Coaxial transducers for cavity-resonator level indicators

Conclusions

The transducers of resonating-cavity level indicators with coaxial resonators have a nonlinear frequency characteristic and, therefore, the sensitivity of secondary instruments will depend on the height of the liquid level. The nonlinearity is particularly noticeable at the initial and end sections, where the slope of the characteristic decreases sharply. In these ranges the dead zone of the level indicator increases.

The existence of three versions of coaxial transducers provides a certain freedom of the choice of the level indicator parameters.

A quarter-waveresonator provides higher sensitivity in the range of maximum levels. It is advantageous to use this transducer for controlling the filling of tanks.

A reversed quarter-wave resonator, whose maximum sensitivity coincides with the initial section of the level scale, should be used for measuring the emptying of tanks.

The half-wave resonator should be used in containers which require the highest sensitivity in the middle part of the scale.

In conclusion it should be noted that the testing of frequency transducers with coaxial lines has shown that the sensitivity of resonating-cavity level indicators which operate with frequency transducers remains practically constant over the part of the scale consisting of 80–85% of the maximum level, above which it begins to drop gradually.