Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2000-03-09
2001-03-06
Hofsass, Jeffery (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S514000, C340S515000, C340S693600, C340S693800
Reexamination Certificate
active
06198399
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a portable device for testing the operation of a smoke detector by safely producing smoke in close proximity to a smoke detector to be tested.
BACKGROUND OF THE INVENTION
The number of fires in residences and businesses and the destruction caused thereby have resulted in the pervasive use of smoke detectors and smoke detection systems that provide early warning of a fire or dangerous condition by sensing smoke and sounding an audible alarm. Since 1969, when the first commercial smoke detectors became readily available, the number and type of smoke detectors have increased exponentially. While the vast majority of residences and commercial buildings are, in fact, now equipped with some kind of smoke detectors, that alone has not eliminated the problems or destruction resulting in fires, even in buildings in which smoke detectors are installed. Fire remains the second leading cause of death in the home, with over 3,500 deaths and billions of dollars in property damage attributable thereto annually.
In the last 30 years, smoke detector design and functioning have improved, and the latest incarnation of smoke detectors now are guaranteed by the manufacturer to be effective for 10 years on the condition that the batteries are properly maintained, while previously only a 3 year warranty was available. Most of the smoke detectors presently in use have outlived their warranties and useful life, however, and may be defective, although the homeowner is unaware of the defect. The confirmation and ramifications of the gradual failure of smoke detectors is underscored by a trend indicating that, while the number of total fire damage and death is decreasing, probably due to the use of smoke detectors, the instances of fires in which smoke detectors failed is increasing. That is, the National Fire Data Center, a division of the Federal Emergency Management Agency, has determined that the number of instances of fires where an alarm was present but did not operate is increasing. The present invention is dedicated to reversing this trend by making the testing of smoke detectors less expensive and easier and safer to accomplish.
The operation of most smoke detectors relies upon the life of a battery installed therein. Generally, smoke detectors work in one of two ways. Some smoke detectors work by sensing the presence of particulates in smoke by detecting an interruption in photoelectric energy, i.e. a beam of light is interrupted, while others employ the use of an ionization of an air sample to detect smoke. In both the photocell and ionization smoke detectors, an audible alarm mounted within the smoke detector housing is triggered upon the detection of smoke. Because the photoelectric/ionization detection circuit and the audible alarm circuit require a power supply for operation, the power supply generally supplied by an on-board battery, the operation and effectiveness of the smoke detector is completely dependent upon the integrity and life remaining in the battery. While other defects in the detection and alarm circuits could still prevent effective operation of the smoke detector, as discussed in more detail below, the failure of the battery would render the smoke detector useless. Thus there is defined a need for a device that tests the operation of a smoke detector, including the integrity and life left in the battery providing power to the smoke detector.
One method for testing smoke detectors and particularly for testing the life of the battery therein is to bypass the photoelectric detection circuit to test the audible alarm circuit. Most often this test is done by pressing a button mounted on the smoke detector itself which, effectively, bypasses the detection circuit and triggers the alarm to sound. For a number of reasons this method for testing a smoke detector is disadvantageous. First, smoke detectors are generally mounted high on walls or on a ceiling, away from the floor, and they are not readily accessible for a user to test in this manner. To operate the test button on a smoke detector a user often must elevate himself and reach up to push the test button. Climbing on a ladder or chair or using other means for elevation or to reach the button on a high mounted smoke detector presents an increase risk of injury from falling, is inconvenient and requires the user to have a ladder or other device on which he can elevate himself available.
In addition, the test of a smoke detector by depressing the on-board button merely tests the operation of the audible alarm circuit by bypassing the photoelectric/ionization detection circuit. It does not test the sensitivity or operation of the photoelectric/ionization detection circuit. A problem in the photoelectric/ionization detection circuit, such as a bad photoelectric sensor or ionization chamber, or one that is not operating properly due to dust accumulated thereon, would not be evident by operation of the test button. That is, the test button could still close the circuit and trigger the audible alarm even if the photoelectric/ionization sensor was completely defective, and the user would mistakenly believe that the smoke detector was operating properly.
It is desirable to provide a device for testing the operation of a smoke detector, including the life of the battery and the operation of the detection and alarm circuits, by simulating the conditions under which the detector is designed to operate. The controlled creation of smoke in close proximity to the smoke detector is effective as a means to test a smoke detector, but it is desirable to do so without requiring the use of an open flame near the smoke detector since a flame presents an increased risk of damage or injury if the flame is positioned too close to the smoke detector or the wall or ceiling on which it is mounted. Preferably a smoke detector test device would generate smoke in the vicinity of the smoke detector by causing a combustible substance to smolder for a very short period of time without creating a flame, thereby creating smoke in sufficient volume to be perceived by the smoke detector which then triggers audible alarm to be activated. To make the use of such a test device safe, the user should be able to place it in close proximity to the smoke detector without requiring the user to position himself near the smoke detector, as on a ladder or stool, which is inconvenient and presents an increased risk of falling and injury.
Most manufacturers recommend testing of smoke detectors every 30 days. Recently government sponsored programs have sought to encourage testing of smoke detectors one to two times per year. With the use of a smoke detector test device as infrequently as once or twice a year, it would be advantageous to provide a smoke detector test device that is inexpensive to manufacture and operate so that a one time use of the device is reasonable. An inexpensive device with a combustible element affixed thereto that smolders when ignited, without creating or resulting in an open flame being present, and one which is readily attached to a broomstick or other extended handle commonly found around the home, would serve such purpose effectively and inexpensively. Such device would also be a true test of the operation of the smoke detector and thereby overcomes the disadvantages of the prior art. A goal of a simple and inexpensive test device is to make the testing of smoke detectors every 30 days feasible.
U.S. Pat. No. 4,271,693 to Bute provides a telescoping smoke detector test device which includes a smoldering tip that is ignited by an electric supply mounted thereon. The telescoping arm can be extended so that the smoldering tip is sufficiently near the smoke detector to trigger its operation if the detector is working properly. The '693 Bute device is disadvantageous, however, because of the complexity of the manufacturing and assembly of the device. The inclusion of a telescoping extensible arm and an electric source wired to ignite the smoldering tip can be dramatically simplified by merely provi
Hofsass Jeffery
Macke R. Christian
Tang Son M.
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