[Code of Federal Regulations]
[Title 46, Volume 7]
[Revised as of October 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 46CFR197.340]

[Page 430]
 
                           TITLE 46--SHIPPING
 
   CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED)
 
PART 197--GENERAL PROVISIONS--Table of Contents
 
                 Subpart B--Commercial Diving Operations
 
Sec. 197.340  Breathing gas supply.

    (a) A primary breathing gas supply for surface-supplied diving must 
be sufficient to support the following for the duration of the planned 
dive:
    (1) The diver.
    (2) The standby diver.
    (3) The decompression chamber, when required by Sec. 197.432(e)(2) 
or by Sec. 197.434(a) for the duration of the dive and for one hour 
after completion of the planned dive.
    (4) A decompression chamber when provided but not required by this 
subpart.
    (5) A closed bell when provided or required by Sec. 197.434(d).
    (6) An open bell when provided or required by Sec. 197.432(e)(4) or 
by Sec. 197.434(c).
    (b) A secondary breathing gas supply for surface-supplied diving 
must be sufficient to support the following:
    (1) The diver while returning to the surface.
    (2) The diver during decompression.
    (3) The standby diver.
    (4) The decompression chamber when required by Sec. 197.432(e)(2) or 
by Sec. 197.434(a) for the duration of the dive and one hour after the 
completion of the planned dive.
    (5) The closed bell while returning the diver to the surface.
    (6) The open bell while returning the diver to the surface.
    (c) A diver-carried reserve breathing gas supply for surface-
supplied diving must be sufficient to allow the diver to--
    (1) Reach the surface.
    (2) Reach another source of breathing gas; or
    (3) Be reached by a standby diver equipped with another source of 
breathing gas for the diver.
    (d) A primary breathing gas supply for SCUBA diving must be 
sufficient to support the diver for the duration of the planned dive 
through his return to the dive location or planned pick-up point.
    (e) A diver-carried reserve breathing gas supply for SCUBA diving 
must be sufficient to allow the diver to return to the dive location or 
planned pick-up point from the greatest depth of the planned dive.
    (f) Oxygen used for breathing mixtures must--
    (1) Meet the requirements of Federal Specification BB-0-925a; and
    (2) Be type 1 (gaseous) grade A or B.
    (g) Nitrogen used for breathing mixtures must--
    (1) Meet the requirements of Federal Specification BB-N-411c;
    (2) Be type 1 (gaseous);
    (3) Be class 1 (oil free); and
    (4) Be grade A, B, or C.
    (h) Helium used for breathing mixtures must be grades A, B, or C 
produced by the Federal Government, or equivalent.
    (i) Compressed air used for breathing mixtures must--
    (1) Be 20 to 22 percent oxygen by volume;
    (2) Have no objectionable odor; and
    (3) Have no more than--
    (i) 1,000 parts per million of carbon dioxide;
    (ii) 20 parts per million carbon monoxide;
    (iii) 5 milligrams per cubic meter of solid and liquid particulates 
including oil; and
    (iv) 25 parts per million of hydrocarbons (includes methane and all 
other hydrocarbons expressed as methane).