pressure sensor testing part 2

My pressure sensors finally arrived!  I'm stoked to experiment with these models as I believe they have the measurement resolution and electrical specs for my Arduino fuel gauge solution.

First up, unboxing and evaluation.  First thing out of the box I was really surprised at how large they are.  It didn't have any physical measurements on the ordering page, but I had the mistaken impression from the pictures online they would be somewhat smaller and lighter, similar to the 10psi sensor I ordered initially.  the new one is larger, a bit heavier (not unreasonably so) and doesn't come with an integrated cable:

They will still fit my application space, but I'll probably need to consider some sort of mounting bracket to secure it with the fuel line.  Overall build quality seems real good.  Two sensors, exact same spec, just like I ordered - 1.5psi, 1/4 inch NPT thread connection, 0.5V to 4.5V output:

Looking closer at the electrical connection end, standard cable compression sleeve entry and what appears to be a small screw holding the cap on the top:

Backing out the screw I thought would allow the cap to come off to reveal the electrical connections inside.....

........but the cap is actually a full 4 prong indexed plug on it's own - the machine screw secures the cap/connector to the sensor body.  I like that in the design!

Another nice design detail is the rubber gasket on the bottom of the connector, protecting the joint with the sensor.

The terminal block pops out of the cap to reveal good quality screw terminals which are numbered to co-incide with the pin outs on the lable of the sensor.  #1 for 5V+, #2 for sensor circuit ground and #3 for output signal.  There is a 4th terminal with a electrical ground symbol - I suspect this is for sensor body ground, but I'll need to test to be sure: 

I do know I need a better and more scientific set up for true testing and calibration, but here's what I did tonight to try it out.  I used the same poly tube and connections as I did the for 10psi sensor tested previously.  I slowly added water to the tube (in the upright position) and monitored the sensor connected to the Arduino micro-controller.  Using the same Arduino script as before, it is clear to me this sensor is not only much better suited range wise to what I need (1.5 psi vs 10psi), it also seems the output signal is much more stable.  I suspect this output stability is part build quality and part correct range specific, but I'm happy where this experiment and my related theory is headed.  The photo doesn't capture the graphed output on the laptop, sorry.  I'll try and get some screen captures when my test method/system improves.

Still much testing to prove the effectiveness of this method for measuring fuel tank quantity to come.  This is another example of stuff I'm learning on this journey :)