Product Overview

Chemical oxygen demand (COD) refers to the mass concentration of oxygen consumed by a strong oxidant under certain conditions when oxidizing organic and inorganic reducing substances in a water sample. COD is also an important indicator reflecting the degree of pollution of water bodies by organic and inorganic reducing substances.

This analytical instrument product is based on the water quality analysis and testing technology of Hong Kong Energy Company, developed and designed according to the national standard testing method "Water Quality - Determination of Chemical Oxygen Demand - Potassium Dichromate (GB11914-89)". It consists of a fluid dynamics unit, a visual photoelectric quantification unit, a flow path switching unit, a digestion measurement unit, and an embedded controller unit. It can quickly, accurately, continuously, and reliably complete the determination of COD in water bodies.

This analytical instrument is capable of long-term unmanned automatic continuous operation according to on-site settings, and is widely applicable to industrial pollution source discharge wastewater, industrial process wastewater, industrial sewage treatment plant wastewater, municipal sewage treatment plant wastewater, and other occasions. According to the complexity of the on-site testing conditions, corresponding preprocessing systems can be selected to ensure the reliability of the testing process, accurate testing results, and fully meet the on-site requirements of different occasions.

Basic Principles

The water sample, potassium dichromate digestion solution, mercury sulfate (mercury sulfate can eliminate the interference of chloride ions in water samples, as chloride ions can form very stable with mercury ions), and silver sulfate solution (silver sulfate can be added as a catalyst to more effectively oxidize linear fatty compounds) mixed solution are heated to 147 ℃. After the oxidation of organic matter in the solution by dichromate ions, the color will change. The analyzer detects this color change and converts it into COD value output. The amount of dichromate ions consumed is equivalent to the amount of oxidizable organic matter.

Technical Specifications

Method basis: National standard GB11914-89 "Water Quality - Determination of Chemical Oxygen Demand - Potassium Dichromate"

Measurement range: 4-50000 mg/L COD

Accuracy: When ≥ 100mg/L, not exceeding ± 10%; When<100mg/L, not exceeding ± 8mg/L

Repeatability: When ≥ 100mg/L, not exceeding ± 10%; When<100mg/L, not exceeding ± 6mg/L

Measurement cycle: The smallest measurement cycle is 40 minutes. According to the actual water sample, the digestion time can be modified arbitrarily within 5-120 minutes

Sampling period: time interval (adjustable from 40 to 9999 minutes) and whole point measurement mode

Calibration cycle: 1-99 days, adjustable at any interval and time

Maintenance cycle: usually once a month, about 30 minutes each time

Reagent consumption:Less than 0.35 yuan/sample

Output: RS-232

Environmental requirements: Indoor with adjustable temperature, recommended temperature range of+5-28 ℃; Humidity ≤ 90% (non condensing)

Power supply: AC230 ± 10% V, 50 ± 10% Hz,

Size: Height 1500 x Width 550 x Depth 450mm

Other: Abnormal alarms and power outages will not result in data loss; Touch screen display and command input