Current Inventory >  Watkins-Johnson Belt Furnace

Watkins-Johnson Controlled Atmosphere Conveyor Furnace

Model 8CR-55(H)       Serial Number 3472

Price: $8,000.00

1. Scope:

a.      This specification shall cover the manufacture of a controlled atmosphere conveyor furnace capable of operating to 600^o C with either hydrogen, hydrogen/nitrogen mixtures, hydrogen/argon mixtures, or with an air, nitrogen, or other typical non-combustible atmospheres. This specification shall include all items necessary to deliver a complete furnace ready for installation and connection to utilities.

2. Specifications:

a.      Temperature:

                                                  i.            Peak Temperature: The furnace shall be capable of continuous operation to 600^o C in the peak zone.

b.      Muffle

                                                  i.            Muffle: A nominal 4” high x 8 Ύ” wide Type 309 stainless steel muffle shall be provided.

                                                ii.            Cooling Section:  A nominal 4” high x 8 Ύ” wide x40” long water-cooled muffle of Type 309 stainless steel, followed by 16” of forced air cooling, shall be provided. The air cooling hood shall be located on the exit table.

c.      Atmosphere Control:

                                                  i.            Atmosphere Inlets: The furnace shall provide for the use of an air or nitrogen atmosphere. Atmosphere inlets shall be located between Zones 5 and 6 and between Zone 6 and the cooling section. Two flow meters calibrated for nitrogen shall be provided.

                                                ii.            Flux Removal: The furnace shall be designed to provide maximum removal of evaporated flux and to prevent flux fumes from escaping into the room. A vent hood shall be located at the entry of the furnace chamber. Vent shall terminate in a 3” diameter stack.

                                              iii.            Baffles: Atmosphere and temperature control baffles shall be located on each side of Zone 6.

                                               iv.            Flapper Door Assembly: The furnace shall be provided with an exit flapper door assembly.

d.      Conveyor System:

                                                  i.            Conveyor Belt: The furnace shall be provided with a nominal 8” wide conveyor belt of Type 304 stainless steel (balanced spiral 60-50-20, or equivalent).

                                                ii.            Conveyor Speed: The furnace shall be provided with a variable speed conveyor drive system capable of control between 1-12 inches per minute. Tachometer feedback closed-loop control shall be provided. Speed control accuracy shall be +/- 2% over the full range.

                                              iii.            Drive System: The conveyor drive system shall provide positive traction and belt alignment throughout the furnace and shall be controlled through a DC motor.

                                               iv.            Conveyor Belt Return: The conveyor belt return shall be covered with Arguto Hi-D, or equal.

e.      Furnace Chamber: The furnace chamber shall be divided into the following zones (typical furnace shown in parentheses):

f.        Temperature / Power Controls:

                                                  i.            Thermocouples: One Chromel / Alumel (ISA Type K) thermocouple shall be provided in each of the six controlled heat zones and shall be located under the muffle. All thermocouples shall be individually removable from the bottom of the furnace. Positions are provided for two additional thermocouples in each zone for monitoring or overtemperature control.

                                                ii.            Process Control: The furnace shall be provided with a multi-channel microprocessor based temperature controller. The controller shall provide three-mode temperature control with keyboard entry of setpoint, power level, proportional band, reset, rate, and high-low process alarm settings for each individual zone. Belt speed control shall be accomplished through the Model WJ-988 Microprocessor Controller. Up to eight different profiles (“recipes”) can be stored and recalled through the keyboard. An alphanumeric one-line readout is provided for belt speed, temperature, setpoint, power level, proportional band, reset, rate, and high-low process alarm settings for each zone.

                                              iii.            Power Controls: Power to the heating elements shall be supplied through five zero-firing SCR power modules.

                                               iv.            Function Controls: The furnace shall be provided with On / Off switches and indicator lights for the following functions:

1.      Control Power

2.      Conveyor Power

3.       Alarm Silence

4.      Element Power

5.      Air Cooling

6.      Water Fail

g.      Heating Elements: The furnace shall be provided with high temperature alloy heating elements of Tophet 30, or equal. Elements shall be helically wound in shaped ceramic back plates. Elements shall be mounted above and below the muffle.

h.      Safety Features: The furnace shall be provided with the following safety features, which shall be equipped with audible and visual alarms, alarm silencer, and reset switch, when applicable.

                                                  i.            Thermocouple Break Protection: Thermocouple break protection shall be provided on temperature controllers.

                                                ii.            Water Failure: A flow switch shall be provided to shut off heater element power in the event of water failure.

3. Construction:

a.      Frame: The furnace shall be constructed on a welded square-tubular steel frame. Leveling pads shall be provided.

b.      Panels: The furnace shall be enclosed with removable panels.

c.      Insulation: Johns-Manville Superex installation, or equal, shall enclose the heated portion of the muffle.

d.      Loading / Unloading Tables: 26” long loading and 36” long unloading tables shall be provided. The table surfaces shall be stainless steel. Approximately 20” of exposed belt shall be provided at the entry and 18” at the exit end of the furnace (measured to centerline of pulley).

e.      Dimensions: The furnace shall have the following approximate overall dimensions:

                                            i.            Length: 15.6’

                                          ii.            Width: 41”

                                        iii.            Height: 68”

                                         iv.            Conveyor Belt Height: 33”

                                           v.            Working vertical clearance above conveyor belt shall be 3” nominal (exclusive of baffles).

f.        Shipping weight: Approximately 1800 pounds.

4. Utilities: The following utilities shall be provided by the customer:

a.      Electrical: 20 KVA maximum connected load (8 KVA typical operational), 208 / 230 volts, three phase, 50 / 60 hertz.

                                            i.            Note: Main fused disconnect switch shall be provided.

b.      Water: 60 GPH @ 50 PSIG.

c.      Atmosphere: Air or nitrogen, 300 SCFH maximum @ 20 PSIG.

d.      Utility Connections: Power, atmosphere inlet, and water connections shall be located at the exit end of the furnace. The exhaust system shall terminate in a 3” diameter stack located at the entry end of the furnace.

                                            i.            Note: Supply requirements in Section 4 are recommended supplies and may exceed actual furnace requirements.

5. Documentation: Manual included.