Water Quality System (WQS)
Field & Laboratory Meters
  • pH, SCT, DO & BOD, Multi-parameter Testing
Environmental Monitoring Systems (EMS)
Multi-parameter Water Quality Sondes
  • Sampling, Logging& Profiling

Integrated Systems & Services (ISS)
Environmental Monitoring Modules
  • Buoy& Floating Platforms, Profiling Systems, EcoMapper AUV

WQS_Handheld Field Instrument

Pro20/Pro20i Dissolved Oxygen Instrument


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:

  • Internal barometer for highest accuracy
  • Choose field DO sensors (Polarographic or Galvanic) or lab BOD probe for BOD in wastewater
  • One Touch Cal calibrates within 3 seconds with the push of a button
  • Stores 50 data sets
  • Graphic, backlit display and glow in the dark keypad
  • Available with 1, 4, 10, 20, 30 or 100-meter cables
  • View display with polarized sunglasses on
  • Fastest response time on the market with 95% response in 8 seconds with standard membrane
  • Multiple languages include English, Spanish, French and German
  • User replaceable sensors and cables 
  • 3-year instrument; 2-year cable warranty

Lab or field - the Pro20 is ready for whatever you need when it comes to oxygen meters.


Easy to use, rugged and reliable, the YSI Pro20i provides everything you need in a handheld instrument for the measurement of dissolved oxygen. User-friendly and convenient calibration routine and 50 data set memory. A true field instrument with IP67 waterproof, rubber over molded case, and 1-meter drop tests ensure durability to provide years of sampling even in the harshest field conditions.

Features Include:

  • Integral (i.e. built-in) cable with 1- 4- 10-m field cable; user-replaceable DO sensors
  • One Touch Cal allows for easy DO calibrations within 3 seconds with the press of a button. Automatic barometric pressure compensation.
  • Quick response times; 95% response time in approximately 8 seconds with standard membrane (fastest response time on the market)
  • Stores 50 data sets; no need to write down data
  • Large graphic, backlit display and glow in the dark keypad
  • A true field instrument - the display is visible when wearing polarized sunglasses
  • Tough. IP-67, impact-resistant, waterproof case. Waterproof with and without the battery cover
  • Rubber over molded case provides extra durability
  • Multiple languages: English, Spanish, French, and German
  • 3-year instrument; 2-year integral cable; 1-year polarographic sensors; 6-month galvanic sensor warranty

The Pro20i features an integral cable, but the Pro20 features a user-replaceable (i.e. detachable) cable. Longer cables are also available for the Pro20, as is a BOD probe/cable assembly.

YSI Pro20 Dissolved Oxygen Instrument


1-meter drop test, WEEE, RoHS, IP-67, CE, Assembled in USA 


MS (military spec) waterproof with bayonet lock

Digital / Digital Sensors: 


Equipment used with:

ProBOD, ProSeries 20-x cables


German, French, Spanish, English

Logging Capabilities:


Measurement Range:

0 to 500%; 0 to 50 mg/L


50 data sets



Parameters Measured:

Temperature, Dissolved Oxygen, Built-in barameter



Unit of Measure:

Dissolved Oxygen-%, air saturation, °F, Temperature- °C, mg/L, Barameter-mmHg

User Replaceable:



3-year instrument; 2-year field cables


YSI Pro20i Dissolved Oxygen Instrument

Cable Options:               1- 4- 10-m lengths (3.28, 13.1, 32.8 ft.)
Certifications: RoHS, CE, WEEE, IP-67 waterproof, 1-meter drop test
Languages: English, Spanish, German, French
Memory: 50 data sets
Size: 8.3 cm width x 21.6 cm length x 5.6 cm depth (3.25 in. x 8.5 in. x 2.2 in.)

3-year instrument; 2-year cable; 1-year polarographic sensors; 6-month galvanic sensors


475 grams (1.05 lbs.) (with batteries)


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