YSI 9300 Photometer - Manual (Page 125)

PHOTOMETER TEST INSTRUCTIONS
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DISSOLVED OXYGEN/2
The presence of dissolved oxygen in water used in boilers and steam raising
plant is wholly undesirable. At high temperatures even small amounts of
dissolved oxygen render the water highly corrosive to boiler plant, the oxygen
must be removed from boiler feedwater by chemical treatment or by mechanical
de-aeration.
The DO/2.0 tests provide a simple means of testing for dissolved oxygen in
boiler water or boiler feedwater. The test covers the range and 0 - 2.0 mg/l.
Method
Special techniques must be employed when testing for dissolved oxygen as the
water sample can be readily contaminated by the oxygen in the atmosphere.
CHEMetrics Vacu-Vials self-filling reagent ampoules provide the ideal means of
carrying out this test. The tip of the ampoule is dipped into the water sample
and is then broken to allow the vial to fill with water. In this way there is no
possibility of contamination from the air.
The Vacu-Vial DO/2.0 test uses a reagent based on the indigo carmine method.
Indigo carmine, in its reduced form, reacts with dissolved oxygen to form a blue
complex.
The intensity of the colors formed in the tests is proportional to the dissolved
oxygen content of the water and is measured using a YSI Photometer.
Reagents and Equipment
DO Vial Set DO/2.0 (503)
YSI 9300 or 9500 Photometer
DO test reagents are light sensitive. Store tubes in original containers and keep
the box closed when not in use.
Photometer Method
AUTOMATIC
WAVELENGTH
SELECTION
0 – 2.0 mg/l
PHOT.50.AUTO