Analog Water Pressure Sensor Range
Russel.Metlitzky 2025-12-20 06:43:34 649 Views3 Replies I purchased the Gravity: Analog Water Pressure Sensor recently and am setting it up with my Pico W. I'm confused on some documentation. The sticker on the sensor says it's output voltage is 0.5-4.5V and it's range is 0-1.6MPa. When looking on the DFRobot wiki page for this sensor, the specifications of the sensor shown on the page says it's range is 0-1.6MPA but the comments in the example code below that shows “Output Voltage: 0.5-4.5VDC (linearly corresponding to 0-1MPa)” The code then shows a correlation of 250 KPa to 1V. This came from a voltage range of 4V (4.5 minus 0.5) and a range of 1MPa which is 1,000kPa. So, 1000/4 = 250kPa per volt. BUT, if the range is really 1.6MPa then I should be using 400kPa per volt, correct? So, what is the range I should be using? 1MPa or 1.6MPa?
It is frustrating that there are such big inconsistencies and errors in the official documentation and code. What I have discovered is that the correct reading in Kpa is obtained by first scaling the ADC reading ie multiply the reading by ref voltage/2^N where N is the number of bits used by the ADC so for the typical 10 bit ADC it will be 1024, and the reference voltage is usually the 5volt supply but the latest Arduino uno Q board has a 14bit ADC and a 3.3v reference ! So check carefully first.
This scaled reading, minus the offset, must be multiplied by 400 to get Kpa - not 250 or 2500 as in the two code examples ! This corresponds to a pressure range from 0Mpa to 1.6Mpa with an output from 0.5vto 4.5v
In my case the offset was 0.48v and the output readings corresponded with an analogue pressure gauge up to 300kpa which as high a pressure as I have available.
Hope this helps.
Richard.Loch ear Sir,
With reference to the Gravity Water Pressure Sensor Purchase at last Month dated 23/12/2025 ( Invoice attached), but it is not working.
I have used it in a 1 litre water Bottle but it doesn't work. It doesn't show any change in value as the water level changes.
I am looking forward to your kind cooperation.
Kindly consider it as urgent.
Thanking you.
Regards
D Dutta.
DWAIPAYAN.DUTTA To add to my original post, does it seem odd that my zero voltage is 0.75V instead of something closer to 0.5V? And if that's correct, should my range now be 3.75V (4.5-0.75) instead of 4V and should I be using 1600kPa/3.75V for 426.67 kPa/V?
Russel.Metlitzky 
