Our Hydrogen Bell Jar Furnace features a space-saving design and includes an electric actuator raising the chamber for easy and complete access to the loading area. Pneumatic  locking clamps ensure a vacuum-tight seal isolating the chamber environment.

A retort with an independent gas line keeps binders and volatile products from entering the hot zone, while at the same time improving temperature uniformity. The gas exit has a burn-off assembly for removal of hydrogen or other flammable gases.

Hydrogen Bell Jar Furnace


General Specifications

  • 2000°C Maximum (3632 F) without molybdenum retort
  • 1500°C (2732 F) with molybdenum retort
  • Hot zone size of 8″ diameter x 10″ high (203 mm x 254 mm)
  • Automated lift and clamp mechanism for bell jar chamber
  • Hydrogen operation with integrated safeties
  • Retort allows removal of volatile substances while improving thermal uniformity
  • Space-saving design


The furnace chamber is cylindrical in shape and is manufactured from double-walled stainless steel. The chamber is welded and electro-polished for vacuum integrity and appearance. The whole chamber including shields and heating elements are lifted by an electric actuator to give full and easy access to the loading area.

There are two instrumentation feed through ports (for thermocouples) and a gas-ported quartz sight window is provided for viewing.

The hot zone is manufactured from tungsten and molybdenum, with multiple layers of shields to minimize heat loss. A molybdenum retort lifts up and down with the Bell Jar. The retort serves two purposes, it isolates and protects the hot zone from volatile process by-product, and it increases temperature uniformity of the heated zone.

Power connections to the heating elements are on the top cover of the chamber and are water cooled. The water-cooled flexible power cables bring power to the heating element.


This furnace system was designed to operate in vacuum, partial pressure and several gas environments. such as Hydrogen,  Argon or Nitrogen. The maximum positive pressure is 5 PSIG. A relief valve, pressure gauge and a Hydrogen burn-off are located on the top chamber of the furnace body. A second Hydrogen line is located on top of the molybdenum retort. A safety Nitrogen purge line valve opens automatically in case of an alarm condition.

A Hydrogen Gas Manifold System, pressure switch, hydrogen flow meter, explosion-proof solenoid valve, blow-off port and a gas igniter system are all standard components to meet safety and NFPA requirements.


The standard pumping system evacuates the furnace into the 10-3 Torr vacuum range. The purpose of this pumping system is to quickly remove oxygen from the inside of the furnace and allow a furnace run in vacuum, or to back-fill with your desired gas process and run in an oxygen free environment.

The vacuum system contains the following components:

  • A Rotary Vane Pump with an exhaust filter.
  • A electro-pneumatic vacuum valve to isolate the chamber from the pump for operation in process gas.
  • A vacuum relief valve (back to atmosphere) is provided for the purpose of releasing the pressure or to conveniently leak check the system.
  • Electrical components to monitor and operate the pumping system.
  • A Vacuum Gauge Controller indicates the furnace pressure using a Capacitance Diaphragm Gauge (CDG) and/ or a vacuum thermocouple gauge.
  • Power to the heating elements is interlocked with the vacuum level in the chamber if a vacuum run is being made.


Hot zone power is supplied by a three phase SCR-controlled transformer. This Power Supply is designed to accommodate high ramp rates to the maximum operating temperature of 2000°C.

All required circuit breakers, contactors, electrical components and furnace controls are housed in one enclosure. The system meets all applicable NFPA Electrical and safety codes.


With the basic control package, temperature control is established with a Eurotherm temperature controller. The furnace temperature is measured using a two-color optical pyrometer and a type “C” thermocouple.

The TC controls hot zone temperature from room to 1000°C. The pyrometer will then take over control from 1000°C to 2000°C. At the change-over, the thermocouple will automatically be retracted into the shielding, protecting it from overheating. This retractable TC is sealed with metal vacuum-tight bellows, eliminating the need for sliding seals.

The vacuum gauge, vacuum controller and control panel components allow monitoring and operation of the vacuum system.

The operation of the furnace is made simple and requires only minimal operator interaction, but still allows supervisors or technical personnel to re-configure and further customize the furnace operation.

The optional computer HMI control system unifies all control to one easy-to-use PC interface, see our option page for more details.


The water system is designed to adequately cool all the furnace components so exterior surfaces will not exceed 120 F (45°C). To insure proper flow, a water flow interlock is installed indicating flow and allowing power to be applied to the heating elements when sufficient flow is present. In the event water flow is interrupted for more than 5 seconds, power is disconnected to the heating elements.

The water manifold has several circuits supplying water to the various parts of the furnace. Each one of these can be manually adjusted to allow each circuit the proper amount of flow to minimize water flow yet provide proper cooling.


Power: 45 kVA, 400-480V/3/50-60 Hz (other voltages available)
Water: 7 G.P.M. (27 lpm) @ 70 F (20°C) and 50 P.S.I.G. (3.4 bar)
Process Gas: H2, N2, Ar, He, 30-60 lpm @ 40 P.S.I.G. (2.75 bar)
Compressed Air: 60-90 P.S.I.G. (4.1 – 6.2 bar)filtered.

Available Options for our bell jar furnace:

  • Annealing
  • Brazing
  • Binding
  • Ceramics Processing
  • Compound Synthesis
  • Debinding, Degassing, Dewaxing
  • Diffusion Bonding
  • Fiber Drawing (Graphite, SiC)
  • Nano-technology
  • Powder Metallurgy
  • Reaction Bonding
  • Sintering

Coming soon!