These gas-tight retort furnaces with indirect heating outside the retort are particularly suitable for heat treatment requiring a constant defined protective gas or even reactive gas atmosphere in the furnace chamber. The working chamber consists of a gas-tight retort with water cooling in the door area to protect the special seal. Depending on the temperature range to be applied in the furnace, we recommend different versions for optimizing the temperature distribution. The basic furnace alone attains a temperature uniformity of ΔT 30K at temperatures above 800°C according to DIN 17052. Additional equipment can further optimize these furnaces for reaching a temperature uniformity of up to ΔT 10K in other temperature ranges as well:

• For a working range up to approx. 500 °C the furnace is equipped with gas circulation with a fast running fan in the door.
• Between 500 °C and 800 °C the heating should also be divided into three zones and controlled.
• Above 800 °C, three-zone control without gas circulation is the proper version.

The basic furnace is prepared for operation with a nonflammable protective gas. Equipment is also available for operation with other gases up to safe operation under hydrogen. By optimizing with various additional equipment, i.e. with cascade control, you can customize the furnace for the particular process. A vacuum pump can be employed to cold-evacuate the furnace, among other purposes, for reducing the gas consumption during pre-purging.

• Tmax 1100 °C
• Gas-tight retort for heat treatment in a constant defined atmosphere
• Operation with nonflammable protective gases including nitrogen, argon, forming gas (95/5)
• Open coolant system for the door seal
• Radiation protection plates for reducing the temperature drop at the door
• All-round heating of the retort for good temperature uniformity
• Manual gas injection with stopcock, flow meter and control valve, with complete tubing

• Retort with optional connection for vacuum pump for cold-evacuation
• Base frame included

Additional equipment

• Upgrade for other nonflammable gases
• Automatic gas injection, including MFC flow controller for alternating volume flows, PLC-controlled
• Gas injection package for operation under hydrogen, including comprehensive safety package and PLC control for monitoring the safety functions
• Vacuum pump for cold-evacuating the retort
• Gas circulation with fast running fan for working temperatures up to 500 °C
• Multi-zone control and gas circulation for working temperatures between 500 °C and 800 °C
• Multi-zone control for working temperatures above 800 °C
• Cooling system for shortening process times
• Package for debindering or for pyrolysis under protective gas with defined discharge and the corresponding safety technology
• Temperature control via the retort inside chamber with temperature measurement inside and outside the retort as cascade control

These pit-type retort furnaces are particularly suitable for annealing of heavy charges or charge baskets handled by crane which require heat treatment under protective gas in a defined atmosphere. Just like the models N 21/M etc., these furnaces can be evacuated at ambient temperatures to reduce gas consumption during pre-purging. Alternatively, furnaces S 500/RA and larger are available with interior retort gas circulation to further improve temperature uniformity.

S 100/R - S 1000/R

• Pit-type retort furnaces for heat treatment in a defined protective gas atmosphere
• Maximum temperatures of 1100 °C
• Gas tight alloy retort with protective gas inlet and outlet
• Port for temperature measurements in the chamber
• For all non-flammable protective gases including nitrogen, argon, or forming gas 95/5
• Water-cooled lid with ‚O‘ ring sealing
• Heating from four sides
• Optimum temperature uniformity (according to DIN 17052-1) up to ΔT 14 K
• Pneumatic or hydraulic lid lifting

Additional Equipment for Standard Models S 500/RA - R 1000/RA

• Gas circulation with fan in the lid for optimum temperature uniformity according to DIN 17052-1 up to ΔT 6 K
• Water-cooled motor flange

Additional Equipment

• Manual or automatic gas supply panel
• Automatic exhaust damper and cooling fan for rapid cooling
• Control of retort temperature inside
• Vacuum pump for evacuating the retort at ambient temperature prior to heat treatment for reduced pre-purge times and gas consumption
• Cooling station, additional retort for increased productivity
• Custom sizes up to 3,000 liters and charge weights up to 5,000 kg
• Charging baskets and devices