Pub. 42004-195E
GAI-Tronics Corporation 400 E. Wyomissing Ave. Mohnton, PA 19540 USA
610-777-1374
800-492-1212
Fax: 610-796-5954
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G A I - T R O N I C S ® C O R P O R A T I O N
A H U B B E L L C O M P A N Y
Model 491-204
Mine Dial/Page Telephone
Confidentiality Notice
This manual is provided solely as an operational, installation, and maintenance guide and contains
sensitive business and technical information that is confidential and proprietary to GAI-Tronics. GAI-
Tronics retains all intellectual property and other rights in or to the information contained herein, and
such information may only be used in connection with the operation of your GAI-Tronics product or
system. This manual may not be disclosed in any form, in whole or in part, directly or indirectly, to any
third party.
General Information
The GAI-Tronics Mine Dial/Page Telephone system combines the convenience of a telephone station
with paging capabilities in gaseous or dusty locations too hazardous for standard telephone equipment.
The system is rated as “permissible” for use in gassy coal mines by the Mine Safety and Health
Administration (MSHA) of the United States Department of the Labor (Approval Number 9B-221).
The system is used in conjunction with a touch-tone (also known as dual-tone multi-frequency [DTMF])
operated public telephone exchange or a private branch exchange (PBX). Each station in the system is
made up of two components:
•
Mine Dial/Page Telephone
•
Interface assembly mounted outside the hazardous area
The interface assembly is electrically connected between the station and the telephone switchboard.
Each interface assembly is connected to a separate line of the telephone exchange.
Features
The GAI-Tronics Model 491-204 Mine Dial/Page Telephone system is designed as an alternative to the
mine pager system and other communication systems (such as the “Pager” or “Loud-Speaking
Telephone”) that lack privacy and multiple conversation capabilities. The GAI-Tronics Mine Dial/Page
Telephone system includes the following features:
•
Each station has a separate line. The number of independent, simultaneous conversations is limited
only by the number of stations and the capacity of the PBX.
•
Stations inside the hazardous area can call any telephone outside the area, as well as any other Mine
Dial/Page Telephone station within the area.
