Hach ORBISPHERE 51 Series User Manual page 56

Interferences configuration
These options are available to take into account the influence of some components or gases in the
sample during measurement. All available interference corrections are disabled by default.
The following interference corrections are available:
• For oxygen measurements - Salt
• For hydrogen measurements - Temperature, H
• For nitrogen measurements - Temperature, H
Note: If you believe you need to enable any of the above, it is advisable to contact a Hach Service
Representative first.
Oxygen interference configuration
These options are available to take into account the influence of some components or
gases in the sample during measurement. All available interference corrections are disabled
by default.
• Select Chlorinity, Salt or disabled. For chlorinity or salt, it is required to enter the actual
concentration in sample.
Interferences in hydrogen measurement
The presence of oxygen in the sample can have an effect on the hydrogen sensor to varying
degrees, depending on the membrane being used.
• Temperature compensation: If there is a significant fluctuation in the sample temperature
enable temperature compensation to reduce the influence of these temperature fluctuations.
• Interfering H2O: This only applies to measurements taken in 100% humid gases or in traces of
dissolved gas in water. It allows a correction to the slope and temperature coefficients calculated
during calibration.
The instrument can also compensate for the presence of helium in the sample. Note the default
helium interference is zero, hence must be calibrated in the calibration menu prior to enabling either
method below.
• Interfering He constant: Use if a method is available to remove all the H
hence isolate only the helium in the sample to be measured. This offset is determined in
calibration menu under interferences.
• Interfering He: If the sample contains a known concentration of helium, check this box and enter:
• %Vbar or %Vext: When the Medium setting of the measurement configuration is set to Gas
phase, enter the concentration of helium in the percentage of the partial pressure (or the
percentage of external pressure when enabled).
• [measurement unit] + temperature: When the Medium setting of the measurement
configuration is set to Liquid phase, enter the temperature of the solution and the helium
concentration with the same value and unit has the hydrogen measurement shown in the
display.
Interferences in nitrogen measurement
The presence of oxygen in the sample affects the nitrogen sensor. Oxygen produces about three
times the effect of an equivalent amount of nitrogen in a TC sensor causing a comparably erroneous
displayed value. For example, a properly calibrated nitrogen sensor, placed in air having 80%
nitrogen and 20% oxygen would, uncorrected, display approximately 140% nitrogen (80% + 3*20%).
• Temperature compensation: If there is a significant fluctuation in the sample temperature
enable temperature compensation to reduce the influence of these temperature fluctuations.
• Interfering H2O: This only applies to measurements taken in 100% humid gases or in traces of
dissolved gas in water. It allows a correction to the slope and temperature coefficients calculated
during calibration.
Measurement Menu
O, He
2
O
2
, like recombination,
2
55