Specification :

The rugged, waterproof YSI 550A measures dissolved oxygen and temperature simultaneously using polarographic technology and YSI Temperature Precisionâ„¢ thermistors. The new PE membranes allow for faster response times with less stirring dependence. Measurements are fast and easy with one-handed operation, easy-to-use backlit display, automatic push-button calibration, and a weighted, quick-sinking probe.

Other features include field-replaceable DO electrode modules, waterproof housing ( meets IP-67 specifications) , impact-resistant case, 2, 000+ hours battery life, screw-on cap membranes, calibration in either mg/ L or % saturation, user-selectable temperature units ( ° C or ° F) , a built-in calibration chamber, low-battery indicator, and direct compensation for salinity, temperature, and altitude. CE compliant. Available with 12-, 25-, or 50-foot cable lengths. Three-year warranty on the instrument. One-year warranty on the DO module. Powered by 4 C cell Batteries.

Specifications:
Range: Dissolved Oxygen: 0% to 500% air saturation; 0 to 50 mg/ L; -5º C to 45º C; Temperature: -5º C to 45º C.
Resolution: Dissolved Oxygen: 0.1% air saturation or 1% selectable; 0.01 mg/ L or 0.1 mg/ L selectable; 0.1º C; Temperature: 0.1º C.
Accuracy: Dissolved Oxygen: 0% to 200% : ± 2% air sat. or ± 2% of reading, whichever is greater; 200% to 500% : ± 6% of reading; 0 to 20 mg/ L; ± 0.3 mg/ L or ± 2% of reading, whichever is greater; 20 to 50 mg/ L: ± 6% of reading; ± 0.3º C; Temperature: ± 0.3º C.
Salinity Compensation: Yes.
Altitude Compensation: Yes.
Temperature Compensation: Automatic.
Battery Life: Over 2, 000 hours.