Recall Is Seeking Smoke Detectors After NBS Warning of Self-Ignition

Recall Is Seeking Smoke Detectors After NBS Warning of Self-Ignition

This is the story of the smoke detector that the National Bureau of Standards says can be expected to provide its own fire. As a result, the manufacturer is making extensive efforts to recall and replace a reported 110,000 units.

The United States Consumer Product Safety Commission (CPSC), according to a spokesman, was alerted to the problem when the U. S. Bureau of Prisons reported that an area around a smoke detector was charred as the result of resistor failure with resultant burning of fish paper inside the detector. The CSPC has no record of any actual fire communicating to material outside any detector housing.

The detectors being recalled are 110-VAC units manufactured by BRK Electronics between March 1974 and September 26, 1975. No battery-powered detectors are involved.

Resistor problem

A CPSC memorandum explained that the detector failures were due to the burning out of a resistor, Rl, a lOK-ohm, ½-watt, voltage-dropping carbon resistor.

The memorandum, from the CPSC office of product defect identification, added, “Some of the reports indicated that the failure of Rl resulted in fires within the detectors, primarily involving a ‘fish paper’ insulation and sometimes resulting in the melting of the detector’s external housing.”

In July 1975, the Rl was changed to a 12K-ohm resistor of the same type and size, and an identically-sized R22 resistor was added in parallel with the Rl.

The tests conducted at NBS showed that all failures involved either the Rl resistor in the original detector model or the Rl and R22 in the later model. NBS reported that the fish paper ignited in 50 percent of the failed detectors it examined.

The product defect identification office memorandum explained that “it was not possible for the NBS, through their tests, to clearly establish whether . . . ignition of the insulation could produce a sufficiently intense fire within the detector to ignite nearby combustibles external to the detectors.” However, the memo continued, in the case where a solid wood beam had been charred adjacent to a failed detector, the NBS concluded that if the detector had been on “thin plywood paneling or lowdensity fiberboard, both used extensively in mobile homes,” the failure of the detector “might have produced a secondary self-sustaining fire.”

Most expected to fail

NBS expressed the opinion that most of the detectors under recall will fail, “although it may take several years of operation.”

The CPSC reported that the detectors being recalled “received certification or approval from a number of organizations, including Underwriters Laboratories, Underwriters Laboratories of Canada, International Conference of Building Officials and Code Administrators International, and the California State Fire Marshal’s Office.”

To rectify this problem, BRK is now using wire-wound resistors, which won’t smoke, instead of the carbon or filmtype, and instead of the combustible fish paper, the paper now being used is both flame-resistant and flame-retardant to conform with UL Standard 217 for smoke detectors.

The faulty 110-VAC smoke detectors were made either with pigtail leads for direct connection in a box to the building wiring or with a line cord to be plugged into an electrical outlet. The suggested retail price for these detectors was $39.50.

Model numbers

Both types of detectors were marketed by BRK Electronics and, under private labels, by AMF Industries (AMF), I-T-E Imperial Corporation (I-T-E) and Sears, Roebuck & Company.

The model numbers of the defective units are as follows:

BRK—SS749AC and SS749ACS, both hard wire units, and SS749L and SS749SL, line cord units.

AMF—2000AC, hard wire units, and 2000ACL, line cord units.

I-T-E—IT01-AC, hard wire units.

Sears—9-57049, hard wire units, and 9-57047 and 9-57048, line cord units.

The model numbers are on a label attached to the plastic base that can be exposed by removing the cover. Also on the base is a four-digit date code that completes the identification of the units being recalled. Homeowners are advised to turn off the power at the fuse box or circuit breaker before removing the cover of the hard wire units or to unplug the line cord detectors.

If a homeowner has one of the models listed for recall, except for the Sears units, he should write to BRK Electronics, 780 McClure Avenue, Aurora, Ill. 60507, Attention: Dennis Wm. Clair, Project 749 Director, or phone 312898-9040 and ask for the Project 749 Department. BRK will then send an inspection sheet which will provide further instructions for identifying the units subject to recall, which will be replaced free.

Those who have Sears detectors should get in touch with the nearest Sears store, which will arrange for an inspection and a free replacement of a recalled model.

Dennis Wm. Clair, BRK industrial products manager, who is in charge of the recall operation, said recently that “just over 25 percent” of the faulty detectors have been returned to the factory. He added that notices have been mailed to 9000 mobile home owners and BRK is planning to mail notices to 18,000 mobile home parks.

Indentification difficulties

One of the difficulties in locating the detectors under recall is that thousands were installed in mobile homes and the manufacturers do not know the addresses of all the owners. In other cases, wholesalers sold quantities of detectors to contractors who installed them not only in individual homes, but also in housing developments. BRK has already sent notices to its distributors and asked them for lists of contractors who bought smoke detectors that might be the recall models.

Clair explained that when a defective detector is identified, his company tries to find out if the home is in a housing development or near other houses built about the same time. If such is the case, then BRK tries to find out if other recall models are in the area.

Hopefully, some units being recalled will be spotted during fire department inspections and Clair hopes that alert inspectors will help the recall campaign by initiating action to complete the identification of the faulty units.

Clair believes that “if you make a mistake and take corrective action,” as BRK is doing, then a company is doing all it can to rectify the error and maintain its reputation. □ □

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