Hach-Lange ORBISPHERE Model 51x User Manual - Manual (Page 54)

52
Measurement Menu
6.1 Instrument configuration
TPO or TPA calculation (portable instrument)
The TPO (Total Package Oxygen) and TPA (Total Package Air) features are available on the portable
instrument for an EC sensor measuring oxygen (refer also to the table in
Generic terms and definitions
on page 111 for an explanation of these two terms).
To initiate these options, the instrument must be configured in “Sample mode” (see TPO and TPA
parameters (portable instrument) below) and the TPO or TPA calculation must be enabled (see Advanced
configuration - EC sensor on page 55 ).
The operator also needs to ensure the package is shaken for about 5 minutes before measuring, and to
know the total volume of the package and the total volume of the contents of the package.
Continuous mode or sample mode (portable instrument)
Continuous mode is typically used for process measurement, whereas sample mode is aimed at lab
measurements of small volume individual samples such as cans, bottles, etc. The measurement mode is
a parameter defined for the entire instrument, not for each channel.
Continuous mode cycle
• Every 2 sec. measurements are refreshed on the display
• The relays and the analog outputs are updated
• Measurements are continuously stored in memory (volatile and non volatile memory) according to
individual settings
Sample mode cycle (portable instruments)
When the user wants to measure a sample:
•
He prepares the sample
• He starts the measurement
• Measurement is stopped when all active channels have reached their "stop criteria" (defined in the
channel configuration screen - see details in
Stop criteria configuration (portable instrument) on
page 53 ). The measurement value is stored according to individual settings. If the channel is
configured for TPO or TPA calculation the user must enter the respective parameters (see TPO and
TPA parameters (portable instrument) on page 53 )
• The user can then start a new measurement
Continuous or sample mode selection
• Select Measurement mode:
•
Continuous mode for on line process
• Sample mode for lab sample analysis (portable instruments only)
• Selection of units for barometric, external pressure and temperature
Sample mode measurements (portable instrument)
When the numeric view is selected, the normal measurement window is displayed. Press the function
key
(on the header bar) to initiate the sample measurement.
The text "In progress" and the measurement value are displayed sequentially. The measurement
process stops when the stop criteria selected are fulfilled. See
Stop criteria configuration (portable
instrument) on page 53
The measurement process is stopped when:
•
The "stop criteria" is fulfilled, typically when the gas concentration reaches the set threshold
• The function key has been pressed
• The "Maximum time" criteria is reached
• An error has occurred (e.g. sensor out)
When the sample measurement stops because the stop criteria are fulfilled, the gas concentration and
temperature are no longer refreshed. They indicate the measurement when the stop criteria was
reached. If the channel was configured for TPO or TPA calculation, enter the parameters (see
TPO and
TPA parameters (portable instrument) on page 53 ).
Note: The mini graph is continuously refreshed.
If the sample mode is stopped for another reason (user abort, max. time, or measurement error), the
“aborted” message is displayed. The reason for the stop is explained when the icon
is pressed (as
with any event).