[Code of Federal Regulations]
[Title 40, Volume 31]
[Revised as of July 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR1065.195]

[Page 699-700]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 1065_ENGINE-TESTING PROCEDURES--Table of Contents
 
                   Subpart B_Equipment Specifications
 
Sec.  1065.195  PM-stabilization environment for in-situ analyzers.

    (a) This section describes the environment required to determine PM 
in-situ. For in-situ analyzers, such as an inertial balance, this is the 
environment within a PM sampling system that surrounds the PM sample 
media. This is typically a very small volume.
    (b) Maintain the environment free of ambient contaminants, such as 
dust, aerosols, or semi-volatile material that could contaminate PM 
samples. Filter all air used for stabilization with HEPA filters. Ensure 
that HEPA filters are installed properly so that background PM does not 
leak past the HEPA filters.
    (c) Maintain the following thermodynamic conditions within the 
environment before measuring PM:
    (1) Ambient temperature. Select a nominal ambient temperature, Tamb, 
between (42 and 52) [deg]C. Maintain the ambient temperature within 
1.0 [deg]C of the selected nominal value.
    (2) Dewpoint. Select a dewpoint, Tdew, that corresponds to Tamb such 
that Tdew = (0.95Tamb-11.40) [deg]C. The resulting dewpoint will control 
the amount of water associated with sulfuric acid 
(H2SO4) PM, such that 1.1368 grams of water will 
be associated with each gram of H2SO4. For 
example, if you select a nominal ambient temperature of 47 [deg]C, set a 
dewpoint of 33.3 [deg]C.
    (3) Dewpoint tolerance. If the expected fraction of sulfuric acid in 
PM is unknown, we recommend controlling dewpoint within 1.0 [deg]C. This would limit any dewpoint-related change 
in PM to less than 2%, even for PM that is 50% 
sulfuric acid. If you know your expected fraction of sulfuric acid in 
PM, we recommend that you select an appropriate dewpoint tolerance for 
showing compliance with emission standards using Table 1 of Sec.  
1065.190 as a guide:
    (4) Absolute pressure. Maintain an absolute pressure of (80.000 to 
103.325) kPa. Use good engineering judgment to maintain a more stringent 
tolerance of absolute pressure if your PM measurement instrument 
requires it.
    (d) Continuously measure dewpoint, temperature, and pressure using 
measurement instruments that meet the PM-stabilization environment 
specifications in subpart C of this part. Use these values to determine 
if the in-situ stabilization environment is within the tolerances 
specified in paragraph (c) of this section. Do not use any PM quantities 
that are recorded when any of these parameters exceed the applicable 
tolerances.
    (e) If you use an inertial PM balance, we recommend that you install 
it as follows:
    (1) Isolate the balance from any external noise and vibration that 
is within a frequency range that could affect the balance.
    (2) Follow the balance manufacturer's specifications.
    (f) If static electricity affects an inertial balance, you may use a 
static neutralizer, as follows:
    (1) You may use a radioactive neutralizer such as a Polonium 
(\210\Po)

[[Page 700]]

source or a Krypton (\85\Kr) source. Replace radioactive sources at the 
intervals recommended by the neutralizer manufacturer.
    (2) You may use other neutralizers, such as a corona-discharge 
ionizer. If you use a corona-discharge ionizer, we recommend that you 
monitor it for neutral net charge according to the ionizer 
manufacturer's recommendations.