Accurity™
Hydrogen Measurement in Liquid Aluminium
Accurity™
Hydrogen Measurement in Liquid Aluminium
Hydrogen Measurement in Liquid Aluminium
Hydrogen Measurement in Liquid Aluminium
The Accurity™ unit gives immediate measurements of the hydrogen content in liquid aluminium from an immersed probe. It works based on a gas circulation principle that has been used in the industry for hydrogen measurement for more than 30 years.
Plants handling liquid aluminium need to make sure the dissolved hydrogen is kept at the right level. The global market demands good quality aluminium with hydrogen specifications.
Cast at the right hydrogen level
Aluminium plants often use degassers and fluxes to remove hydrogen from the melt. When the hydrogen is too high, the casting may suffer poor quality due to high porosities. Measuring with Accurity™ will tell you if your liquid aluminium is at the right level before casting.
Control your process
If the degasser is not performing as usual, the hydrogen level will be affected. Measure with Accurity™ to verify the hydrogen level.
The use of an iPad tablet makes it easy for the user to set the measurement parameters and start a measurement. The tablet is connected to the unit. The software application (iOS app) made by Alsobia operates the unit and manages all sensor data. It also displays instructions to the users when relevant.
Users can enjoy the bright display showing the hydrogen measurement results in real time at the measurement location.
The tablet is well protected inside a locked metallic case and covered by an acrylic glass panel. When required, the user can lift up the panel to use the touch screen.
Note that the touch screen is not required for basic operations like starting a measurement. The side button can also be used.
No need to take off your gloves, you can easily start or stop a measurement by pressing the big button on the side of the unit.
The hydrogen measurement is made possible by immersing a probe in liquid aluminium. This probe will catch the hydrogen from the melt and bring it to the unit. The Accurity™ can then make a measurement of the hydrogen.
This probe design has been used in the aluminium industry for more than 30 years and is proven to be efficient and accurate for hydrogen measurement.
The same probe can be used in all aluminium alloys including wrought and foundry alloys containing silicon.
The same probe can be reused for 10 immersions or 3 cumulative hours in the melt.
The cumulative immersion time (probe age) is indicated on the Accurity™ display. This helps the users to know when the probe should be replaced. When the probe does not provide a good hydrogen reading, the app will suggest it replacement.
The aluminium temperature is required for calculation of the hydrogen concentration in liquid aluminium. This is provided by a thermocouple installed on the Accurity™ and immersed with the hydrogen probe.
The hydrogen level in the melt is influenced by humidity in the air. The Accurity™ has a humidity and temperature sensor on the unit. For each hydrogen measurements, the ambient conditions are recorded for reference.
Easy to carry by one person. The user can bring the Accurity™ unit at the measurement location, beside the liquid metal. Then, the hydrogen probe and thermocouple are immersed in liquid aluminium.
If space is available, it can just be put on a flat surface by the launder or furnace. Or it can hang on the side by its hooks.
The Accurity™ electronics inside the enclosure are protected from the liquid metal heat radiation by a heat shield facing the metal. If the unit sits on a hot surface, the base shield will prevent the Accurity™ enclosure from getting too much heat.
The Accurity™ unit needs pure nitrogen as carrier gas for the hydrogen measurement. The unit has a built-in gas bottle filled with pure nitrogen. So there is no need to have any gas supply at the measurement location.
When the bottle is empty, it can be refilled from a nitrogen source using the provided pressure regulator.
Accurity™ works using a well-known principle that has been used for many years as the reference method for hydrogen measurement. It is the recirculation loop principle.
A fixed quantity of pure nitrogen gas repeatedly circulates in a probe immersed in liquid aluminium. At the probe tip, the nitrogen is brought in contact with the aluminium. Dissolved hydrogen in the aluminium will then mix with the nitrogen up to a certain quantity. This quantity is reached when the hydrogen partial pressure in the nitrogen is the same as the hydrogen vapour pressure in the melt. The Accurity™ performs an exact measurement of hydrogen in the nitrogen by thermal conductivity. This measurement is converted into a hydrogen concentration in liquid aluminium in mL/100g (milliliters of hydrogen gas per one hundred grams of aluminium).
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