What is the Accuracy of pH electrodes?

The McGraw-Hill Dictionary of Scientific and Technical Terms defines “accuracy” as: “The extent to which the results of the readings of an instrument approach the true values for the measured quantities, and are free from error.” This is not possible to do with pH or ORP (Redox) electrodes, because they…

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What is a pH Electrode Life Expectancy?

How long should an electrode last in storage? Fermprobes can be stored for up to one year from date of shipment with no appreciable change in their performance or expected service life. After a year, the electrodes are still good but their potential for optimum performance slowly erodes until they…

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What are the white crystals on my FermProbe?

The white crystals you may find on your electrode are formed by the potassium chloride (KCI) in the electrode storage solution. The crystals will not affect the electrode’s performance. Rinse the electrode with DI water and proceed as usual.

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How do I select a sensor for benchtop vessels?

Typically a benchtop application is less than 5L, and uses a glass vessel or flask. Usually the entire vessel can be placed or wheeled into an autoclave for sterilization prior to a run. Not only is there a range of different vessel sizes used in benchtop bioprocess applications, but also…

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How Do I test My OxyProbes?

Purpose for test: Dissolved oxygen membrane cartridges contain an oxygen-permeable, polymer membrane, which is impermeable to liquid. Improper storage or accidental handling of the DO sensor or membrane cartridge can damage the polymer membrane. A hairline scratch, slight abrasion or any tear of the polymer membrane may render the cartridge…

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What is the difference between a 2-wire and a 4-wire transmitter?

2-Wire vs. 4-Wire: A 4-wire transmitter is either powered by a 110V or 220V power supply. This allows direct activation of relays, pumps, solenoids, etc. However, in a hazardous environment, flammable or combustible vapors, gases or dust are present which could possibly ignite under certain circumstances. A 2-wire transmitter is…

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What is sensor interrogation?

Sensor interrogation is a feature of many transmitters today. It can be used to determine whether or not the sensor is working properly by sending a signal through the sensor and monitoring the response. The response will indicate whether the sensor is cracked, broken, clogged or otherwise not operating properly.…

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How should I install a pH Sensor?

A pH sensor must be at least 15° above horizontal to consistently function properly. DO NOT install sensors in a port perpendicular to the vessel wall. The liquid in the sensor contains small air bubbles. If not inclined slightly above horizontal, a bubble can adhere to the pH bulb where…

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