ECOPROBE 5 - rs dynamics

HOW CAN WE UNDERSTAND AND INTERPRET THE RESULTS FROM THE IR METHANE AND IR
TOTAL PETROLEUM CHANNELS?
Both IR Methane and IR Total Petroleum channels are calibrated for methane.The results of the IR methane
channel corresponds exactly with the actual methane concentration.
Results of IR Total petroleum channel:
1. If only methane is present and no other hydrocarbons, the results of the methane channel and the
IR Total Petroleum channel show the actual amount of methane.
2. If a mixture of methane and other hydrocarbons is present, the IR Total Petroleum channel measures
the amount of petroleum hydrocarbons and methane. This value is higher than the result recorded by the
methane channel.
3. If only hydrocarbons are present and no methane – there is no reading on the methane channel, the
IR Total Petroleum channel measures the total amount of petroleum hydrocarbons. It is necessary to
take into account that this channel is calibrated for methane and that the measured value does not
reflect the precise quantity of hydrocarbon present. The resulting value is generally 6 – 10
times higher than the actual concentration of hydrocarbons. You can map the area in a relative way or
divide the results approximately by 10. Compare the IR TP value with the PID value at a station
where methane is not present. Ensure that the TP concentration is not above the photo-ionization
breakdown limit.
Since the IR TP channel is calibrated for methane and the PID analyzer analyzer
on Isobutene, you will never get the
same quantitative data from both analyzers. Reading of IR Total Petroleum channel may be 6 - 10 times
higher than the reading of the PID analyzer, calibrated on Isobutylene (see previous paragraph and
previous page). To obtain comparative readings from IR TP channel and PID channel, both analyzers
should be calibrated for the same gas!
Important Note:
IR ANALYZER
For the interpretation of soil vapor data it is essential that all available and relevant information
regarding the surveyed terrain is taken into consideration. The most important information
required, comprises inter alia general geology, the local soil profile, soil characteristics,
hydrogeological conditions, site history, dates of spillages, the type and volume(s) of the
contaminant(s) involved, etc. Without these contributions, an interpretation of ECOPROBE 5
data may be flawed.
71