
2,854
∆V for ∆P seems like a "must have" for a pressure transducer datasheet. Can you link to one we could read? Maybe it's just a terminology problem.

Dec 3, 2011
2
0
4. ### kubeek AAC Fanatic!

Sep 20, 2005
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The transducers are linear, not digital. Linear things don´t have resolution, only noise background limits what minimal difference you can measure.

5. ### wayneh Expert

Sep 9, 2010
11,910
2,854
As I understand those datasheets, these transducers produce a maximum output voltage (or current, for the 4-20mA sensor) at the top end of the pressure specification, and a proportionally lower voltage as the pressure drops. The top end voltage can vary with the input voltage, so for instance 100mV at 10v supply or 50mV with a 5v supply. So 1% of full scale will be 1 mV or less.