Apparatus and method for detecting liquid level in a clear or partially clear container

1. A filter trap apparatus, comprising:

a trap bowl configured to accumulate liquid droplets from a filter, as a liquid content, the trap bowl comprising a section that extends in a vertical direction, and a transparent vertical prism, the transparent vertical prism including a face that forms a vertical transparent surface facing against a content of the section, the face having a first angle of total reflection when the content of the section is a gas, and a second angle of total reflection when the content of the section is the liquid content;

a light source, configured to emit a light beam incident on the face at an angle of incidence;

a first optical receiver, wherein the first optical receiver is a light receiver, wherein the angle of incidence results in reflection of the light beam, striking the first optical receiver, when the face has the first angle of total reflection, and results in refraction of the light beam, missing the first optical receiver, when the face has the second angle of total reflection;

a second optical receiver, wherein the second optical receiver is an offset optical receiver from the first optical receiver; and

a third optical receiver, wherein the third optical receiver is a diametrically opposed optical receiver from the first optical receiver;

wherein the first optical receiver, the second optical receiver, and the third optical receiver are on a same plane that is normal to a vertically extending center axis of the trap bowl.

2. The filter trap apparatus of claim 1 , wherein the first optical receiver is a receiver element of an optic emitter/receiver, and the light source is an emitter element of the optic emitter/receiver.

3. The filter trap apparatus of claim 2 , further comprising an adjustable emitter/receiver support, the adjustable emitter/receiver support including a support element configured to attach to the optic emitter/receiver, and a selectively actuated elevating support that supports the optic emitter/receiver at a selective elevation in the vertical direction.

4. The filter trap apparatus of claim 1 , wherein the face is a first face, and the vertical transparent surface is a first vertical transparent surface, wherein the transparent vertical prism further comprises a second face, wherein the second face forms a second vertical transparent surface facing against the content of the section, the second face having the first angle of total reflection when the content of the section is the gas, and the second angle of total reflection when the content of the section is the liquid content.

5. The filter trap apparatus of claim 4 , wherein the first face and the second face intersect at a vertex, the vertex being vertical, wherein an included angle is arranged symmetrically about a reference bisector line the extends outwardly, in a radial direction, from the vertex.

6. The filter trap apparatus of claim 5 , wherein the light source is configured to emit the light beam as a collimated light beam, and to emit the collimated light beam in a direction approximately parallel to the reference bisector line.

7. The filter trap apparatus of claim 6 , wherein the included angle is about 90 degrees and the collimated light beam strikes a first gas with an angle of incidence of about 45 degrees.

8. The filter trap apparatus of claim 1 , wherein the transparent vertical prism is made of polycarbonate.