I  apply NH3 using a Raven supercooler.  I have to replace the sensor on the flowmeter every two years or so. Does anyone else have problems with this sensor, and if so have you figured out a reason why? I install it correctly-- hand tighten slowly until it just bottoms out and then back off 1/4 -1/2 turn until the orientation groove on the sensor is parallel to the flowmeter body.  Thanks.