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Wireless Pressure Gauges After Two Years of Service

My DIY wireless pressure gauges are two years old now, I've been using them non stop in my "field-trips", and I think it's time to run some tests and answer the main question about their function that only a certain amount of time could answer:

Can my DIY pressure gauges be trusted?

Allow me to elaborate on the origins of the "doubts":

Firstly - when I built the prototypes, my older "pressure-making solution" (can be seen here) that I used for calibration had the maximum pressure of 400 bar (with a lot of muscle input), so the calibration profile for the 600 bar sensor had to be interpolated. Not ideal. Since I have Pressure Maker II now, I can double-check if the profile is "good".

Secondly - all pressure sensors suffer from degradation, so I was wondering if the Gems Sensors that I used gained any off-set after two years of extensive use.

Thirdly - I used the 12-bit ADC built into the module's microcontroller, a couple of precision resistors, and a simple low pass filter to interface the sensors. This solution is simple and cheap, and it worked surprisingly well in all of my initial tests, so I was wondering if it also stood the "test of time".

As you know - FLUKE multi-meters are expensive not because they are filled with features, but because they have authority - i.e. they have been proven to be trustworthy over time. Tens of years for some models, actually. You can get far cheaper multi-meters with a greater resolution and added functionality, but how can you prove that they will still be good after 15 years of service if their model is only a couple of years old? I guess this can be applied to digital pressure gauges as well.

My solution can't boast that many years of service, of course, but still - two years is like twenty years in DIY gadget years...

I don't have a dead weigh pressure calibration stand (yet - I already have some ideas on how to build one, from industrial scrap, of course), so my pressure reference is the good old and time-proven Parker SCJN-600-01 - a pressure gauge that is better than its spec sheet says it is. If my pressure gauges are as good as the Parker - I am happy.

I have two transmitters in my toolbox - one uses a Gems Sensors 400 bar 0...10V pressure transmitter, and the other - 0...600 bar 4...20 mA transmitter. This is the test setup:

And these are the results (readings in bar):

And some pictures:

Conclusions:

• Gems pressure sensors once again proved to be very precise. Zero drift even after two years of use.
• Apparently the very simple precision-resistor-based solution to interface an industrial sensor to a micro-controller is bulletproof.
• If you use large SMD components, even DIY gadgetry can last.
• I am also (pleasantly) surprised how sturdy the 3D-printed PLA bodies turned out to be. I've dropped the transmitters more times than I care to admit - and they are still in one piece. Apparently, PLA is also resistant to mineral oil. Three cheers for 3d printing!

Now I know I can trust my gadgets. And I can prove why.