Hey,
I am new to the arduino world and am trying to use an arduino to measure the water pressure in a pipe.
The pressure should be around 0-20.000 Pa.
I have been looking for a sensor, however I could not find any good / reliable information..
Do you have an idea for a fitting sensor?
Thank you so much! 
20.0Pa is nothing, that's 2mm of water head
Do you mean 20kPa? Perhaps you searched for the wrong value - try "20kPa" or "200 mbar" in your
searches.
[ In English '.' is the decimal point, ',' is the thousands separator, this can be a source of confusion as
some countries use them the opposite. ]
Right - I meant 20kPa!
But I still only find pressure sensor, which I think are not suitable for water / wet use.
I found this one, but I am not sure, whether I can use it in water..
https://www.conrad.de/de/nxp-semiconductors-drucksensor-1-st-mpx2200ap-0-kpa-bis-200-kpa-print-1182857.html?sc.ref=Product%20Details
Would this work?
dschetel:
Right - I meant 20kPa!
But I still only find pressure sensor, which I think are not suitable for water / wet use.I found this one, but I am not sure, whether I can use it in water..
https://www.conrad.de/de/nxp-semiconductors-drucksensor-1-st-mpx2200ap-0-kpa-bis-200-kpa-print-1182857.html?sc.ref=Product%20Details
From the datasheet:
The MPX2200 series pressure sensor operating
characteristics and internal reliability and qualification tests
are based on use of dry air as the pressure media. Media
other than dry air may have adverse effects on sensor
performance and long term reliability. Contact the factory for
information regarding media compatibility in your application
outsider:
Would this work?
https://www.nxp.com/docs/en/data-sheet/MPX5050.pdf
Same disclaimer about dry air in that datasheet.
If the sensor isn't in a stainless steel or brass housing, I'd immediately doubt its anything but a dry air pressure
sensor.
Google “ pressure transducer for water “. - they are out there, but as you need stainless steel diaphragm , not so cheap.
I am a mechanical engineer that designs digital faucets, valves, controllers, etc,. and I still have yet to find a sensor that is as robust and easy to program as these cheap Autex analog pressure transducers. https://www.amazon.com/d/Automotive-Transmissions-Parts/Eyourlife-Universal-Pressure-Transducer-Solenoid/B00RCPDUTY/ref=sr_1_5?ie=UTF8&qid=1543406967&sr=8-5&keywords=autex+pressure
Autex are the best Ive found for the 20 dollar price range. Positive 5v, Grond, and analog voltage and a quick calibration and you are good to go.