Equipment configuration for simultaneous digestion of up to 6 or 12 COD samples according to EN/DEV and ISO 6060. Systems consist of the following components:

• Microprocessor-controlled TRS 300 time/temperature regulator with COD program
• Precision heating block CSB/E for RG2 vessels
• Holding frame E/B for RG2 sample vessels
• Cooling bath KW/N with mounting for E/B frame
• Sample vessels RG 2
• Air-cooled condensers LK 1
• Condenser stand LS for LK condensers

Complete workstations for simultaneous determination of up to 6 or 12 COD samples according to EN/DEV and ISO 6060. Manual reagent addition and titration.
A workstation consists of the following:

• Microprocessor-controlled TRS 300 time/temperature regulator with COD program
• Precision heating block CSB/E for RG 2 vessels
• Holding frame E/B for RG 2 sample vessels
• Cooling bath KW/N with mounting for E/B frame
• Multi-position magnetic stirrer SM 12/N to fit vessel frame E 12/B (only with PB-CSB 12/M)
• Sample vessels RG 2
• Set of 12 magnetic stirrer bars MRST 2
• Boiling chips SIST 100, 100 g
• COD air-cooled condenser LK 1
• Condenser stand LS for LK condensers
• Set of 12 PTFE std. taper joint sleeves PTFE 29
• Transport carrier TS CSB for vessel frame E/B
• Manual titration station HT 1

Precision heating blocks for 6, 12, or 24 samples. Surface heating for particularly even temperature distribution over all sample positions. Enclosure made of powder-coated steel and stainless steel. Non-hazardous temperatures of the enclosure surface thanks to the sophisticated insulation of the heating block.
Continuous grooves in the floors of the bores simplify sample handling and increase user safety:

• The grooves provide pressure compensation when the sample vessels are inserted. Thus, even precisely fitting vessels are easy to insert in the bores for user-friendly handling of the vessel frame.
• Traces of fluids on the outer walls of the sample vessels evaporate instantly when the samples are inserted into the heated block. The grooves discharge the steam and prevent glass breakage as a consequence of cracked vessels.
• In case of vessel overflow, the sample will flow off through the grooves, reducing the risk of acid damaging the heating block.

Programmable controller for behrotest® digestion blocks

behr single-button operation for particularly fast and easy programming. Menu in local language. 10 freely configurable programs for block temperature and digestion time. The TRS 300 has a special, factory preset CSB program (chemical oxygen demand of water/COD). In CSB/COD mode, it heats to a temperature 20°C above the specified setpoint temperature. After sample insertion, the setpoint temperate increased by 20°C is retained for another 6 minutes. This procedure ensures compliance with the ISO specification of heating to 148°C within 10 minutes, and simultaneously provides for an extremely constant temperature during the subsequent reaction process. With the Windows software comprised in the delivery, the user can transmit application-specific time/temperature profiles through the RS232 interface bi-directionally between one or several units (TRS 300) and one PC. Furthermore, the RS232 interface allows for transmission of temperature data from the unit to the PC while the unit is operating. If required, the data may be saved and printed out in form of a diagram.

In case of short-circuits or temperature sensor failure, the connected units will be switched off by means of the integrated safety functions.

The manual titration station HT1 consists of

• a burette with digital display, and
• a magnetic stirrer with accurately frame for COD sample vessels.

A screen is used as a neutral background, allowing the user an accurate identification of the color change at the end of titration. Thus, the user carries out all titrations under similar optical conditions, increasing the accuracy and reproducibility of the results. The exact positioning of the sample vessel in the rack on the top of the magnetic stirrer also contributes to this result. The inclined side panels of the screen provide an additional protection from lateral glare. COD pursuant to ISO, EN, and DEV.

behrotest® boiling stones are made from a ceramic material. Compared to conventional boiling stones made of glass, they provide optimum protection against defervescence due to their porosity and their shape, even with badly blended samples.

behrotest® boiling stones are chemically pure and guarantee unadulterated results when determining the COD.

Metering unit to automate and accelerate the metering of potassium chromate solution and sulphuric acid when preparing COD samples. Metering in a maximum of 12 samples simultaneously. Integrated series magnetic stirrer with 12 sample places.

• Metering in optimal time intervals: The metering of sulphuric acid is carried out in several processes, the samples are thus constantly cooled and stirred. This method accelerates the preparation of samples and at the same time prevents non-standard overheating of the samples during addition
• Safety for the user: Due to the automatic addition of reagent there is no risk at any time of coming into contact with chemicals
• Practice-oriented and user friendly software: The complete programming of the behr DS 20 is very easy to use and user-friendly with the Windows user interface

Dosing:
Time-optimized COD interval dosing. The metering of sulphuric acid is carried out in several processes, the samples are thus constantly cooled and stirred. This method provides for faster sample preparation while preventing a non-standard overheating of samples during addition.

Titration:
Freely programmable "methods", f.e. end point titrations, equivalence point titrations, linear, dynamic, and quasi-dynamic titrations. Different, password-protected user levels. Graphic printout with 1st and 2nd derivative. Freely selectable printout of sample data. Compliance with all national COD standards is possible with the "methods". Instead of the commonly known over-titration, the behr-specific dynamic titration guarantees the exact end-point recognition, even in the case of the typical COD edge steepness, and thus particularly accurate test results.

Safety for the user: Due to the automatic addition of reagent there is no risk at any time of coming into contact with chemicals.

• Practice-oriented and user friendly software: The complete programming of the behr DS 20 is very easy to use and user-friendly with the Windows user interface.

The cooling trough prevents the overheating of the COD samples during the critical addition of sulphuric acid. In addition, it is used to cool the samples after the heating phase. COD acc. to ISO, EN and DEV.

The continuously adjustable COD series magnetic stirrer with 12 stirring points is used to mix the samples during the metering process. Due to its watertight casing and also its external power supply and control, it is suitable for use under water.

The COD dosing funnel is placed on top of the COD reaction vessels. It simplifies the simultaneous addition of sulphuric acid to several samples. Combined with a cooling trough and a serial magnetic stirrer, it greatly improves safety and reliability and significantly eases the user's workload.

To expel chloride, e.g. when determining the COD of sea water.