procurement of closed cod digester for laboratories under cwa ( w and s ) -i division , closed reflux cod ssytem scope of supply : cod photometer, cod digester with 24 samples digestion assembly at a time, test tube stand and vials ( 15-300 mg / ltr oxygen and 20-1500 mg / ltr. oxygen ) method : analogous to iso 15705:2002 measurement principle : photometry closed reflux system cod digester specification: construction materials : housing: abs , protection grid: pps , lid: pc , block insert: pbt , heating block: aluminium holes in the aluminum block : 24 holes, ø 16.2 mm ± 0.2 mm selectable temperatures : 100 / 120 / 150 °c probe type : pt 100 a class temperature stability at pt 100 : ± 1 °c selected time : 30 / 60 / 120 / continuous ( 8 ) min heating up from : ( 20 °c --> 150 °c ) 12 min thermoregulation : microprocessor protection against overheating : at the auto block for 190 °c photometerspecification: instrument : double wavelength, automatic wavelength selection, direct reading colorimeter light source: : leds, interference filters ( if ) and photo sensor in transparent cell chamber. wavelength specifications of the if: 430 nm ?? = 5 nm, 610 nm ?? = 6 nm wavelength accuracy : ± 1 nm photometric accuracy : 3% fs ( t = 20° c – 25° c ) photometric resolution : 0.01 a power supply : 4 batteries ( aa / lr6 ) operating time : 17hr operating time or 5000 measurements in constant use when display backlight and bluetooth® data transfer are off auto-off : automatic switch off 10 minutes after last key press interface : bluetooth® 4.0 for the transfer of stored measurement data time : real time clock und date calibration : user and factory calibration , resetting to factory calibration possible ambient conditions : temperature: 5 – 40 °c , rel. humidity: 30– 90 % ( non-condensing ) portability : bench top. certification : the manufacturer should have iso certification for manufacturing water testing instruments and reagents , vials ranges and methods : low range: 3 - 150 mg / l, meets iso 15705:2002 ( 500 vials ) middle range: 20 - 1500 mg / l, meets iso 15705:2002 ( 3200 vials )