Hello. I am interested in making a version of the OpenCTD CTD device with the 2 inch housing available from Blue Robotics. The OpenCTD design pots three temperature sensors, a conductivity sensor and a pressure sensor in about 5 inches of epoxy in a PVC pipe. I would rather use penetrators for these sensors. The diameters of the sensors are: 12 mm (conductivity probe), 2.8 mm (temperature probe) and 5.8 mm (pressure sensor). Is there an easy way to do this? Thanks!
Hi @bmbebout, welcome to the forum 
I’m unsure how long the sensors are that you’re talking about, or how large the wires are, but it may be possible to pot them in our potted penetrators? Ideally the cable jacket can butt up against the shoulder, to help prevent push-through. The temperature sensors may be too small for that, but you could consider adding a washer to help support the sensor, and inject epoxy to either side of it.
From a quick look it seems like the recommended pressure sensor is a similar cost to our standard ones, with seemingly similar specs, which could be worth a look given you’re intending to use one of our enclosures. I’m unsure what kind of measurement scenario you’re aiming for though - our standard pressure sensors require daily drying, and it’s unclear to me whether the Sparkfun ones do, despite the sensor itself being from the same manufacturer, and an apparently older model.
Hi there. Thanks so much for the response. Here are the sensors I was planning on using:
Conductivity: Atlas Scientific Mini Conductivity Probe K 1.0 #ENV-20-EC-K1.0, https://atlas-scientific.com/probes/mini-e-c-probe-k-1-0/
Pressure sensor: SparkFun Pressure Sensor Breakout - MS5803-14BA, https://www.sparkfun.com/sparkfun-pressure-sensor-breakout-ms5803-14ba.html
Temperature sensor: Adafruit Platinum RTD Sensor - PT1000 - 3 Wire 1 meter long, https://www.adafruit.com/product/3984
I think that the conductivity sensor would work with the wire potted as you suggest (I think), but the temperature sensor is not waterproof. Therefore, I was looking for a way to pot the entire sensors as if they were a thicker wire. As nearly as I can tell, that would not work with these sensors. The pressure sensor is on a board, and gets buried in epoxy (but has developed leaks). The design philosophy of the OpenCTD is to make things affordable, but your pressure sensor is really appealing as the one I have used previously (on a circuit board) is very hard to pot and seal. Daily drying is not at all a problem as I usually deploy these things on a line on a dock or a boat.
Thanks again for the help!
Hi @bmbebout -
@kurt_bluerobotics solved this challenge without potting via glands, as detailed in his post / doc here.
For pressure, it would likely be far easier to use a Bar30 or Bar30XT?
The Celsius fast response temperature sensor is also quite capable and easier to integrate… an upcoming update will make it potting-free!
Thanks so much. The cable glands look really nice. Any time frame on the potting-free cable sensor? Thanks again.
Hi @bmbebout -
The potting-free Celsius is still early in development - I would hope it would be for sale by Q2 or Q3 next year, assuming there are no issues getting it into production. To be clear - it will have the same form factor as the existing Celsius sensor, intended for 10mm holes on a bulkhead (not sure what you mean by “cable sensor.” )
Sorry, I meant temperature sensor. Thanks again,