I'm an Arduino noob and need some help putting together a data logging pressure transducer setup for monitoring levels in groundwater wells. I am a graduate student studying hydrogeology, and for my thesis I am evaluating the groundwater flow regimes on a farm field in Ohio through 15 shallow wells (maximum depth 8ft). I would like to make an Arduino centered data logger connected to a pressure transducer sensor that is submerged in the well. I found a similar build to what I want to do (minus the barometric sensor, temp sensor and wireless set up) that is linked below. I have done some research and found a couple pressure sensors I think I could use but I have many questions (links below). I'm chiefly a geologist, so building a system like this is going to be a challenge! Which sensor would be better for my application? I need a fairly accurate reading (within a few mm if possible).How much power would I need for an Arduino and sensor like the two I have linked? How difficult will it be to code the Arduino to collect data from the transducer at set time intervals and then store that data on an SD card or USB?
My research funding is very limited (I have about $400 USD available), which has led me to try and create a couple transducers instead of purchasing one like a Solinst Levelogger (which can get pricey). If anyone could offer some guidance, pointers, or advice I would be eternally grateful. While I am very interested in learning about Arduino and all that can be done with micro-controllers, I need to begin collecting data soon and would really appreciate some "spoon feeding" when it comes to help with this project. This will be my very first Arduino project so I need all the help I can get! Thank you!
I need a fairly accurate reading (within a few mm if possible)
mm of what?
You need to more clearly describe what you want to measure. If you want to measure water pressure (or depth) relative to atmospheric pressure, you need a gauge (also spelled gage) sensor, and it may not be submersed in the water. The Amazon sensor you linked is probably a gauge sensor, meant to be mounted on the outside of a tank, with the fitting communicating to the liquid within.
The ebay sensor obviously cannot be submersed in water or the wiring will be destroyed.
If you want to measure absolute water pressure, i.e. if the sensor is to be submerged, then you need a submersible absolute pressure sensor. Most of those are pretty expensive, but if you find a cheap and reliable one, let us know. You would also need an atmospheric pressure sensor to compensate for weather.
For an extremely cheap, easy to use and reliable data logging solution that requires no programming, I recommend the Sparkfun Openlog. It is an independent module that logs Serial.print() statements from your program, or print statements from a software serial port.
Thank you for your reply! I want to measure water level above the sensor, so it would have to be submerged. I have a barometric logger already in place for my study area (probably should have mentioned that!) so I will be able to calculate water level (psi) above the sensor. I'm thinking of encasing the breakout board sensor on ebay with an epoxy (except for the pressure diaphragm) in order to make it waterproof like they did in the similar project I posted a link to. I know I really need an absolute pressure sensor but as you said they are expensive and I'm looking for cheaper alternatives. I will definitely post here if I find a reasonable absolute sensor! Thank you for the info about Openlog, it really is super cheap!
for pressure , you need to read the data sheets and see the accuracy.
also, environmental conditions, submerged is a whole different world.
that is why submerged or down-hole sensors are so expensive.
You could try some more simple methods such as a float attached to a pulley and an encoder to measure the depth , a long stick with a float on it that you can measure at the top of the well, or if you don’t need accuracy a couple of float switches set at different heights.
Measuring small pressures is difficult and any minor leak or temperature variations in the tubes can cause errors.
You could try a bubbler type pressure sensor with a small air pump (for blood pressure) and a differential gauge sensor (two tube ports, and not barometric pressure sensitive).
Then all the electronics can be above ground.
Leo..