Method and apparatus for detecting hydrocarbon fuels in a vapor state with an absorber-expander member
First Claim
1. A method for detecting the presence of a hydrocarbon analyte in at least one of a liquid and a vapor state comprising the steps of:
- positioning an optical fiber in a location for detection of said hydrocarbon with an absorber-expander member mechanically coupled to said fiber to produce a change in light transmission in said fiber upon absorption of said hydrocarbon analyte by, and expansion of, said absorber-expander member, said absorber-expander being hydrophobic and being selected to have multiple reversible expansion and contraction cycles upon absorption and evaporation of said hydrocarbon analyte by said absorber-expander; and
detecting a change in light transmission in said fiber.
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Accused Products
Abstract
A method and apparatus for detecting the presence of hydrocarbon analyte in at least one of a liquid and vapor state. The apparatus (21) includes an optical fiber (22), an absorber-expander (31) mechanically coupled (32) to the optical fiber (22) to produce a change in transmission of light along the fiber (22) upon absorption of the hydrocarbon (33). The absorber-expander (31) is selected to absorb hydrocarbons, but not water, and to be capable of multiple reversible expansion and contraction cycles without significant structural degradation. Methyl terminated, silica and iron oxide filled, dimethyl polysiloxane provides a material which will experience substantial swelling in the presence of a hydrocarbon and yet is substantially reversible on desorption of the hydrocarbon from the absorber-expander (31). The method includes positioning an optical fiber (22) having such an absorber-expander (31) for absorption of hydrocarbons and detecting the decrease in light transmission produced by expansion of the absorber-expander (31), for example, by one of microbending and axial misalignment. The location of the absorber-expander (31) along strand (22) can be determined by optical time domain reflectometry or by digital sensing nodes (122), and multiple couplings (57) and biasing couplings (153) for mounting the absorber-expanders (152) to the optical fiber (151) can be used to enhance sensitivity.
45 Citations
50 Claims
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1. A method for detecting the presence of a hydrocarbon analyte in at least one of a liquid and a vapor state comprising the steps of:
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positioning an optical fiber in a location for detection of said hydrocarbon with an absorber-expander member mechanically coupled to said fiber to produce a change in light transmission in said fiber upon absorption of said hydrocarbon analyte by, and expansion of, said absorber-expander member, said absorber-expander being hydrophobic and being selected to have multiple reversible expansion and contraction cycles upon absorption and evaporation of said hydrocarbon analyte by said absorber-expander; and detecting a change in light transmission in said fiber. - View Dependent Claims (2, 3, 4, 5)
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6. A method of making a hydrocarbon detection apparatus comprising the steps of:
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selecting a silicone rubber member as an absorber-expander for a hydrocarbon in at least one of a liquid state and a vapor state, said silicone rubber member being selected to absorb and expand in the presence of said hydrocarbon and to recover and contract to a substantially undegradated condition in the absence of said hydrocarbon; mechanically coupling said silicone rubber member to a fiber optic strand in a manner producing one of microbending and axial misalignment of said strand upon expansion of said silicone rubber member; and optically coupling detection apparatus means to said strand for detection of the occurrence of decreased light transmission along said strand. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A detection apparatus for detecting the presence of at least one of a liquid hydrocarbon and a hydrocarbon vapor comprising:
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an optical fiber; an absorber-expander member mechanically coupled to said optical fiber to produce a change in transmission of light along said optical fiber upon absorption of said hydrocarbon, said absorber-expander being formed of a hydrophobic hydrocarbon-absorbing rubber material selected to expand upon absorption of said hydrocarbon and selected to retain sufficient structural integrity to permit repetitive use; and detection apparatus optically coupled to said optical fiber for detection of a change in light transmission along said fiber. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49)
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50. A hydrocarbon detection apparatus comprising:
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an optical fiber; a methyl terminated, silica and iron oxide filled dimethyl polysiloxane rubber member mechanically coupled to said optical fiber to produce microbending of said fiber upon absorption of at least one of a liquid hydrocarbon and a hydrocarbon vapor by said red silicone rubber; and microbend detection apparatus optically coupled to said fiber to detect the presence of a microbend in said fiber.
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Specification