Hanna Instruments HI 4105, Инструкция по эксплуатации

Страница: 7 / 20

7
VII VII VII VII VII. General Guidelines General Guidelines General Guidelines General Guidelines General Guidelines
•
Calibration standards and sample solutions should
have the same ionic strength. ISA should be added to
both samples and standards immediately before tak-
ing measurements.
•
Calibration standards and sample solutions should be
stirred at the same rate using identical sized stir bars.
Stir thoroughly and continuously.
•
Calibration standards and sample solutions should be
at the same temperature. Thermally insulate solution
vessel from magnetic stirrer with cork or other insulat-
ing medium.
•
Wait until sensor value has stabilized before taking
reading (at least 5 minutes when going from more
dilute to more concentrated samples, longer when the
order is reversed).
•
Surface coating on the PTFE membrane will effect the
response. Inspect sensor before using. Wash off with a
jet of deionized water or mild detergent to remove
film.
•
Replace PTFE membrane if damage is evident or a
droplet of internal electrolyte is seen.
•
Rinse electrode with distilled or deionized water be-
tween samples and dab dry with lab wipe or other soft
disposable absorbent toweling.
•
Check calibration every 1-2 hours. Recalibrate if nec-
essary.
•
Position sensors at an angle of approximately 20
°
to
30
°
from verticle to reduce possibility of trapping gas
bubbles on on the membrane cap. Gas bubbles also
form from solution out-gassing due to temperature
change. Gently tap body of sensor to dislodge them.
•
Close container with plastic wrap or use HI 4000-71
gas sensor test vessel to prevent gas from leaving.
•
If electrode was left out in air for a prolonged period,
gently pulling cable will permit an exchange of fill
solution at the membrane surface. Re-Calibration is
required.