Broadley James Dissolved Oxygen Probe 12 X 220 mm for 3-7L Bioreactors

The Broadley James (Model D540-B220) is a rugged polarographic (Clark-style) dissolved oxygen sensor designed specifically for controlling aerobic fermentation and cell culture processes. This sensor features a standard 12 mm diameter body manufactured from 316L stainless steel, with an insertion length of 220 mm. This specific length is most commonly used for top-entry installation in benchtop glass bioreactors (typically 3 to 7 Liters in size), where the probe must reach deep into the media to ensure accurate readings.

A defining characteristic of the "D540" series is its VarioPin (VP) connector. Unlike older standard 4-pin connectors (found on the D500 series), the VP connector is completely watertight (rated IP68) and robust. This allows the probe to be disconnected and reconnected safely even in wet environments, and it eliminates the contact corrosion issues often seen after repeated autoclaving. The sensor is engineered for durability, fully supporting both Steam-In-Place (SIP) cycles and autoclave sterilization up to 135°C. For maintenance, it utilizes a modular, replaceable membrane cartridge system (typically reinforced with a steel mesh), which allows users to rejuvenate the sensor in minutes rather than discarding the entire unit when the membrane fouls or degrades.