GAI-Tronics 491-204 Manual

Pub. 42004-195E 

GAI-Tronics Corporation  400 E. Wyomissing Ave.  Mohnton, PA  19540  USA 

610-777-1374  

  800-492-1212  

  Fax:  610-796-5954 

V

ISIT WWW

.

GAI

-

TRONICS

.

COM FOR PRODUCT LITERATURE AND MANUALS

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.