LANDTEC BIOGAS 3000, Руководство по эксплуатации, Страница: 172 / 181

172 Operating Manual
Problem Solving
OMBG3000 – Iss.01 © Copyright 2016
effect on the span is significant, see point B on Graph 1 - User calibration
explained .

Note: To perform an accurate user calibration it is critical that a good
user zero has been performed. LANDTEC recommends that this be done
with nitrogen in order to guarantee that none of the gas of interest is
present.

Note: To obtain a good zero it may be necessary to flow nitrogen for
several minutes, especially if the BIOGAS 3000 system has been subjected
to high levels of gas previously, in order to ensure there are no remains of
the target gas present. On the BIOGAS 3000, this would result in leaving
the system for several minutes before pressing ‘check’ during the gas
check process.
User Span Calibration
9.10.4
A span calibration is used to optimize the analyser at the span calibration
concentration (see point C on
Graph 1 - User calibration explained ) for the
current operational conditions. It corrects the span point but leaves the zero
unadjusted (this will be left at the last user zero if this has been performed)
and should be done at the concentration of interest in the particular
application.
If the user zero is poor and the span calibration is good, it will correct the gas
curve for the point of interest, but other points on the curve could be
incorrect, see curve 3 on
Graph 1 - User calibration explained .
Trouble Shooting
9.10.5
9.10.5.1 User Zero Calibration Failed
Three possible reasons for this are that:

The BIOGAS 3000 module is trying to zero to a level which is outside the
predetermined range set when the module was last factory calibrated

The gas is not stable i.e. it is still purging out the measured gas

The system is not seeing a flow of gas.