Python code for finding the pressure differential using a Honeywell pressure sensor

Automation and Control Sensors Transducers
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Hi, I’m working with the Pressure Sensor 1PSI (6.89kPa) Differential Male - 0.19" (4.8mm) Tube, Dual 0 mV ~ 18 mV (12V) 6-SIP. The part number is 480-6686-ND. I’m pairing it with a Raspberry Pi Model 3 and was wondering if I could have any help with the python code. I’m connecting two different bits of tubing to each male connector and was wondering if anyone has used it to continuously display the pressure differential.

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How are you connecting the sensor to the Raspberry Pi? The sensor has an analog output and the Pi doesn’t have an ADC. If you need one this may work for you 1528-1461-ND. There is a good tutorial on Adafruit for this ADC.

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With a sensor full scale output span of only 18mV, you’ll likely also need some amplification between the sensor and ADC.

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I’m currently using the PCF8591 ADC/DAC Module

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Since I’m rather new to this, what would be the best way to do so?

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One would typically use an op amp in a non-inverting configuration for such a task. Your search engine of choice should come up with lots of resources on the topic if asked nicely.

That said, the PCF8591 only provides 8-bit resolution and uses its supply voltage as a reference, which is likely to introduce errors. I’d suggest using a similar sensor such as the 5525DSO-DB001DS with an integral ADC. That device offers 24-bit resolution, lower cost, better availability, and potential to connect directly to a Pi with no additional boards needed.

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The best way depends on dozens of factors revolving around price, calibration labor & tools, resolution, accuracy, ambient environmental conditions etc.

Basically this is a sensor style designed in the late 1970s, was state of the art last century, and is obsolete for most uses in this century. The amplification level required with a 3.3V reference for full scale resolution is 183X. That’s a bucket load of gain to get without excessive noise errors, time, and even room temperature drift errors.

I designed a circuit for a very similar absolute pressure sensor back in the early 90s. That circuit had to get maximum performance at minimum production cost and would cost over $10K to design in 2021 dollars. Of course if the dozens of application specific requirements are low enough it could be just a few thousand dollars to design.

Best bet is as @rick_1976 suggests, get a sensor with a digital output.