Method 3 : Gas Analysis for the Determination of Dry Molecular Weight

This method pertains to the determination of CO2 and O2 concentrations and dry molecular weight of a sample from an effluent gas stream of a fossil-fuel combustion process or other process.

In this method, a gas sample is extracted from a stack by one of the following methods:

  • Single-point, grab sampling
  • Single-point, integrated sampling
  • Multi-point, integrated sampling

The gas sample is analyzed for percent CO2 and percent O2. For dry molecular weight determination, either an Orsat or a Fyrite analyzer may be used for the analysis.

The sampling apparatus required for this purpose must be capable of obtaining a representative sample and maintaining a constant sampling rate, and should be otherwise, capable of yielding acceptable results.

The required equipment is shown in the table below.

Type of sampling →
Equipment ↓
Grab sampling Integrated Sampling
Probe Stainless steel or borosilicate glass tubing equipped with an in-stack or out-of-stack filter to remove particulate matter (a plug of glass wool is satisfactory for this purpose).
Sampling Pump For transport the gas sample to the analyzer. A leak-free, diaphragm-type pump, or equivalent, to transport sample gas to the flexible bag. A small surge tank between the pump and rate meter needs to be installed to eliminate the pulsation effect of the diaphragm pump on the rate meter.
Flow Rate Meter Not required Range : A flow rate range of 500 to 1000 ml/min is suggested.
Accuracy : ±2 percent of the selected flow rate.
Flexible Bag - Any leak-free plastic : Tedlar, Mylar, Teflon or plastic-coated aluminum
Suggested capacity : 55 to 90 liters (1.9 to 3.2 ft3)
Leak rate : within specified limits
Pressure Meter - For flexible bag leak-check.
Vacuum Meter - For sampling train leak-check.
Combustion gas analyzer - Orsat or Fyrite type analyzer

We manufacture and / or supply all equipment required for implementation of Method 3 and much more.