Patent US3742476A successfully refreshed from Google Patents.
US3742476A
Expired / Lapsed
US
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Fluid flow indicating system
Assignee: APEX SUPPLY CO
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Filing: 1971-11-05
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Granted: 1973-06-26
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Expires: 1991-11-05
Abstract
Abstract A system utilizing a probe for ascertaining the rate of flow of a stably maintained fluid, i.e., a fluid which is not being subjected to a change from a liquid to a gas or vapor, or vice versa, the probe being of the type in which the temperature responsive sensor thereof is heated, tending to maintain the sensor at a substantially constant temperature.
Inventors
- 👤 R Withrow
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 14:16
CPC Classifications
G; G01; G01P; G01P13/00; G01P13/0006; G01P13/006
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
253 words
A system for sensing a change of temperature of a liquid, said system comprising: A. a source of current; B. a temperature responsive sensing element (11 or 59); C. an electric heating member (25); D. a circuit connected across the source of current including in series said temperature responsive sensing element and said electric heating member; E. a biasing resistor (17); F. a unijunction transistor (19); G. a circuit connected across the source of current including in series said biasing resistor (17), said unijunction transistor (19) and said electric heating member (25); H. a capacitor (15); I. a conductor connected with one side of the source of current and with said unijunction transistor, said capacitor being connected in parallel with the temperature responsive sensing element; J. a silicon-controlled rectifier (21); K. a circuit connected across the source of current including in series said rectifier and said electric heating member; L. a conductor connecting the unijunction transistor with the rectifier causing increase of current flow through the electric heating member; M. a second capacitor (20) connected across the source of current in parallel with said temperature responsive sensing element; N. an alarm (29); O. a heat-responsive time-delay device (27) in heat exchange relationship with the electric heating member; P. a circuit connected across the source of current including in series the time-delay device and the alarm; Q. a heating element (13) in heat exchange relationship with the temperature responsive sensing element; R. a circuit connected with the source of current and the heating element.
Claim 2
Independent Claim
253 words
A system for sensing a change of temperature of a liquid, said system comprising: A. a source of current; B. a temperature responsive sensing element (11 or 59); C. an electric heating member (25); D. a circuit connected across the source of current including in series said temperature responsive sensing element and said electric heating member; E. a biasing resistor (17); F. a unijunction transistor (19); G. a circuit connected across the source of current including in series said biasing resistor (17), said unijunction transistor (19) and said electric heating member (25); H. a capacitor (15); I. a conductor connected with one side of the source of current and with said unijunction transistor, said capacitor being connected in parallel with the temperature responsive sensing element; J. a silicon-controlled rectifier (21); K. a circuit connected across the source of current including in series said rectifier and said electric heating member; L. a conductor connecting the unijunction transistor with the rectifier causing increase of current flow through the electric heating member; M. a second capacitor (20) connected across the source of current in parallel with said temperature responsive sensing element; N. an alarm (29); O. a heat-responsive time-delay device (27) in heat exchange relationship with the electric heating member; P. a circuit connected across the source of current including in series the time-delay device and the alarm; Q. a heating element (13) in heat exchange relationship with the temperature responsive sensing element; R. a circuit connected with the source of current and the heating element.
Claim 3
Dependent Claim
24 words
A system as defined in claim 1, characterized in that the temperature responsive sensing element is of the type having negative coefficient of resistance.
Claim 4
Dependent Claim
24 words
A system as defined in claim 1, characterized in that the temperature responsive sensing element is of the type having positive coefficient of resistance.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-25 | 1976-12-25 | 1977-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-25 | 1980-12-25 | 1981-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-25 | 1984-12-25 | 1985-06-26 | $7700.00 | Window Closed / Lapsed |