CAI_Support said:
Dr. Lou set up this pump control with the sensor he mentioned and WebControl running for years.
Hold up there, more like a little over 1 year, not years. Check back with me in 2015 and I'll let you know.
I am potentially pushing my luck withe the transducer because it is located below the water level, meaning that water could get into the sensor and contact the guts of the device. In fact, I am quite certain water has gotten inside of the devices. The specs say you shouldn't do that. But they keep working. I actually have 6 transducers that are all probably wet on the inside. None have failed in over a year of being wet. I also tried a GE sensor, it failed early on. I don't know why, but I suspect it was the water. I never tried a second GE model.
If failure is not an option, I suggest using two sensors in parallel and set some sort of alarm if the two don't agree. Failure would probably result in a grossly abnormal reading such that you could write your plc code to ignore it, use the other sensor, and alert you to the problem.
In fact, no matter what system you are using, if failure is not an option, I suggest some method of backup. Perhaps just an alarm system water contact from GRI set high enough that it should never get wet. They are pretty much passive devices that if they get wet they close the circuit. This could easily wire up to the digital inputs on the cai, while the pressure transducer goes to the analog, giving you a precise level.