Apparatus for testing carbon monoxide alarms

Details Apparatus for testing carbon monoxide alarms Apparatus for testing carbon monoxide alarms

1999-06-07

2001-09-04

Williams, Hezron (Department: 2856)

Measuring and testing

Instrument proving or calibrating

Gas or liquid analyzer

C340S515000

Reexamination Certificate

active

06282940

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to apparatus for testing the operation of carbon monoxide alarms.
BACKGROUND OF THE INVENTION
Carbon monoxide alarms are now recommended or required for use in residential houses in many jurisdictions in North America, particularly for houses which are heated by natural gas or oil furnaces. Carbon monoxide alarms typically comprise a CO (carbon monoxide) sensor and associated electronics housed in a compact casing, which may be ac or battery operated. CO alarms are designed to respond when the concentration of carbon monoxide exceeds certain preset values over preselected periods of time. For example, the Underwriters Laboratories Standard UL 2034, based upon 10 percent carboxyhemoglobin, requires a CO alarm to sound when the CO concentration exceeds 70 ppm (parts per million) for 240 minutes, or 150 ppm for 50 minutes, or 400 ppm for 15 minutes.
Carbon monoxide alarms are reliable, and they typically include test circuits which allow the consumer to test the electronics. Nevertheless, many consumers have expressed a desire to satisfy themselves that the CO alarm will generate an alarm signal, in the presence of a harmful concentration of carbon monoxide gas.
Consumers have been known to “test” CO alarms by placing them adjacent the exhaust pipe of an automobile, for a period of time. However, this form of testing is generally not effective, since automobile exhaust gas is dirty, and tends to contaminate the CO sensor.
There is a CO alarm testing kit currently available in the marketplace, comprising a glass vial of CO gas and a plastic bag. To test an ac operated CO alarm using this testing kit, the user must plug the alarm into an extension cord, place the alarm and the vial into the bag, close the bag around the extension cord, and break the vial. This testing kit is not always effective, because sometimes the vial leaks, and it is difficult to determine if the vial is full or empty, because CO gas is colourless. This kit is somewhat awkward for use with ac operated alarms, since it requires the user to hold the bag tightly around the extension cord for a period of time. This kit is also relatively expensive, and can be used only once.
There is accordingly a need for an improved CO alarm testing device, which overcomes the disadvantages of the prior art.
SUMMARY OF THE INVENTION
The present invention is directed towards test apparatus for testing the operation of a carbon monoxide alarm of the type having a casing and a CO sensor extending therefrom. The test apparatus comprises a housing sized and configured to receive the casing and to form a gas chamber in communication with the sensor, a CO source for generating a concentration of carbon monoxide within the chamber above a pre-set threshold level for a sufficient period of time to trigger an alarm condition, comprising a flammable material which generates carbon monoxide gas when burned, and a holder located within the housing for holding the source while the source is burned.
The housing preferably comprises walls sized and configured to provide a friction fit around the casing of the alarm. The source of CO gas is preferably a charcoal pellet or small stick of incense. The holder preferably comprises a metal fire box sized to receive the CO source, and support means extending into the gas chamber from a wall of the housing having a slot shaped for receiving the fire box. In one embodiment, the housing comprises a portion of the packaging for the CO alarm.


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