39
Applications
Oxygen is essential for f sh, invertebrate, plant, and aerobic bacteria
respiration. DO levels below 3 ppm are stressful to most aquatic
organisms. Levels below 2 or 1 ppm will not support f sh. Fish growth
and activity usually require 5 to 6 ppm of DO, an important consideration
for the aquaculture industry.
Low DO indicates a demand on the oxygen of the system. Natural
organic materials, such as leaves, accumulate in the stream and create
an oxygen demand as they decompose. Organic materials from human
activities also create an oxygen demand in the system. Micro-organisms
consume oxygen as they decompose sewage, urban and agricultural
run-off, and discharge from food-processing plants, meat-packing plants
and dairies. There is an optimum DO level for this process and if the
DO level falls too low, the micro-organisms die and the decomposition
ceases. If the DO level is too high, more power is used than necessary for
aeration and the process becomes costly.
In boiler water applications, the presence of oxygen in the water will
increase corrosion and contribute to boiler scale that inhibits heat
transfer. In such instances it is critical to keep the DO concentration to a
minimum.
Some pollutants such as acid mine drainage produce direct chemical
demands on oxygen in the water. DO is consumed in the oxidation-
reduction reactions of introduced chemical compounds such as nitrate
(NO
3
1-
) and ammonia (NH
4
1+
), sulfate (SO
4
2-
), and sulf te (SO
3
2-
) and
ferrous (Fe
2+
) and ferric (Fe
3+
) ions.
These are important consideration for water and wastewater treatment
industry.
13. WARRANTY
LaMotte Company warrants this instrument to be free of defects in parts
and workmanship for 3 years from the date of shipment and the probe
to be free of defects in parts and workmanship for 6 months from the
date of shipment. The sender is responsible for shipping charges, freight,
insurance and proper packaging to prevent damage in transit. This
warranty does not apply to defects resulting from action of the user such
as misuse, improper wiring, operation outside of specif cation, improper
maintenance or repair, or unauthorized modif cation. LaMotte Company
