Analytical · Glossary

What is Dissolved Oxygen?

Symbol: DOmg/L or % saturationAnalytical

Dissolved oxygen is the amount of oxygen gas dissolved in water, measured in mg/L or as % of saturation.

Dissolved Oxygen Explained

DO control saves energy in aeration basins and protects fish and boilers. Optical (luminescent) sensors are now common; galvanic and polarographic membrane sensors are older types.

Saturation falls with temperature, salinity and altitude.

Dissolved Oxygen: Typical Values

Saturation at 20 °C, sea level, fresh water	about 9.09 mg/L
Saturation at 25 °C	about 8.26 mg/L
Aeration basin control	often about 1.5 to 2 mg/L

Calculators for Dissolved Oxygen

CalculatorDissolved Oxygen Saturation CalculatorFree online calculator with formula and worked example.

Frequently Asked Questions

What is Dissolved Oxygen?

Dissolved oxygen is the amount of oxygen gas dissolved in water, measured in mg/L or as % of saturation.

How is a DO sensor calibrated?

Usually in water saturated air at known pressure, sometimes with a zero solution.

Why is optical DO popular?

No membrane or electrolyte to change and low drift.

Learn more on the blog

Electrical conductivity explained

A practical guide on instrumentationblog.in with more detail on dissolved oxygen and how it is applied on real plants.

Read Full Article

More Analytical Terms

Analytical termWater HardnessWater hardness is the concentration of calcium and magnesium in water, usually expressed as mg/L of…Analytical termppm to mg/m³ Conversionppm to mg/m³ conversion turns a gas concentration by volume into mass per volume, using the molar mass…Analytical termLower Explosive LimitLower explosive limit is the lowest concentration of a flammable gas in air that can ignite; below it the…Analytical termSpan GasSpan gas is a certified gas mixture with a known concentration, used to set the upper calibration point…Analytical termExcess AirExcess air is the air supplied to a burner beyond the theoretical amount needed for complete combustion.Analytical termEmission Oxygen CorrectionEmission oxygen correction converts a measured pollutant concentration to a reference oxygen level, so…

All analytical terms · Full glossary A to Z