Measurement of dissolved oxygen by sensor method
The most popular method for measuring dissolved oxygen is to use dissolved oxygen gauges and sensors. Although the general categories of dissolved oxygen sensors are optical and electrochemical, electrochemical sensors can be further subdivided into polarography, pulse polarography, and current sensors. In addition to standard analog outputs, some of these DO sensor technologies can also be used in smart sensor platforms with digital outputs. Dissolved oxygen sensors can be used in the laboratory or in the field. DO sensors can be designed for use in biochemical oxygen demand (BOD) testing, field sampling, or long-term monitoring applications. A dissolved oxygen meter, water quality detector, or data recording system can be used to record measurements taken by the dissolved oxygen sensor.
Electrochemical DO sensor
Electrochemical dissolved oxygen sensors may also be called ampere-type or Clark type sensors. There are two types of electrochemical dissolved oxygen sensors: electroflow and polarography. Polarographic dissolved oxygen sensors can be further subdivided into steady-state and fast pulse sensors. Both galvanic cells and polarographic DO sensors use two polarized electrodes, an anode and a cathode, in electrolyte solution 7. The electrode and electrolyte solution are isolated from the sample by a thin semi-permeable membrane. When measurements are made, dissolved oxygen diffuses through the membrane at a rate proportional to the oxygen pressure in the water . The dissolved oxygen is then reduced and consumed at the cathode.
Dissolved Oxygen Meters
Portable dissolved oxygen analyzer (determinator) is mainly used in laboratories, aquariums, aquatic product breeding, rice fields, swimming pools, etc. It is specially designed for the convenience of users to carry to the scene. The portable dissolved oxygen analyzer can be divided into two parts: the sensor and the electronic unit. The sensor adopts a tube-type coated dissolved oxygen electrode. The electronic unit is composed of high integrated circuits. The instrument uses a liquid crystal display, which can actually measure the dissolved oxygen, temperature, salt content and other values.