Gallium Cell and Maintenance System

Features Summary

• Maintains gallium melting plateaus for five days or longer
  System uncertainty of 0.08 mK
  Firmware automates melting and refreezing processes
  "Smart" gradient freezes cells from bottom up
  Automated 8-watt heater provides inner melt
  Model 5943 Stainless Steel Gallium Cells are sealed for longer life and easier shipping
  Two pre-heat wells for maximum productivity

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The gallium melting point (29.7646°C) is a critical temperature. Thermometers used in life science, environmental monitoring, and many other applications depend on it for accurate calibrations. Lab standards rely on it as an ITS-90 check standard and as a means of measuring drift between calibrations. Hart Scientific now makes it easy to use.

The new Model 9230 Gallium Maintenance System works with Hart’s Model 5943 Stainless Steel Gallium Cell to provide melting plateaus that last a week . Not a day. Not a day-and-a-half. One week.

The Model 5943 Stainless Steel Gallium Cell holds a gallium sample that is 99.99999+% pure. The gallium is sealed in a Teflon envelope in a high purity argon atmosphere, which is itself sealed inside a stainless steel housing. This double-sealing method reduces leaching of the gallium sample and ensures a life of ten years or longer for the cell.

The 5943 achieves 29.7646°C with uncertainty of just 0.08 mK and reproducibility of 25 mK. With the 9230, realizing and maintaining the gallium melting point is fast and easy. Years of training are not required.

When not actively melting or refreezing a gallium cell, the 9230 automatically “rests” at 29.27°C, just below the gallium melting point. To initiate a melt, just insert the attached melt heater into the gallium cell and start the “melt” routine through the 9230’s front-panel buttons. The 9230 increases its temperature to just above the gallium point and powers the 8-watt melt heater. Less than 30 minutes later, the gallium cell is ready to be used. Realizing the gallium point requires only a few seconds from the user.

Because the high quality of the 5943 Gallium Cell is combined with the ultrastable performance of the 9230 Maintenance System, melt plateaus last 5–7 days or longer.

Two preheat wells ensure that thermometers are properly warmed when inserted into the gallium cell. The preheat wells are even oversized so thermometers fit loosely and heat loss from the gallium cell is neither too sudden nor too severe when cold thermometers are initially placed in the wells.

When the melt plateau is exhausted, the 9230 automates the preparation of the gallium cell for its next melt. After the user initiates the “freeze” routine through the front panel, the 9230 heats to well above the melting point to ensure a complete melt of the entire gallium sample. Then the 9230 automatically cools to refreeze the gallium. Since gallium cells must be frozen from the bottom up (like water, gallium expands when it freezes), the 9230 induces a 10°C differential during the freezing process to safeguard the cell from damage.

Using a 5943 Gallium Cell, the 9230 delivers uncertainty of ±0.00008°C with virtually no effort from the user. It uses a long-life sealed cell.