As microbes subdivide every twenty minutes, they become increasingly oxygen-starved. The supply of sufficient oxygen during brewing is critical.

The Dissolved Oxygen Meter is an essential instrument for the serious microbe brewer. The level of dissolved oxygen in the solution seriously affects the quality and diversity of any brew. The vast majority of beneficial fungi and bacteria are obligate aerobes (they need oxygen to live) and a level of 5 ppm has been outlined by the Soil Foodweb Institute as the minimum threshold level of dissolved oxygen necessary for an aerobic brew. Food, temperature, altitude and population all impact on the level of dissolved oxygen in the solution. This tool provides a fast, easy and accurate way to measure the dissolved oxygen level of the brew.

Features:

• The unit can be used to assess dissolved oxygen in a wide range of solutions.
• It can also be used to assess oxygen levels in CA (controlled atmosphere) storage facilities

Packaging:

• The unit is supplied in a high-density plastic carry case that is lined with shock absorbent foam. The kit includes a 3 metre cable, spare sample tip and o-ring, cover cap, 9 volt battery, 30ml refill solution for the electrode and 50ml dissolved oxygen solution. The unit comes wet-tested with the probe pre-calibrated.
• Note: Due to the value of this tool, it will be sent via registered post (normal postage + $2.00 for the first $100 in value + $1 for every $100 in value thereafter). Weight: 1400grs.

Mode of Action:

The meter relies on changes in electrical potential (voltage) - measured in the sensor head - to indicate the level of dissolved oxygen wherever the sensor head is positioned. It uses a platinum cathode (situated in the sensor tip) and a silver chloride anode (windings surrounding the neck of the sensor head). Current is passed between the two at a fixed voltage of approx 800mV. The passage of this current consumes dissolved oxygen in the sensor chamber. The sensor is filled with electrolyte solution and is separated from the atmosphere by a semi-permeable membrane. This membrane allows only dissolved oxygen to enter the sensor chamber, a change in the oxygen level causes a change in the electrical potential which is converted by the unit and displayed on the LCD in ppm DO (parts per million Dissolved Oxygen). For efficient microbial multiplication the DO level should be maintained above 5ppm.

Information:

• The unit is a sensitive tool and should be treated accordingly. The membrane can be easily torn if dropped onto the bottom of a brewing tank - avoid impacts.
• For readings to be accurate and repeatable, it is essential that the membrane is not damaged and the sensor chamber is filled with sufficient electrolyte solution.
• When not in use, ensure the probe cover is on the sensor to prevent damage to the membrane.
• The display unit is not waterproof and has access points on the front and back for calibration -for this reason it should not be splashed or placed in positions where it can get wet.
• When measuring the dissolved oxygen concentration the unit uses up the oxygen - for this reason it is necessary to keep the sensor head moving when a reading is being taken.
• If the display unit becomes dirty, wipe over with a clean rag moistened with water only. The sensor head and cable should be rinsed clean after each use to avoid contamination. The membranes porosity becomes limited if it is left soiled with brew water.
• Store the unit in the case provided.
• The unit should never be dropped.
• Check the calibration of the unit before taking a reading by measuring the atmospheric level and comparing it to the chart on page 5 of the user manual.

© Steve Cselka 2002 - 2011