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Creating bridge scale in labview -No calibration certificate with pressure sensor

Hello everyone,

 

I watched a Laview video online on how to measure pressure transducer  and applied the steps to my laboratory work ( https://www.youtube.com/watch?v=spTHTfjVlo8 ) but I couldn't go further when  I got to the section of creating a bridge scale for the pressure sensor model I bought from Measurement Specialties   (EPX-N02-1B-/Z2/L1M/25M) because the calibration certificate did not come with the device.

I proceeded to run the test but the pressure value I got was way beyond the capacity of the device (1 bar).

 

My question is; is there a way to sensibly adjust the values of the physical and electrical units without having the calibration certificate of the device?

 

Thanks in advance for your response.

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Message 1 of 5
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Hi Wapz,

 

My name is Mitchell Goon, from National Instruments Technical Support.

 

You will be able to download a detailed calibration certificate for your device from the NI website. You can refer to the link below for more information on how to obtain the Calibration Certificate:

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z000000P97MSAS&l=en-US

 

With regards to your query, you will need to have external signal conditioning before acquiring any data from the pressure transducer. These may include:

  • Bridge completion
  • Excitation
  • Remote sensing
  • Amplification
  • Filtering
  • Offset
  • Shunt Calibration

 

Connecting the pressure transducer directly to the DAQ device may yield unexpected results. You may wish to refer to the following links if you need more information of acquiring pressure with a DAQ device:

https://www.ni.com/en/shop/data-acquisition/sensor-fundamentals/measuring-pressure-with-bridge-based...

 

Additionally you may wish to refer to this tutorial on how to setup your DAQ device for pressure measurements:

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA03q000000x1jjCAA&l=en-US

 

I hope that this information will be useful for you. If you require any further assistance, please do not hesitate to contact us and we would be more than happy to assist you.

 

Kind Regards,

 

Mitchell Goon

National Instruments

Applications Engineering

www.ni.com/support

Message 2 of 5
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Hi Mitchell, thanks for your response, and can you please help me with the Two-point linear bridge scale for the attached calibration certificate of my sensor.

 

What will be the first and second values of both the physical and the electrical units? Would appreciate your response. Thanks

 

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Hi Wapz,

 

For the electrical values, the first and second values are the minimum and maximum values of the scale, which in this case refer to the sensitivity of the pressure transducer, as far as i understand. You should be able to get by calculation of the values from your calibration certificate. In this case the calculation should be:

 

Sensitivity (mV/V) = Full scale output (FSO, mV)/Excitation Voltage(V)

 

As for the physical values, the minimum and maximum values will be defined by the range of the pressure given in the calibration certificate.

 

You may wish to refer to refer to this forum post, which has a similar query to yours, which might be helpful for you:

http://forums.ni.com/t5/LabVIEW/DAQmx-AI-Bridge-Measurements-First-and-Second-Electrical-and/td-p/30...

 

I hope this information is helpful to you, do update me if this resolves your query.

 

Kind Regards,

 

Mitchell Lewis

National Instruments

Applications Engineering

www.ni.com/support

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Message 4 of 5
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Thanks Mitchell, so so helpful. Appreciate your time.

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