EPA Method 15 - H2S in Fuel Gases



Method Overview

  • The sample is withdrawn directly from the source through heated line to the GC
  • Analysis is semi-continuous with a snapshot every 5-20 minutes
  • Method 15 requires a minimum of sixteen injections per test run
  • Sample degradation issues are minimized by direct injection into the GC
  • Direct injection is an excellent tool for tracking batch processes (unless the process changes can occur faster than the snapshot injection times)

Target Compounds

  • Dimethyl sulfide [(CH3)2S]
  • Dimethyl disulfide [(CH3)2S2]
  • Methyl mercaptan (CH4S)
  • Hydrogen sulfide (H2S)
  • Carbonyl sulfide (COS)
  • Carbon disulfide (CS2)
  • The lower range of this procedure is determined by the sampling system. This is generally about 0.5 ppmv.
  • The upper limit is governed by the GC detector saturation or column overloading. The upper range can be extended by dilution interface sampling.

Performance Tips

  • Sample is withdrawn from the source and delivered continuously to the GC (similar to EPA Method 25A). A preferred sampling rate would yield a response time of less than one minute.
  • All heated elements should be set to ~250oF;
  • A test run consists of a minimum of 16 sample injections over:
    • A minimum test time of three hours; and
    • A maximum test time of six hours.
    • Three test runs comprise a test series
  • A slip-stream of the sample is drawn through a gas sampling valve on the instrument;
    • An injection is performed by rotating the valve;
    • Each injection will typically require 5-20 minutes to perform the analysis.
  • A recovery study must be performed following sampling (similar to sample system bias);
    • Performed by introducing sample to the probe tip and sampling similar to stack gases;
    • Recovery is acceptable if bias is within +10% of the at-instrument value.
    • Analysis results are typically not corrected for this recovery study results
  • Short lengths of unheated lines can cause sample loss through condensation (e.g. 4" of teflon line). All sample delivery lines should be heated.

Shipping

  • No shipping issues - samples analyzed on-site.

Applications

  • An excellent method for determining possible emissions from combustion of a given gaseous fuel such as refinery flare gases, anaerobic fuel, and others.

Accreditation

  • None, please contact us if you have any questions!

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