E Instruments E500, User Manual

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4.0 DESCRIPTION OF THE PRODUCT
4.1 Working principle
The gas sample is taken in through the gas probe, by a diaphragm suction pump inside the instrument.
The measuring probe has a sliding cone that allows the probe to be inserted in holes with a diameter of 11 mm to
16 mm and to adjust the immersion depth: it is recommended to have a gas sampling point roughly in the
center of the flue/stack.
The gas sample is cleaned of humidity and impurities by a condensate trap and filter located inside the
instrument.
The gas is then analyzed in its components by electrochemical.
The electrochemical cell guarantees high precision results in a time interval of up to about 60 minutes during
which the instrument can be considered very stable.
When measurement is going to take a long time, we suggest auto-zeroing the instrument again and flushing the
inside of the pneumatic circuit with clean air.
During the zero calibrating phase, the instrument aspirates clean air from the environment and detects the cells’
drifts from zero (20.95% for the O2 cell), then compares them with the programmed values and compensates them.
4.2 Measurement cells
The instrument takes advantage of pre-calibrated gas sensors for the measurement of Oxygen (O2), Carbon
Monoxide (CO) and Nitric Oxide (NO) if available.
The sensors do not need particular maintenance yet they have to be replaced periodically when exhausted.
If sensors of toxic gases are submitted to concentrations higher than 50% of their measurement range for more
than 10 minutes continuously, they can show up to ±2% drift as well as a longer time to return to zero.
In this case, before turning off the analyzer, it is advisable to wait for the measured value be lower than 20ppm by
in taking clean air.
Anyway, the instrument is intended to have a cleaning cycle of the pneumatic circuit, which duration depends on
what has been set in the menu Configuration→Analysis→Autozero.
Exhausted cells can be easily replaced by the user without depriving himself of the instrument and without
complicated calibration procedures with certified mixtures as they are pre-calibrated before being supplied.
E instruments certifies the accuracy of the measurements only upon a calibration certificate issued by its
laboratory or other approved laboratory.
4.3 Fuel types
The device is provided with the technical data of the most common types of fuels stored in its memory.
For more details see Annex D.
4.4 Sample treatment
The gas sample to be analyzed must be delivered to the measuring sensors properly dried and cleaned of solid
residues of combustion; actually for this reason it is usually named ‘dry analysis’.
For this purpose, on the gas suction line, is mounted an anti-condensation trap with dust filter.
4.5 Pressure sensor, piezoelectric, temperature compensated
The instrument is internally provided with a piezoresistive differential pressure sensor which can be used for
measuring the draft (vacuum) in the stack for differential pressure measurement and possibly for other
measurements (pressure of gas in the piping, pressure loss across a filter, etc.).
The measurement range is -10.000 Pa .. +20.000 Pa.
Any potential drift of the sensor are nulled thanks to the autozeroing system.
4.6 Suction pump
This diaphragm pump, located inside the instrument, is operated with a DC engine powered by the instrument in
order to obtain the optimal suction flow rate of the flue gas for the ongoing analysis.
4.7 Draft measurement with sensor automatic autozero
E500 performs the draft measurement.
The sensor Autozero allows to make the zeroing of the sensor and must be done with the gas probe NOT
inserted in the stack.
WARNING
ANY PRESSURE APPLIED TO THE SENSOR GREATER THAN ± 300 hPa MAY CAUSE A
PERMANENT DEFORMATION OF THE MEMBRANE, THUS DAMAGING IRREVERSIBLY THE
SENSOR ITSELF.