[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: 30CFR27.38]

[Page 146]
 
                       TITLE 30--MINERAL RESOURCES
 
  CHAPTER I--MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR
 
PART 27--METHANE-MONITORING SYSTEMS--Table of Contents
 
                      Subpart C--Test Requirements
 
Sec. 27.38  Tests to determine adequacy of windows and lenses.

    Impact tests. A 4-pound cylindrical weight with a one-inch diameter 
hemispherical striking surface will be dropped (free fall) to strike the 
window or lens in its mounting or the equivalent thereof at or near the 
center. At least three out of four samples shall withstand the impact 
according to the following table:

------------------------------------------------------------------------
                                                                 Height
                Overall lens diameter (inches)                   of fall
                                                                (inches)
------------------------------------------------------------------------
Less than 4...................................................         6
4 to 5........................................................         9
5 to 6........................................................        15
Greater than 6................................................        24
------------------------------------------------------------------------


Lenses or windows of smaller diameter than 1 inch may be tested by 
alternate methods at the discretion of MSHA.