Rosemount Radar Level Transmitter


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I work in petroleum industry and we mounted rosemount radar 3300 Level Transmitter (LT) (6 years back :p ). One day suddenly this LT goes 0% when level was 100%. process liquid is naphta at around 110 dec C. temp at 110 should not be issue by radar manual temp - press chart i found that LT should work at 110deg C.

I understand that since its not configured for interface. If water level comes in chamber it may cause radar to show low level, but possibility of water is ruled out at such temp. Also I had set fault action to high. if Tx fails, it should have generated 100%. Moreover a power reset (off power than On) makes this Tx reading fine.

If somehow a peak is read by Tx near lower nul zone (0%) due to some material sticking at guided rod (faulty peak read), power reset should not make it disappear.

We are using co axial type GW which also rules out interference with chamber flange or walls.

In my view if peak goes above upper null zone that time level might become zero, but does power reset causes peak to come below upper nul zone.

can anyone help me to rectify the issue? also how can I configure Tx fail alarm to DCS, Tx might generate digital parameters other than 4-20mA?