Corrosion resistant refractive and adsorptive type optical liquid level sensors
First Claim
1. A corrosion-resistant optical liquid level sensor adapted to determine the level of liquid in a container formed of polytetrafluorethylene perfluoralkoxy material, comprising:
- a light source;
said container having first, second and third windows severally formed of said material;
transmitting means for transmitting light from said source through said first window into said container;
primary detection means operatively arranged to measure the intensity of light passing through said second window;
secondary detection means operatively arranged to measure the intensity of light passing through said third window; and
comparator means for monitoring the integrity of the optical path between said source and said primary and secondary detection means as a function of the intensities of light measured by said primary and secondary detection means.
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Accused Products
Abstract
Two types of optical liquid level sensor are disclosed. In the first refractive-type (20,65), light is selectively refracted by the particular fluid(s) in a plug recess between primary and secondary detectors (D1,D2). The output signal from either detector indicates whether the sensor is above or below the liquid level. The signals of the respective detectors are cross-compared and used to corroborate one another. In the second absorptive-type (100), light at a particular wavelength is passed through a body chamber (86'"'"'), which is exposed to the liquid whose level is to be sensed. Such light is selectively absorbed by the liquid. A detector (D) is arranged to measure the intensity of such light as has passed through the chamber, and to indicate the level of liquid in said chamber.
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Citations
12 Claims
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1. A corrosion-resistant optical liquid level sensor adapted to determine the level of liquid in a container formed of polytetrafluorethylene perfluoralkoxy material, comprising:
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a light source; said container having first, second and third windows severally formed of said material; transmitting means for transmitting light from said source through said first window into said container; primary detection means operatively arranged to measure the intensity of light passing through said second window; secondary detection means operatively arranged to measure the intensity of light passing through said third window; and comparator means for monitoring the integrity of the optical path between said source and said primary and secondary detection means as a function of the intensities of light measured by said primary and secondary detection means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. The method of determining the level of liquid in a container, said container being formed of a polytetrafluorethylene perfluoralkoxy material and having a surface facing into said container, said container also having a first window forming a portion of said surface and through which light may enter said container and having second and third windows forming portions of said surface and through which light may exit said container, said second and third windows being spaced from one another, which method comprises the steps of:
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transmitting light into said container through said first window; directing light passing through said first window to said second window when said first window is submerged in said liquid; directing light passing through said first window to said third window when said first window is not submerged in said liquid; measuring the intensity of such directed light passing through said second window; measuring the intensity of such directed light passing through said third window; and comparing the measured intensities of light passing through said second and third windows; thereby to measure the integrity of the optical paths between said windows as a function of said measured light intensities.
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12. The method of determining the level of liquid in a container, said container being formed of a polytetrafluorethylene perfluoralkoxy material and having a surface facing into said container and adapted to be exposed to the particular liquid the level of which is to be sensed, said container having a first window forming a portion of said surface and through which light may enter said container and also having a second window forming another portion of said surface and through which light may exit said container, the optical path between said windows being unaffected by the nature of fluid in said container, which method comprises the steps of:
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transmitting light through said first window into said container; selectively absorbing a selected wavelength of said light as a function of the fluid in said container; transmitting light from said container through said second window; and measuring the intensity of light passing through said second window at said selected wavelength; thereby to indicate whether said first window is above or below the level of liquid in said container.
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Specification