ECOPROBE 5 - rs dynamics

PID detection generally requires a more detailed description to understand its principle, calibration and
interpretation that what is offered in this text.
PID SELECTIVITY
ECOPROBE 5 PID analyzer is calibrated only for one calibration gas – Isobutene (Isobuthylene).
A PID analyzer does not provide a selective analysis of a given contaminant, but measures total
concentration of presented volatile organic compounds (VOC) and other toxic gases including chlorinated
hydrocarbons.
How can we understand the fact that there are more than 200 calibration compounds stored in the
instrument’s memory?
The user must first determine the identity of the measured compound, or the compound that is dominant in
the measured chemical. Once the compound is identified, the PID sensitivity can be adjusted to that
compound by selecting it from the list installed in ECOPROBE 5 in the “Configuration file” . The resulting
reading will show the total concentration of VOC, but with respect to the selected dominant compound, and
will be therefore close to the quantitative value.
Example: If Isobutene is selected in ECOPROBE 5 which is being used to measure a benzene leak of one
ppm, the PID will display two ppm because it is twice as sensitive to benzene as it is to Isobutene. Once we
have identified the compound as benzene, then the PID scale can be set to benzene and the PID will
accurately read one ppm if exposed to one ppm of benzene.
Unknown contaminant
The main task of a general field survey is fast mapping, monitoring and delineating of contaminated areas,
and identifying the contaminant sources and paths. When approaching an unknown chemical release, set
the PID to Isobutene as its calibration gas. The measured values will be relative but proportional to the
contaminant concentration over the surveyed area and will provide the operator with a map of the
contaminant plume, its source and its migration route.
Single-compound contaminant
Imagine the simplest situation when the contaminant consists of one known compound only. If you select it
from the list of calibration compounds in the “Configuration file” you will get an accurate concentration of the
single-compound contaminant.
Gas Mixture Detection
PID ANALYZER
Commonly a contaminant is a complex mixture of various compounds. The measured values provide
information about the total concentration of the contaminant, but not about the separate compounds.
In the case of a common hydrocarbon contaminant, e.g. a petroleum product, the operator can select one of
the hydrocarbon mixtures, e.g. diesel fuel, jet fuel, etc., from the list of measured compounds. The results
are close to quantitative values.
In case you need to be sure about the contaminant composition, it is recommended to have a sample
analyzed by a laboratory. From the results, select the most prevalent chemical compound from the list
provided by ECOPROBE 5. The measured data will be more precise and closer to the quantitative values.
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