Method and device for optically detecting an interface between two fluids and method of setting the parameters for such detection

A device for detecting an interface between fluids, the device comprising:

• a light transmitting unit for a first fluid and a second fluid to pass through, respectively;
• a light source for supplying light to the light transmitting unit;
• and
• a detecting unit for detecting a change of an intensity of the light from the light source which has passed through the light transmitting unit,
• a spectral intensity of the light source, at least one characteristic of an optical path from the light source to the detecting unit, said light transmitting unit occupying a part of the optical path, and spectral detection sensitivity of the detecting unit are selected in accordance with at least one light transmitting characteristic of at least one of the first fluid and the second fluid,
• such that an output difference, between an output of the detecting unit in the presence of light transmitted through the first fluid when the first fluid occupies the part of the optical path in the light transmitting unit and an output of the detecting unit in the presence of light transmitted through the second fluid when the second fluid occupies said part of the optical path in the light transmitting unit, exceeds a set value.

A device for detecting an interface of two fluids, the device comprising:

• a pipe having a light transmitting unit, the pipe being in communication with a vessel, the vessel containing a first fluid and a second fluid with an interface;
• a light source for supplying a light to the light transmitting unit;
• and
• a detecting unit for detecting an intensity change of the light in the light transmitting unit from the light source;
• whereby a spectral intensity of the light source, at least one characteristic of the optical path between the light source and the detecting unit, and spectral detection sensitivity of the detecting unit are selected in accordance with light transmitting characteristics of the first fluid and the second fluid in a manner that an output difference between a first output and a second output exceeds a predetermined value, the first output being of the detecting unit as the first fluid exists in the optical path in the light transmitting unit, and the second output being of the detecting unit as the second fluid exists in the optical path in the light transmitting unit.

A method for setting parameters in a detection process that detects an interface between a first and second fluid comprising the steps of

• (a) determining at least one parameter of said detection process as a function of at least one of the first fluid and the second fluid;
• (b) transmitting light along an optical path,
• wherein a part of the optical path is alternatively occupied by each of the fluids;
• (c) detecting light transmitted along the optical path under a first condition in which the first fluid occupies a part of the optical path and under a second condition in which the second fluid occupies the part of the optical path;
• and
• (d) recognizing an interface as a function of a change in light detected,
• whereby the light transmitted under the second condition differs sufficiently from the light transmitted under the first condition so that the change in light is distinguishable.