Wednesday, February 4, 1998

Coal mine dust sampling cassettes, used by mine operators to measure respirable dust levels in coal mines under Mine Safety and Health Administration (MSHA) requirements, are being replaced by manufacturer Mine Safety Appliances (MSA) after determining that some of the cassettes may have been improperly assembled. MSA has committed to replace approximately 27,000 dust cassettes manufactured between May and December 1997.

According to MSA, some dust cassettes were assembled with improperly positioned "check" valves which could obstruct flow through the cassette. This condition could cause some sampling devices to either shut down before the end of the sampling shift or not maintain proper flowrate. Problems in using some cassettes were first reported by MSHA personnel.

MSA estimates that approximately 8 percent of the 27,000 cassettes may be affected and has committed to immediately remove from service any questionable cassettes by promptly replacing all the unused cassettes in the possession of mine operators. To accomplish this exchange quickly and minimize disrupting bimonthly or any other required sampling, mine operators are urged to immediately return to MSA cassettes (Part Number 803462) with serial numbers ranging from 50345749 through 50383599. For additional information, contact MSA at 1-800-MSA-2222.

Because some questionable cassettes already have been used by mine operators, MSHA is visually examining all samples submitted to its laboratory in Pittsburgh, Pa., and voiding those that have been collected using dust cassettes with improperly positioned check valves.

Respirable dust samples are collected in coal mines by both MSHA and mine operators as part of the overall program to prevent black lung. Each dust cassette, about the size of a fifty-cent piece, contains a filter on which a sample of respirable dust from the mine air is collected using a sampling pump. Over 85,000 dust cassettes are used annually.

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