[Code of Federal Regulations]

[Title 30, Volume 1]

[Revised as of July 1, 2006]

From the U.S. Government Printing Office via GPO Access

[CITE: 30CFR33.32]



[Page 167]

 

                       TITLE 30--MINERAL RESOURCES

 

  CHAPTER I--MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR

 

PART 33_DUST COLLECTORS FOR USE IN CONNECTION WITH ROCK DRILLING IN COAL 

MINES--Table of Contents

 

                       Subpart C_Test Requirements

 

Sec.  33.32  Determination of dust concentration.



    (a) Concentrations of airborne dust in the test space shall be 

determined by sampling with a midget impinger apparatus, and a light-

field microscopic technique shall be employed in determining 

concentrations of dust in terms of millions of particles (5 microns or 

less in diameter) per cubic foot of air sampled.

    (b) Before a drilling test is started the surfaces of the test space 

shall be wetted; the test space shall be cleared of air-borne dust 

insofar as practicable by mechanical ventilation or other means; and an 

atmospheric sample, designated as a control sample, shall be collected 

during a 5-minute period to determine residual airborne dust in the test 

space.

    (c) A sample of airborne dust, designated as a test sample, shall be 

collected in the breathing zone of the drill operators during the 

drilling of each test hole. Time consumed in changing drill steel shall 

not be considered as drilling time and sampling shall be discontinued 

during such periods.



[Sched. 25B, 25 FR 6473, July 9, 1960, as amended at 26 FR 2599, Mar. 

28, 1961]