The FA 200/4 fill level indicator is usually installed in stationary tanks operated without pressure in a cubic build. Approved as overfilling protection according to WHG §19 and ATEX for flammable liquids of hazard classes AI, AII and B.
The instrument is based on the float principle, i.e. the ball floating on the liquid level will indicate the fill level on the scale installed in the front via a float rod and shaft.