YSI 550A Dissolved Oxygen Instrument

True Field Performance
Looking for a rugged, field-worthy instrument for measuring dissolved oxygen? The new YSI 550A DO features a waterproof IP-67, impact-resistant case and innovative field-replaceable DO electrode modules. Measure dissolved oxygen and temperature simultaneously using YSI's proven polarographic technology for oxygen and YSI Temperature Precision TM thermistors, the worldwide standard for accuracy.
  • Waterproof! Meets IP-67 specifications Field-replaceable DO electrode modules
  • Screw-on cap membranes
  • Over 2000 hours battery life
  • Calibrate in either mg/L or % saturation
  • User-selectable temperature units (°C or °F)
  • 12, 25, 50, and 100-foot cable lengths
  • Expanded DO and salinity ranges for a wider application range

Three-year warranty on the instrument and one-year on the DO module and cable!

Packed With Features
Measurements are fast and easy with one-hand operation, an easy-to-use backlit display, automatic push-button calibration, and a weighted, quick-sinking probe. The YSI 550A DO has a built-in calibration chamber, low-battery indicator, direct salinity, and altitude compensation. The instrument provides simultaneous readings of oxygen and temperature. Dissolved oxygen readings are automatically compensated for temperature.
550A-12 YSI 550-A 12' cable $755.00
550A-25 YSI 550-A 25' cable $795.00
559 DO Module $151.50
5908 Membrane Kit $45.00
  • Call Toll Free 800-850-7274 to order today!
YSI 550A Dissolved Oxygen Specifications
Fresh, sea or polluted water
Dissolved Oxygen Sensor:
Steady-State Polarographic
Dissolved Oxygen Probe:
Field-replaceable module
0-20 mg/L; +0.3 mg/L or +2% of reading, whichever is greater
20-50 mg/L; +6% of reading
0-200 %; +2% air saturation or +2% of reading, whichever is greater
200-500%; +6% of reading
0-50 mg/L
0-500 % air saturation
-5°to +45° C temperature
0.01mg/L or 0.1 mg/L, user selectable
0.1% air saturation or 1%, user selectable
0.1°C temperature
Temperature Units:
Celsius or Fahrenheit, user selectable
Temperature Specifications:
Accuracy: +0.3°C
Range:-5°to +45° C
Resolution: 0.1°C 
Altitude Compensation:
Salinity Compensation:
Automatic (0-70 ppt)
Temperature Compensation:
4 alkaline C-cells
4.7 in. width; 9 in. length (11.9 cm x 22.9 cm)
Weight with Batteries:
2 lb. (0.91 kg)
Battery life:
Over 2000 hours at 25°C
12, 25, 50, or 100-foot lengths
Other Features:
Waterproof to IP-67
High impact resistance
Push-button calibration
Built-in calibration chamber
Large, backlit display
Low battery indicator on display
CE compliance
3-year for the instrument
1-year for the DO module


Let us repair and service your YSI meters!
We have a factory trained technician on duty 24/7.

48 hour turn a round time on most repair work!

Southern Aquaculture Supply, Inc. (MainOffice)
PO box 326
931 Saint Mary's Street
Lake Village, Arkansas  71653

We accept Visa, Master Card & American Express

For Pond and Lake Management Consultants visit :