Hover over areas of the diagram to see a detailed description.
The gas sample is drawn into the analyser via a sample probe and hose connected to the inlet on the side panel of the analyser.
The sample enters the Water Catchpot where it rapidly expands causing any residual water in the gas sample to drop into to the catchpot.
The gas sample leaves the Water Catchpot and passes through a particulate filter. The filter removes particles in the gas sample larger than 0.1μm.
The pressure sensor is used in conjunction with the flow probe to determine the gas flow rate and mass emissions levels.
The gas sample flow inside the analyser is controlled by a three way solenoid valve. When starting the analyser, the valve allows ambient air to be drawn through the system and performs a zero-calibration on the gas sensor cells before switching to sample flue gas. This arrangement allows the analyser to perform a zero calibration without the need to remove the sample probe from the duct.
The sample pump controls the flow of sample gas into the analyser.
On leaving the pump, the sample enters a series of flow restrictors and expansion chambers in order to remove pressure and flow variations from the sample.
To ensure that the CO and CxHy sensor cells are not poisoned by other components in the sample gas, the flow is routed through a chemical filter.
To protect the COLow sensor from high levels of carbon monoxide, normally exceeding 2000ppm, a dedicated purge pump is connected directly to the COLow sensor. When the analyser measures carbon monoxide levels greater than 2000ppm, the cell is purged with ambient air to protect the sensor and ensure optimum recovery time and maximised sensor life. Measurement of carbon monoxide is then performed by the COHigh sensor.
Exhaust from the manifold is then fed to a connector on the instrument side panel.
If a flow probe is used an additional input is provided such that the differential pressure can be measured enabling the duct flow to be calculated.