Suggestions and recommendations The heating system is not included with the ProboStat cell system. Furnace, power supply and controller must thus be obtained separately. The furnace should be a tubular type of >40 mm inner diameter. It should preferentially be vertically mounted, but horizontal operation is possible. A total furnace length of up to 80 cm is possible, a typical length may be around 50 cm, but many applications and types of uses may actually benefit from even shorter furnaces, down to, say, 35 cm total length, or 25-30 cm heated length. An ordinary tubular furnace should have up to 100 cm of space underneath to enable the cell to be inserted into the furnace from below. Typically, the furnace is mounted on a wall or put on a shelf or long-legged table with a hole in the table-top. As an alternative, a hinged (split) furnace, or a furnace mounted on a lift has the advantage that the cell may remain still during sample remounting etc. For the ProboStat, choose vertical tube furnace models, e.g. with 50 mm diameter opening and 300 (or 450) mm heated length. Examples: TSV12/50/300 for <1200°C operation or TSV16/50/450 for <1600°C operation. Elite may deliver a stand that raises the furnace above your ProboStat and lets you lower it over the ProboStat. Order codes indicate: Max temperature ##00°C/work tube diameter mm/heated length mm. For the ProboStat choose vertical ##/50/300 or ##/50/300 models. We suggest one of: LTF 12/50/300, LTF 14/50/450, LTF 15/50/450 or LTF 16/50/450 depending on temperature. Entech produces furnaces to order, and has for instance provided custom furnaces to 1400°C for ProboStat customers. NorECs delivers custom-made mantles from Glas-col, for using ProboStat at moderately high and near-ambient temperatures. Commercial, standard furnaces usually come with a simple PID controller connected to the furnace's own internal thermocouple. You can use this to control the temperature, while monitoring the cell temperature through one of its own thermocouples. However, it is usually better and more convenient to control the temperature directly from the cells thermocouple, since you then get exactly the temperature you want, and you keep it very constant. The extra thermal length and slower response is usually no problem for modern PID controllers, especially at high temperatures. If you want to use the cell's thermocouple on a furnace with built-in thermocouple you may want to do one of the following: Get a cascaded controller (e.g. Eurotherm 2704) which takes input from both the furnace's and cell's thermocouples and makes the best and safest control out of the two. or Install an extra thermocouple contact and a manual switch to select one or the other thermocouple to be used for control. This requires precaution and/or overheating protection in the case you withdraw the cell from the furnace while the cell's thermocouple is still connected and used for control. Also remember to have the ProboStat and the furnace with the same type of thermocouple. NorECs manufactures a power supply with controller that is functional for such cases (provided the heater runs on 220-240 V AC mains power). At low temperatures it may become difficult to achieve control with the cell's internal thermocouple if you have a powerful furnace designed for higher temperatures. Nevertheless, in our opinion, a normal PID controller connected to the cell's internal thermocouple, and a powerful high temperature furnace, can well control the ProboStat from the top temperature and down to, say, 3-400°C with suitable setting of the PID parameters and reduced maximum power limit. Even lower temperatures can be reached by tuning these parameters specially. We have experience in Oslo that a Eurotherm 2216 controller can control a 1500 W 1300°C furnace from the thermocouple inside the ProboStat even at 50°C! Here is a collection of suggestions to further control "low temperatures":Auxiliary equipment for the ProboStatTM
Temperature control
Furnaces
Requirements
Some furnace suggestions
furnaces. Website: http://www.elitefurnaces.com 
furnaces. Website: http://www.lentonfurnaces.com/products_furnaces_ltf.htm 
furnaces. Website: http://www.entech.se 
Glas-col. Website: http://www.glascol.com Temperature controllers
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consider use the furnace's own thermocouple for control, if there is one |
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consider using a cascaded controller, |
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decrease the size and power of the furnace, or use a heating mantle instead, |
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apply water or air cooling of the furnace, |
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decrease the heater's input voltage if possible, |
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decrease the maximum power limit of the controller, |
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adjust the PID settings to prevent oscillations. |
NorECs manufactures a custom power-supply and temperature controller intended for furnaces without own supplies/controls, and for furnaces with their own thermocouples, but where the ProboStat internal thermocouple is used for control and the furnace thermocouple is used for security, or where one wants to switch between the two in order to achieve low temperature control.
