Several companies manufacture freeze-point furnaces. Most of these furnaces are of adequate theoretical design and of reasonable quality. Most are priced similarly. However, there is a difference that can’t be seen from specifications or price, and that’s how well the furnace performs with the freeze-point cells they’re designed to maintain.

Establishing and maintaining a freeze-point plateau is what these furnaces are supposed to be about. Nothing they do is more important than this performance issue.

Hart Scientific makes three freeze-point furnaces that, when combined with Hart freeze-point cells, produce the longest plateaus in the industry. Generally, a Hart furnace and cell establish plateaus that range from 24 to 40 hours or more.

Fixed-point furnaces can also be used for comparison calibrations and for annealing. In these processes, stability and uniformity are very important, and nothing speaks more about stability and uniformity than the length of the plateaus produced by the furnace. No other furnace beats a Hart furnace where it counts.

All three of these furnaces have external cooling coils for circulation of tap water at less than 60 PSIG and approximately 0.4 GPM to reduce heat load to the lab. They also come with RS-232 ports and have equilibration blocks available for comparison calibrations. IEEE-488 interface packages are also available if that’s your preference.

One of Hart’s three fixed-point furnace models will meet your needs. Remember, the length of the plateau is the best measure of a furnace’s performance. Call us for performance data on actual cell freezes and test data on furnace gradients.


9114 
This furnace has a range of 100°C to 680°C, which includes the indium, tin, zinc, and aluminum fixed points all in one furnace.

The Model 9114 furnace has an inlet for use of clean dry or inert gas to initiate the super-cool of a tin cell. Other furnaces require the user to remove the hot and fragile tin cell from the furnace by hand before cooling. In a Hart furnace, you simply turn on your gas, monitor your cell during its supercool, and turn the gas off when the freeze begins.

The Model 9114 is a three-zone furnace with the best in Hart digital controller technology. Hart designs and builds proprietary controllers that have a reputation of being the best in the business. All of our fixed-point furnaces use them to achieve excellent stability and uniformity.

For easy access and visibility, all three zones are controlled from the top of the unit. The primary controller can be set in 0.01°C increments, and actual temperature is readable to two decimal places.

The freezing and melting process can be automated using eight preset, user-programmable temperature settings. The top and bottom zones are slaved to the primary zone using differential thermocouples. A high-temperature PRT acts as the main control sensor for the best accuracy, sensitivity, and repeatability.