US4349282A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Transducers
Assignee: SPILL-FIRE ALARM SYSTEMS Ltd (BY CHANGE OF NAME FROM MYLHURST LIMITED) A Co OF UNIED KINGDOM
•
Filing: 1980-12-09
•
Granted: 1982-09-14
•
Expires: 2000-12-09
Abstract
Abstract A transducer has a chamber containing a substance having a monitorable physical and/or chemical property, for example electrical conductivity, which property changes in correspondence with a change in an external influence, for example, temperature. In one embodiment, the chamber is of elongate form and changes in said monitorable property in any part of the substance along the length of the chamber are monitored by a detection means. In a further embodiment the substance is arranged to undergo an abrupt change in the said property thereof, for example, due to a phase change in the said substance, in response to a predetermined change in the external influence, and detection means is provided to detect such abrupt change.
Inventors
- 👤 Raymond W. Norfolk
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 17:07
CPC Classifications
G; G01; G01P; G01P5/00; G01P5/10; G01K; G01K11/00; G01K11/12; G01K13/00; G01K7/00; G01K7/16; G01K7/26
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
74 words
A temperature monitoring device comprising an elongate chamber in the form of a length of tubing containing a solution which undergoes an abrupt change in a physical property thereof due to crystallisation of a substance out of said solution saturated with said substance in response to a predetermined change in the temperature of all or a portion of said solution, and monitoring means for monitoring said property and sensitive to said abrupt change therein.
Claim 2
Dependent Claim
74 words
A temperature monitoring device comprising an elongate chamber in the form of a length of tubing containing a solution which undergoes an abrupt change in a physical property thereof due to crystallisation of a substance out of said solution saturated with said substance in response to a predetermined change in the temperature of all or a portion of said solution, and monitoring means for monitoring said property and sensitive to said abrupt change therein.
Claim 3
Dependent Claim
49 words
A temperature monitoring device as specified in claim 1 wherein: the abrupt crystallisation of said substance influences radiation along the length of said chamber, by reflection, or deflection; and said monitoring means is a radiation device operable to respond to changes in radiated energy passing through said saturated solution.
Claim 4
Dependent Claim
62 words
A temperature monitoring device as specified in claim 1 wherein: said saturated solution is in fluent form; and said monitoring means includes a motor driven pump, continuously circulating said fluent saturated solution along the length of said chamber, and means for sensing any change in viscosity due to abrupt crystallisation of said substance resulting in a change of pressure in said solution.
Claim 5
Dependent Claim
124 words
A temperature monitoring device comprising an elongate chamber in the form of a length of flexible tubing, containing electrodes at opposite ends thereof and an electrically conductive medium extending between said electrodes, said medium comprising a saturated solution of an electrolyte the electrical conductivity of which undergoes an abrupt fall due to crystallisation of said electrolyte out of the solution in response to a predetermined fall in the temperature thereof, and an electrical detection means including an a.c. bridge circuit for monitoring the conductivity between said electrodes so as to produce an electrical output in response to detection of a conductivity change due to occurrence of said predetermined change in the temperature of said medium at any position along the length of the chamber.
Claim 6
Dependent Claim
124 words
A temperature monitoring device comprising an elongate chamber in the form of a length of flexible tubing, containing electrodes at opposite ends thereof and an electrically conductive medium extending between said electrodes, said medium comprising a saturated solution of an electrolyte the electrical conductivity of which undergoes an abrupt fall due to crystallisation of said electrolyte out of the solution in response to a predetermined fall in the temperature thereof, and an electrical detection means including an a.c. bridge circuit for monitoring the conductivity between said electrodes so as to produce an electrical output in response to detection of a conductivity change due to occurrence of said predetermined change in the temperature of said medium at any position along the length of the chamber.
Claim 7
Dependent Claim
130 words
A temperature monitoring device of the type comprising an elongated, hollow tube having opposite sealed ends defining a chamber therebetween; a pair of electrodes, each at an opposite end of said tube within said chamber, said electrodes forming part of an electrical monitoring circuit and a medium filling said chamber which changes its electric conductivity in response to a change in temperature, characterized by: said electrodes having non-corrosive tips of platinum; said tube being formed of flexible black, thin walled, plastic tubing of small bore; and said medium being an aqueous ionic salt solution saturated with potassium nitrate, normally in liquid state, at -20° C., but subject to abrupt, sudden crystallisation of salts out of said solution in response to a reduction of temperature to thereby trigger said monitoring circuit.
Claim 8
Dependent Claim
130 words
A temperature monitoring device of the type comprising an elongated, hollow tube having opposite sealed ends defining a chamber therebetween; a pair of electrodes, each at an opposite end of said tube within said chamber, said electrodes forming part of an electrical monitoring circuit and a medium filling said chamber which changes its electric conductivity in response to a change in temperature, characterized by: said electrodes having non-corrosive tips of platinum; said tube being formed of flexible black, thin walled, plastic tubing of small bore; and said medium being an aqueous ionic salt solution saturated with potassium nitrate, normally in liquid state, at -20° C., but subject to abrupt, sudden crystallisation of salts out of said solution in response to a reduction of temperature to thereby trigger said monitoring circuit.
Claim 9
Dependent Claim
30 words
A sensor as specified in claim 5 wherein: said chamber in addition to said aqueous ionic salt solution includes a small volume filled with an inert gas such as nitrogen.
Claim 10
Dependent Claim
24 words
A sensor as specified in claim 5 wherein: said aqueous ionic salt solution includes ethylene glycol, boric acid, ammonium hydroxide and said potassium nitrate.
Claim 11
Dependent Claim
22 words
A sensor as specified in claim 5 wherein: the ionic salt in said aqueous solution is selected from lithium, sodium or potassium.
Claim 12
Dependent Claim
33 words
A sensor as specified in claim 5 plus: a flexible mat attachable on the surface of a cryogenic tank, said elongated flexible temperature sensor being convoluted on, and attached to, said flexible mat.
Claim 13
Dependent Claim
35 words
A sensor as specified in claim 5 wherein: said flexible tubular body includes a flexible conductor extending from one of said electrodes at one end thereof, with said chamber, to the other said end thereof.
References Cited (Backward Citations)
US2996917A
Cited
US3332280A
Cited
GB1190671A
Cited
GB1326752A
Cited
US3765243A
Cited
US3914688A
Cited
US3974317A
Cited
US3864976A
Cited
GB1465515A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-09-13 | 1986-03-15 | 1986-09-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-09-13 | 1990-03-15 | 1990-09-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-09-13 | 1994-03-15 | 1994-09-14 | $7700.00 | Window Closed / Lapsed |