YSI Instrument, Model 55 Discontinuation Notice

After decades of success, the YSI model 55 Dissolved Oxygen and Temperature Handheld  instrument will be discontinued February 2016.  This includes item numbers 055200, 055225 &  055250.  After February 29th, 2016, we will no longer accept orders for the model 55.  YSI will continue to support existing model 55’s for the next 5 years.  This is the last of the older-style YSI handhelds to be discontinued.

When looking for a replacement instrument, we suggest the Pro20 or ProODO handheld instrument as suitable replacements.  Both instruments are waterproof, rugged and designed for field use with metal, military spec connectors, IP-67 waterproof rating and 1 meter drop testing.

The Pro20 utilizes a membrane covered DO sensor, just like the 55, but uses cap membranes instead of stretch membranes,  making it much easier to replace the membrane.  Additionally, the Pro20 has a longer warranty, has an internal barometer that allows for a one-touch calibration and has user-replaceable cables and sensors.  In addition to connecting a field probe/cable assembly, the Pro20 can also be connected to a lab BOD-style probe.