NIOSHTIC-2 Publications Search

Ultra low frequency electromagnetic fire alarm system for underground mines.

Hjelmstad KE; Pomroy WH
Minneapolis, MN: U.S. Department of the Interior, Bureau of Mines, RI 9377, 1991 Jan; :1-11
During an underground mine fire, air can be rapidly depleted of oxygen and contaminated with smoke and toxic fire gases. Any delay in warning miners could have disastrous consequences. Unfortunately, present mine fire alarm systems, such as stench, audible or visual alarms, telephones, and messengers, are often slow, unreliable, and limited in mine area coverage. Recent research by the U.S. Bureau of Mines has demonstrated that ultra-low- frequency electromagnetic signaling can be used for an underground mine fire alarm. In field tests of prototype equipment at five mines, electromagnetic signals from 630 to 2,000 hz were transmitted through mine rock for distances as great as 1,645 m to an intrinsically safe receiver. The prototype system uses off-the- shelf components and state-of-the-art technology to ensure high reliability and low cost. When utilized, this technology would enable simultaneous and instantaneous warning of all underground personnel, regardless of their location or work activity, thereby increasing the likelihood of their successfully escaping a mine disaster. This report presents the theoretical basis for through- the-rock ultra-low-frequency electromagnetic transmission, design of the prototype transmitter and receiver, and the results of in-mine tests of the prototype system.
Mine-fires; Warning-systems; Electromagnetic-noise; Underground-mining; Fire-safety
Publication Date
Document Type
IH; Report of Investigations
Fiscal Year
Identifying No.
NIOSH Division
Source Name
Minneapolis, MN: U.S. Department of the Interior, Bureau of Mines, RI 9377
Page last reviewed: October 8, 2021
Content source: National Institute for Occupational Safety and Health Education and Information Division