Field Dissolved Oxygen & Temperature Meter
The Pro20 provides everything you need in a handheld dissolved oxygen meter. Ruggedness, simplicity and reliability are the cornerstones of the instrument's design.

Have a question about your Pro 20 Dissolved Oxygen (DO)? Check out the support page with resources compiled just for you.
Need service for your system? Here you’ll find authorized service centers and instructions on how to get the service you need.
We have a large pool of water quality and hydrology instruments available to you for rental.
The YSI Pro20 dissolved oxygen meter is a rugged, user-friendly instrument for dissolved oxygen measurement. The Pro20 can be used in the lab or the field and can go from one to the other in seconds.
User-replaceable sensors and cables and convenient One Touch Cal feature makes it extremely user friendly. Mil-spec (military spec) connectors, IP-67 waterproof and rubber over molded case, and 1-meter drop tests ensure the instrument remains in your hands to provide years of sampling even in the harshest field conditions. The feature set of the Pro20 results in a low total cost of ownership over the life of the product.
Fast response times with the Polarographic or Galvanic dissolved oxygen sensors allow you to complete your sampling routine quickly. The long life of the Polarographic sensor saves time and money and reduces your overall cost. The Galvanic sensor enables you to start sampling immediately without a warm-up period. Either sensor you choose for the field will give you accurate, quality data.
Additional features include:
Lab or field - the Pro20 is ready for whatever you need when it comes to oxygen meters.
When ordering the YSI Pro20 you must order the instrument, cable, and dissolved oxygen probe separately, allowing you to choose the system that best fits your application.
If you're interested in learning more about optical dissolved oxygen technology and the YSI ProODO optical DO instrument please visit the ProODO page.
Please visit our extensive dissolved oxygen resource page to learn about all things DO and BOD related; www.YSI.com/weknowDO
Pro20 Instrument General Specifications
Pro20 System Specifications (Instrument with Cable & Probe)
| Sensor Type | Range | Accuracy | Resolution | |
| Dissolved Oxygen (%) | Polarographic or Galvanic | 0 to 500% air saturation | 0 to 200% air saturation, ± 2% of the reading or ±2% air saturation, whichever is greater; 200 to 500% air saturation, ± 6% of the reading | 0.1% or 1% air saturation (user selectable) |
| Dissolved Oxygen (mg/L) | Polarographic or Galvanic | 0 to 50 mg/L | 0 to 20 mg/L, ± 2% of the reading or ±0.2 mg/L, whichever is greater; 20 to 50 mg/L, ± 6% of the reading | 0.01 or 0.1 mg/L (user selectable) |
| Temperature | -5 to 55°C (0 to 45°C; DO compensation range for mg/L ) |
±0.3°C | 0.1°C | |
| Barometer | 400 to 999.9 mmHg | ± 5 mm Hg within ± 5°C temperature range from calibration point | 0.1 mm Hg |
Ordering Guide
Ordering Guide for Pro20 Kits
| Item # | Description | Included in Kit |
| 603168 | BOD Kit, US | Pro20 meter, ProBOD self-stirring BOD probe, Lab Dock , US power supply (073035) |
| 603222 | BOD Kit, INT | Pro20 meter, ProBOD self-stirring BOD probe, Lab Dock, International power supply (073047) |
| 603169 | Pol DO Lab/Field, 4-m | Pro20 meter, ProBOD self-stirring BOD probe, 4-meter field cable with polarographic DO probe, Lab Dock, US power supply (073035), soft-sided carrying case (603162) |
| 603170 | Gal DO, 4-m | Pro20 meter, 4-meter field cable with galvanic DO probe, soft-sided carrying case (603162) |
| 603171 | Pol DO, 4-m | Pro20 meter, 4-meter field cable with polarographic DO probe, soft-sided carrying case (603162) |
| 603172 | Gal DO, 10-m | Pro20 meter, 10-meter field cable with galvanic DO probe, soft-sided carrying case (603162) |
| 603173 | Pol DO, 10-m | Pro20 meter, 10-meter field cable with polarographic DO probe, soft-sided carrying case (603162) |