Patent US3802249A successfully refreshed from Google Patents.
US3802249A
Expired / Lapsed
US
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Method and apparatus for checking fire detectors
Assignee: National Aeronautics and Space Administration
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Filing: 1972-12-26
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Granted: 1974-04-09
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Expires: 1992-12-26
Abstract
Abstract A fire detector checking method and device are disclosed for nondestructively verifying the operation of installed fire detectors of the type which operate on the principle of detecting the rate of temperature rise of the ambient air to sound an alarm and/or which sound an alarm when the temperature of the ambient air reaches a preset level. The fire alarm checker device of the instant invention uses the principle of effecting a controlled simulated alarm condition to ascertain whether or not the detector will respond. In the preferred embodiment, the checker comprises a hand-held instrument employing a controlled heat source, e.g., an electric lamp having a variable input, for heating at a controlled rate an enclosed mass of air in a first compartment, which air mass is then disposed about the fire detector to be checked. A second compartment of the device houses an electronic circuit to sense and adjust the temperature level and heating rate of the heat source. Actuation of a fire detector of the rate of rise type within a predetermined time interval after applying the heated air mass thereto verifies the soundness of the system. A technique is further disclosed whereby a test for proper operation at a predetermined temperature level may separately or alternatively be performed by the novel device on fire detectors which are triggered at some predetermined temperature level irrespective of the rate of temperature rise.
Inventors
- 👤 G Clawson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 15:04
CPC Classifications
G; G08; G08B; G08B29/00; G08B29/12; G08B29/14; G08B29/145; G01; G01K; G01K3/00; G01K3/08; G01K3/10
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
98 words
A checking device for checking the operation of an installed fire detector, comprising: a casing having therein a plenum which is to be applied over the fire detector to be checked; an adjustable heat source disposed within said casing to effect predetermined temperature characteristics, defined by a predetermined rate of temperature rise, within said plenum; and means for measuring said temperature characteristics from radiation emitted by said heat source, whereby a normal and faultless fire detector to which said device is applied, after setting said predetermined temperature characteristics, sets off an alarm within a given interval of time.
Claim 2
Dependent Claim
98 words
A checking device for checking the operation of an installed fire detector, comprising: a casing having therein a plenum which is to be applied over the fire detector to be checked; an adjustable heat source disposed within said casing to effect predetermined temperature characteristics, defined by a predetermined rate of temperature rise, within said plenum; and means for measuring said temperature characteristics from radiation emitted by said heat source, whereby a normal and faultless fire detector to which said device is applied, after setting said predetermined temperature characteristics, sets off an alarm within a given interval of time.
Claim 3
Dependent Claim
40 words
A checking device as in claim 1, wherein said heat source comprises electrical resistance, said device including means to control a power source to the heat source so as to achieve a predetermined rate of temperature rise of said plenum.
Claim 4
Dependent Claim
38 words
A checking device as in claim 2, wherein said means to control the power source to the heat source comprises a silicon controlled rectifier and a variable resistor connected in the gate circuit of said silicon controlled rectifier.
Claim 5
Dependent Claim
39 words
A device as in claim 2, in which said casing is provided with a pistol grip enabling the device to be hand-held, said pistol grip including a trigger switch, said trigger switch being connected electrically to said power source.
Claim 6
Dependent Claim
23 words
A device as in claim 4, wherein said radiation-sensing element which is disposed to receive radiation from said heat source comprises a photocell.
Claim 7
Dependent Claim
35 words
A device as in claim 2, wherein said means to control power source to heat source comprises a silicon controlled rectifier and a variable resistance connected in the gate circuit of said silicon controlled rectifier.
Claim 8
Dependent Claim
25 words
A checking device as in claim 1, wherein said heat source comprises an incandescent lamp, and wherein said radiation which is measured comprises light radiation.
Claim 9
Dependent Claim
31 words
A device as in claim 4, wherein said means for measuring comprises a meter connected in series with a photocell which is disposed to receive light radiation from said incandescent lamp.
Claim 10
Independent Claim
104 words
A method of determining the operational integrity of an installed fire detector, said method comprising the steps of: applying a plenum over the fire detector to be checked; heating the plenum at a controlled rate by a radiation-emitting heat source; measuring the rate of temperature rise within the plenum by monitoring the radiation emitted by the heat source; adjusting the rate of heating of the heat source so that the rate of temperature rise within the pleNum corresponds to predetermined ratings of the fire detector being checked, thus simulating an alarm condition; and determining whether the fire detector responds to the simulated alarm condition.
Claim 11
Independent Claim
104 words
A method of determining the operational integrity of an installed fire detector, said method comprising the steps of: applying a plenum over the fire detector to be checked; heating the plenum at a controlled rate by a radiation-emitting heat source; measuring the rate of temperature rise within the plenum by monitoring the radiation emitted by the heat source; adjusting the rate of heating of the heat source so that the rate of temperature rise within the pleNum corresponds to predetermined ratings of the fire detector being checked, thus simulating an alarm condition; and determining whether the fire detector responds to the simulated alarm condition.
Claim 12
Dependent Claim
72 words
In an apparatus for checking the operational reliability of an installed fire detector which includes an incandescent heat source for applying heat to the fire detector thereby simulating an alarm condition, the improvement comprises means for measuring the temperature of the heat source by monitoring the radiation emitted therefrom, and means for adjusting the output of the heat source so that said measured temperature corresponds with predetermined characteristics of the fire detector.
Claim 13
Dependent Claim
72 words
In an apparatus for checking the operational reliability of an installed fire detector which includes an incandescent heat source for applying heat to the fire detector thereby simulating an alarm condition, the improvement comprises means for measuring the temperature of the heat source by monitoring the radiation emitted therefrom, and means for adjusting the output of the heat source so that said measured temperature corresponds with predetermined characteristics of the fire detector.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-04-08 | 1977-10-08 | 1978-04-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-08 | 1981-10-08 | 1982-04-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-08 | 1985-10-08 | 1986-04-09 | $7700.00 | Window Closed / Lapsed |