[Code of Federal Regulations]
[Title 30, Volume 1]
[Revised as of July 1, 2002]
From the U.S. Government Printing Office via GPO Access
[CITE: 30CFR23.8]

[Page 138]
 
                       TITLE 30--MINERAL RESOURCES
 
  CHAPTER I--MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR
 
PART 23--TELEPHONES AND SIGNALING DEVICES--Table of Contents
 
Sec. 23.8  Inspection and tests.

    (a) A thorough inspection of the telephone or signaling device will 
be made to determine its adequacy and permisibility. Tests may be made 
to check the electrical characteristics and constants of the various 
parts, and determine the adequacy of the insulation and other parts of 
features of the device.
    (b) In addition, compartments of explosion-proof design will be 
tested while filled and surrounded with explosive mixtures containing 
varying percentages of Pittsburgh natural gas 2 and air, the 
mixture within the compartment being ignited by a spark plug or other 
suitable means. For some of the tests bituminous-coal dust will be 
introduced into the compartment in addition to the explosive mixtures, 
and the effects will be noted. A sufficient number of tests will be made 
under the foregoing conditions to determine the ability of the 
compartment to retain flame without bursting. Even though the 
surrounding mixtures are not ignited, the compartment will not be 
considered as having passed the tests, if flames are discharged from any 
joint or opening; if excessive pressures are developed or if serious 
distortion of the compartment walls take place.
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     2  Investigation has shown that for test purposes 
Pittsburgh natural gas (containing a high percentage of methane) is a 
satisfactory substitute for pure methane.
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