Apparatus and methods for determining the concentration of black carbon particles in a combustion exhaust

A method of analyzing particles in a predetermined or measured volume of sample gas provided to an apparatus, said method comprising:

• purging the apparatus with a first flow background gas, where the apparatus includes a gas inlet, a filter configured to collect particles in a gas provided to the inlet, and an analyzer for measuring properties of the particles collected on the filter, where the purging is sufficient for the temperature of the filter and moisture on the filter to reach equilibrium values of temperature and moisture with the background gas;
• performing a first analytical measurement on the filter after providing the first flow of background gas;
• flowing the predetermined or measured volume of sample gas through the inlet, and then providing a second flow of background gas through the inlet, where the second flow is sufficient to displace the volume of sample gas through the filter and have the filter to reach equilibrium values of temperature and moisture with the background gas,
• performing a second analytical measurement on the filter after providing the second flow of background gas;
• and
• determining a measurement of particles in the sample gas from the first analytical measurement and the second analytical measurement.

An apparatus for batch analyzing a volume of sample gas for particles, said apparatus comprising:

• a probe adapted to accept the sample gas and a background gas;
• a gas holding volume to accept gas from the probe;
• an analyzer to accept gas from the gas holding volume, where the analyzer includes a filter to collect particles from the gas and perform measurements on the filter;
• a flow system to provide air flow from the probe to the filter;
• and
• electronics programmed to operate the apparatus to perform the method of:
• providing a first flow of background gas to the filter, where said first flow of background gas is sufficient to allow the filter to reach equilibrium values of temperature and moisture with the background gas;
• performing a first analytical measurement on the filter;
• flowing the predetermined or measured volume of sample gas through the filter, and thereafter providing a second flow of background gas to the filter, where said second flow is sufficient to allow the filter to reach equilibrium values of temperature and moisture with the background gas;
• performing a second analytical measurement on the filter after the flowing of the sample gas through the filter;
• and
• determining a measurement of particles in the sample gas from the first analytical measurement and the second analytical measurement.