[Code of Federal Regulations]
[Title 40, Volume 30]
[Revised as of July 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR1065.250]
[Page 662-663]
TITLE 40--PROTECTION OF ENVIRONMENT
CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
PART 1065_TEST PROCEDURES AND EQUIPMENT--Table of Contents
Subpart C_Test Fuels and Analytical Gases
Sec. 1065.250 Analytical gases.
Analytical gases that you use to comply with this part must meet the
accuracy and purity specifications of this section. You must record the
expiration date specified by the gas supplier and may not use any gas
after the expiration date.
(a) Pure gases. Use the ``pure gases'' shown in the following table:
Table 1 of Sec. 1065.250--Concentration Limits for Pure Gases
--------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum contaminant concentrations
Gas type ------------------------------------------------------------------------------------------- Oxygen content
Organic carbon Carbon monoxide Carbon dioxide Nitric oxide (NO)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Purified Nitrogen................. 1 ppmC............... 1 ppm................ 400 ppm.............. 0.1 ppm............. NA.
-----------------------------------
Purified Oxygen................... NA................... NA................... NA................... NA.................. 99.5-100.0%.
-----------------------------------
Purified Synthetic Air, or Zero- 1 ppmC............... 1 ppm................ 400 ppm.............. 0.1 ppm............. 18-21%.
Grade Air.
--------------------------------------------------------------------------------------------------------------------------------------------------------
(b) Fuel for flame ionization detectors. Use a hydrogen-helium
mixture as the fuel. Make sure the mixture contains 40 2 percent hydrogen and no more than 1 ppmC of organic
carbon or 400 ppm of CO2.
(c) Calibration and span gases. Apply the following provisions to
calibration and span gases:
(1) Use the following gas mixtures, as applicable, for calibrating
and spanning your analytical instruments:
(i) Propane in purified synthetic air. You may ask us to allow you
to use propane in purified nitrogen for high concentrations of propane.
(ii) CO in purified nitrogen.
[[Page 663]]
(iii) NO and NO2 in purified nitrogen (the amount of
NO2 in this calibration gas must not exceed 5 percent of the
NO content).
(iv) Oxygen in purified nitrogen.
(v) CO2 in purified nitrogen.
(vi) Methane in purified synthetic air.
(2) The calibration gases in paragraph (c)(1) of this section must
be traceable to within one percent of NIST gas standards or other gas
standards we have approved. Span gases in paragraph (c)(1) of this
section must be accurate to within two percent of true concentration,
where true concentration refers to NIST gas standards, or other gas
standards we have approved. Record concentrations of calibration gas as
volume percent or volume ppm.
(3) You may use gases for species other than those in paragraph
(c)(1) of this section (such as methanol in air gases used to determine
response factors), as long as they meet the following criteria:
(i) They are traceable to within 2 percent of
NIST gas standards or other standards we have approved.
(ii) They remain within 2 percent of the
labeled concentration. Show this by measuring quarterly with a precision
of 2 percent (two standard deviations) or by using
another method we approve. You may take multiple measurements. If the
true concentration of the gas changes by more than two percent, but less
than ten percent, you may relabel the gas with the new concentration.
(4) You may generate calibration and span gases using precision
blending devices (gas dividers) to dilute gases with purified nitrogen
or with purified synthetic air. Make sure the mixing device produces a
concentration of blended calibration gases that is accurate to within
1.5 percent. To do so, you must know the
concentration of primary gases used for blending to an accuracy of at
least 1 percent, traceable to NIST gas standards
or other gas standards we have approved. For each calibration
incorporating a blending device, verify the blending accuracy between 15
and 50 percent of full scale. You may optionally check the blending
device with an instrument that is linear by nature (for example, using
NO gas with a CLD). Adjust the instrument's span value with the span gas
connected directly to it. Check the blending device at the used settings
to ensure that the difference between nominal values and measured
concentrations at each point stays within 0.5
percent of the nominal value.
(d) Oxygen interference gases. Gases to check oxygen interference
are mixtures of oxygen, nitrogen, and propane. The oxygen concentration
must be 20-22 percent and the propane concentration must be 50-90
percent of the maximum value in the most typically used FID range.
Independently measure the concentration of total hydrocarbons plus
impurities by chromatographic analysis or by dynamic blending.