TM8400B-L-00
1 November 2004
6.4. STANDARD OPERATING PRACTICES
These practices are recommended to ensure high standards of operation and thus optimize
instrument service life and/or improve instrument performance.
(a) When "flushing" - ensure FUNCTION switch is on STANDBY setting and not turned
back to READ until cell fills. Otherwise, electronics overloading may occur causing a
small temporary read offset requiring several minutes recovery time.
(b) When not using pumps - switch off to minimize pump maintenance and, if required, to
conserve sample water.
6.5. MEASURING FOR OPTIMAL ACCURACY
6.5.1. INSTRUMENT ACCURACY
The guarateed accuracy (±0.002 PSU) of this instrument makes allowance for some
variations in the ambient temperature as is readily achieved when the basic
standardization and operating procedures are followed. Performance to ±0.001 PSU or
less can be achieved with controlled conditions of the operating environment, the careful
handling of samples and refined instrument operating procedures.
6.5.2. PROCEDURAL REFINEMENTS
The following recommendations are provided as a guideline to the operator requiring
repeatable results to better than the instrument rated accuracy:
(a) Operate the instrument with the bath temperature set 1°C or 2°C above ambient
temperature. (The closer to ambient temperature, the better.) Temperature control
of the laboratory may be required if there are large time/temperature variations.
(b) Allow at least 24 hours for the bath to stabilize.
(c) Let the sample come to ambient temperature before using it (for nominal
accuracy, a lower flow rate will accommodate a wider temperature difference).
(d) If two or more instruments are to be standardized for agreement with each other,
fill all the cells with 35 PSU water before standardizing so that fewer flushes are
needed and that the same bottle of standard sea-water will suffice to standardize
all units.
(e) In general, once a cell has stabilized to the correct value, start reading after 5
seconds and visually average the readings for 10 to 15 seconds. The final average
reading should repeat for three consecutive flushes to within ±2 digits (i.e.
±0.0004 PSU at a salinity of 35 PSU).
To Next Page
Loading...