The Mine Safety and Health Administration (MSHA) is warning underground coal mine operators of an interference problem between proximity detection systems (PDS) and respirable dust sampling devices when both devices are in use at the same time.
MSHA has observed that dust sampling devices function properly. Mine operators who do not have proximity detection systems are not affected by this notice; dust sampling must continue at these mines (and, as will be discussed, at all underground coal mines) as required by MSHA’s final respirable coal mine dust rule.
MSHA’s final rule on Proximity Detection Systems for Continuous Mining Machines in Underground Coal Mines requires that proximity detection systems be installed to prevent interference that adversely affects the performance of any electrical system. 30 C.F.R § 75.1732(b)(5).
While investigating reports of interference between PDS and respirable coal mine dust sampling devices, MSHA found that other devices or equipment may also cause electromagnetic interference that adversely affects the performance of the PDS.
Devices, other than respirable coal mine dust sampling devices, that can cause interference with a PDS include gas detectors, hand-held radios, and trailing cables. Interference occurs when these devices are placed within several inches of the miner-wearable component of the PDS. This interference can disable the protections designed to stop the machine before a miner is contacted.
MSHA is working with mine operators, manufacturers, and the National Institute for Occupational Safety and Health (NIOSH) to identify solutions.