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Rugged and reliable, the YSI Pro20 provides everything you need in a handheld dissolved oxygen instrument. User-replaceable sensors and cables, 50 data set memory, and the convenient One Touch Cal feature makes it user friendly. Mil-spec (military spec) connectors, IP67 waterproof and rubber over molded case, and 1-meter drop test ensure the instrument remains in your hands to provide years of sampling even in the harshest field conditions. Fast response times allow you to complete your sampling routine quickly, saving time and money.

The Pro20 is an ideal meter for field work and lab BODs. Tough, smart and versatile.


Pro20 System Specifications (Instruments, Probe and Cable)
Temperature Range -5% to 55oC (0 to 45oC; DO compesation range for mg/L)
Resolution 0,1oC
Accuracy ± 0,3oC
Dissolved Oxygen % Saturation Range 0 to 500%
(galvanic or polarographic) Resolution 0.1% or 1% air saturation (user selectable)
Accuracy 0 to 200% air saturation, ± 2% of the reading or ± 2% air saturation, whicever is greater;
200 to 500% air saturation, ± 6% of the reading
Dissolved Oxygen mg/L Range 0 to 50 mg/L
(galvanic or polarographic) Resolution 0.01 or 0.1 mg/L (user selectable)
Accuracy 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
Barometer Range 400 to 999.9 mmHg
Resolution 0.1 mmHg
Accuracy ± 5 mmHg within ± 5oC termperature range from calibration point
Pro20 Additional Specifications
Size 8.3 cm width x 21.6 length x 2.3 cm depth (3.25 in. x 8.5 in. x 2.25 in)
Weight with Batteries 475 grams (1.05 lbs)
Power 2 alkaline C-cells providing 400 hours of battery life; low battery indicator on Pro20
Cables* 1- 4- 10- 20- 30- and 100-m lengths (special order up to 100-m)(3.28, 13.1, 32.8, 65.6, 98 ft) 
Salinity Input Range 0-70 ppt; manual (automatically compensates for manual input value)
Data Memory 50 data sets
Languages English, Spanish, German, French
Certifications RoHS, CE, WEEE, IP67 waterproof, 1-meter drop test

Product dimension

L X W X H = (21.6 X 8.3 X 2.3) cm


  • USer-replaceable cables and sensors. Choose polarographic or galvanic for the field or a self-stirring BOD probe for the lab.
  • One Touch Cal allows easy DO calibrations within 3 seconds with the press of a button. Automatic barometric pressure compensation.
  • Stores 50 data sets; no need to write down data.
  • Graphic, backlit display and glow in the dark keypad.
  • Available with 1- 4- 10- 20- 30- and 100-m cable lengths standard (special order up to 100-meter cables in 10-meter inrements).
  • Tough. IP67, impact-resistant, waterproof case even without the battery cover. Rubber over molded case provides extra durability. Military spec connectors.
  • A true field instrument - the display is visible with polarized sunglasses in.
  • Quick response times: 95% response time in approximately 8 seconds with standard membrane (fastest response time in the market).
  • Multiple languages include English, Spanish, French and German.


1 Unit

Product Application

To measure the dissolved oxygen in water

Expiration date

365 usage time

Technical Data Sheet