[Code of Federal Regulations]
[Title 40, Volume 18]
[Revised as of July 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR92.128]

[Page 460]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 92--CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES--
Table of Contents
 
                       Subpart B--Test Procedures
 
Sec. 92.128  Particulate handling and weighing.

    (a) At least 1 hour before the test, place each filter in a closed 
(to eliminate dust contamination) but unsealed (to permit humidity 
exchange) petri dish and place in a weighing chamber meeting the 
specifications of Sec. 92.110(a) of this section for stabilization.
    (b) At the end of the stabilization period, weigh each filter on the 
microbalance. This reading is the tare weight and must be recorded.
    (c) The filter shall then be stored in a covered petri dish or a 
sealed filter holder until needed for testing. If the filters are 
transported to a remote test location, the filter pairs, stored in 
individual petri dishes, should be transported in sealed plastic bags to 
prevent contamination. At the conclusion of a test run, the filters 
should be removed from the filter holder, and placed face to face in a 
covered but unsealed petri dish, with the primary filter placed face up 
in the dish. The filters shall be weighed as a pair. If the filters need 
to be transported from a remote test site, back to the weighing chamber, 
the petri dishes should be placed in a sealed plastic bag to prevent 
contamination. Care should be taken in transporting the used filters 
such that they are not exposed to excessive, sustained direct sunlight, 
or excessive handling.
    (d) After the emissions test, and after the sample and back-up 
filters have been returned to the weighing room after being used, they 
must be conditioned for at least 1 hour but not more than 80 hours and 
then weighed. This reading is the gross weight of the filter and must be 
recorded.
    (e) The net weight of each filter is its gross weight minus its tare 
weight. Should the sample on the filter contact the petri dish or any 
other surface, the test is void and must be rerun.
    (f) The particulate filter weight (Pf) is the sum of the net weight 
of the primary filter plus the net weight of the backup filter.
    (g) The following optional weighting procedure is permitted:
    (1) At the end of the stabilization period, weigh both the primary 
and back-up filters as a pair. This reading is the tare weight and must 
be recorded.
    (2) After the emissions test, in removing the filters from the 
filter holder, the back-up filter is inverted on top of the primary 
filter. They must then be conditioned in the weighing chamber for at 
least 1 hour but not more than 80 hours. The filters are then weighed as 
a pair. This reading is the gross weight of the filters (Pf) and must be 
recorded.
    (3) Paragraphs (a), (c), and (e) of this section apply to this 
option, except that the word ``filter'' is replaced by ``filters''.