[Code of Federal Regulations]
[Title 40, Volume 31]
[Revised as of July 1, 2006]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR1065.190]
[Page 696-698]
TITLE 40--PROTECTION OF ENVIRONMENT
CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
PART 1065_ENGINE-TESTING PROCEDURES--Table of Contents
Subpart B_Equipment Specifications
Sec. 1065.190 PM-stabilization and weighing environments for
gravimetric analysis.
(a) This section describes the two environments required to
stabilize and weigh PM for gravimetric analysis: the PM stabilization
environment, where filters are stored before weighing; and the weighing
environment, where the balance is located. The two environments may
share a common space.
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These volumes may be one or more rooms, or they may be much smaller,
such as a glove box or an automated weighing system consisting of one or
more countertop-sized environments.
(b) We recommend that you keep both the stabilization and the
weighing environments free of ambient contaminants, such as dust,
aerosols, or semi-volatile material that could contaminate PM samples.
We recommend that these environments conform with an ``as-built'' Class
Six clean room specification according to ISO 14644-1 (incorporated by
reference in Sec. 1065.1010); however, we also recommend that you
deviate from ISO 14644-1 as necessary to minimize air motion that might
affect weighing. We recommend maximum air-supply and air-return
velocities of 0.05 m/s in the weighing environment.
(c) Verify the cleanliness of the PM-stabilization environment using
reference filters, as described in Sec. 1065.390(b).
(d) Maintain the following ambient conditions within the two
environments during all stabilization and weighing:
(1) Ambient temperature and tolerances. Maintain the weighing
environment at a tolerance of (22 1) [deg]C. If
the two environments share a common space, maintain both environments at
a tolerance of (22 1) [deg]C. If they are
separate, maintain the stabilization environment at a tolerance of (22
3) [deg]C.
(2) Dewpoint. Maintain a dewpoint of 9.5 [deg]C in both
environments. This 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.
(3) Dewpoint tolerances. If the expected fraction of sulfuric acid
in PM is unknown, we recommend controlling dewpoint at within 1 [deg]C tolerance. 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
the following table as a guide:
Table 1 of Sec. 1065.190--Dewpoint Tolerance as a Function of % PM Change and % Sulfuric Acid PM
----------------------------------------------------------------------------------------------------------------
0.5% PM mass change eq>1.0% PM mass change eq>2.0% PM mass change
of PM (percent)
----------------------------------------------------------------------------------------------------------------
5................................ 3.0 12
[deg]C. eq>6.0 [deg]C. [deg]C
50............................... 0.30 [deg]C. eq>0.60 [deg]C. eq>1.2 [deg]C
100.............................. 0.15 [deg]C. eq>0.30 [deg]C. eq>0.60 [deg]C
----------------------------------------------------------------------------------------------------------------
(e) Verify the following ambient conditions using measurement
instruments that meet the specifications in subpart C of this part:
(1) Continuously measure dewpoint and ambient temperature. Use these
values to determine if the stabilization and weighing environments have
remained within the tolerances specified in paragraph (d) of this
section for at least the past 60 min. We recommend that you provide an
interlock that automatically prevents the balance from reporting values
if either of the environments have not been within the applicable
tolerances for the past 60 min.
(2) Continuously measure atmospheric pressure within the weighing
environment. You may use a shared atmospheric pressure meter as long as
you can show that your equipment for handling the weighing environment
air maintains ambient pressure at the balance within 100 Pa of the shared atmospheric pressure. Provide a
means to record the most recent atmospheric pressure when you weigh each
PM sample. Use this value to calculate the PM buoyancy correction in
Sec. 1065.690.
(f) We recommend that you install a balance as follows:
(1) Install the balance on a vibration-isolation platform to isolate
it from external noise and vibration.
(2) Shield the balance from convective airflow with a static-
dissipating draft shield that is electrically grounded.
(3) Follow the balance manufacturer's specifications for all
preventive maintenance.
(4) Operate the balance manually or as part of an automated weighing
system.
(g) Minimize static electric charge in the balance environment, as
follows:
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(1) Electrically ground the balance.
(2) Use 300 series stainless steel tweezers if PM samples must be
handled manually.
(3) Ground tweezers with a grounding strap, or provide a grounding
strap for the operator such that the grounding strap shares a common
ground with the balance. Make sure grounding straps have an appropriate
resistor to protect operators from accidental shock.
(4) Provide a static-electricity neutralizer that is electrically
grounded in common with the balance to remove static charge from PM
samples, as follows:
(i) You may use radioactive neutralizers such as a Polonium
(\210\Po) source. Replace radioactive sources at the intervals
recommended by the neutralizer manufacturer.
(ii) You may use other neutralizers, such as corona-discharge
ionizers. If you use a corona-discharge ionizer, we recommend that you
monitor it for neutral net charge according to the ionizer
manufacturer's recommendations.
(5) We recommend that you use a device to monitor the static charge
of PM sample media surfaces.
(6) We recommend that you neutralize PM sample media to within
2.0 V of neutral.