TUNNEL OVENS

 SEALS

• THE ENTRY OF THE TUNNEL OVENS WOULD BE CLOSE SILHOUETTED TO THE MAXIMUM WORKLOAD AND WOULD INCLUDE HEAT SPILLAGE CONTROL BY MEANS OF A RECIRCULATING FAN-POWERED SYSTEM.
• THE AIR SEAL INCLUDES DIRECTIONAL DAMPER BLADES TO ALLOW A SMALL OUTFLOW AT THE BOTTOM OF THE SILHOUETTE TO COUNTERACT THE NATURAL TENDENCY FOR AN INRUSH OF COLD AIR AT THE BOTTOM OF THE SILHOUETTE.

BLEED FAN

• 10% OF THE RECIRCULATED AIR IS EXHAUSTED TO ATMOSPHERE TO REMOVE ANY RESIDUAL SOLVENTS, WHICH MAY ACCUMULATE AND CAUSE AN EXPLOSION. THIS CAN OCCUR WITH POWER PAINT AS WELL AS WET PAINT. WE FIT AN ADDITIONAL BIFURCATED FAN TO EXHAUST THIS VOLUME OF AIR.
• THE BLEED DUCT IS TO ATMOSPHERE AND COMPRISES A MANUAL DAMPER AND DISCHARGE AT HIGH LEVEL. DISCHARGE THROUGH EXISTING ROOF PENETRATION IF POSSIBLE.

CONTROL PANEL

A SINGLE CONTROL PANEL WILL CONTROL ALL THE ELECTRICAL FUNCTIONS OF THE DUALCON SYSTEM AND CONTROL ALL THE TEMPERATURES THROUGH PLC ANALOGUE INPUTS AND OUTPUTS TO THE BURNERS AND TEMPERATURE PROBES. THIS WOULD THEN BE CONTROLLED VIA A SCREENED PANEL ON THE DOOR WHERE THE SYSTEM CAN BE MONITORED AND START AND STOP THE SYSTEM. THERE WOULD BE A MINIMUM OF THREE PAGES CONTROLLING EACH AREA OF THE INSTALLATION.

THE OPERATING SYSTEM FOR TUNNEL OVENS IS AS FOLLOWS:

• ON PRESSING THE START BUTTON THE PURGE CYCLE WILL START. IN THIS CYCLE THE RECIRCULATION FANS AND BLEED FAN WILL RUN FOR A VARIABLE TIME (NORMALLY APPROXIMATELY 2 MINUTES). THE PURGE CYCLE WARNING LIGHTS WILL BE ILLUMINATED AT THIS TIME. THE REQUIRED TEMPERATURE SHOULD BE SET DURING THIS PERIOD.
• AT THE END OF THE PURGE CYCLE THE PURGE CYCLE LIGHT WILL EXTINGUISH AND THE BURNERS WILL START THE FIRING CYCLE. THE BURNERS WILL FIRE UNTIL SET POINT TEMPERATURE IS REACHED AND THEN TURN DOWN TO A LOW HOLDING FLAME.
• THE EMERGENCY STOP BUTTON SHOULD BE USED ONLY IN EMERGENCIES AND NOT FOR STOPPING THE OVEN NORMALLY.

Oven Wall design : Standard Galvanised inverted tray packed with high density Insulated slab 100kg.

Thickness 100 mm / 130 mm : (Cladding Alternative with external wall powder coat finish please ask)

TUNNEL OVENS – WALLS

• TUNNEL OVENS ARE CONSTRUCTED FROM COMPOSITE PANELS COMPRISING A 1.2MM THICK STEEL OUTER SHEET, POWDER COATED TO CUSTOMERS SPECIFIED COLOUR (BS 18E53 AS STANDARD), AND AN INNER SHEET OF 1.2MM ALUMINISED MILD STEEL (ALUDIP), ALUDIP IS LESS POROUS THAN GALVANISED STEEL AND PREVENTS CORROSION CAUSED THROUGH CONDENSATION DUE TO CONSTANT HEATING AND COOLING OF THE OVEN. THE PANELS ARE INSULATED WITH A CORE OF 100MM THICK MINERAL WOOL INSULATION. THIS GIVES A COMPOSITE THICKNESS OF 100MM OF INSULATION THAT PREVENTS LARGE HEAT LOSS. THE INNER AND OUTER SHEETS ARE JOINTED USING A CNC MACHINED JOINT DESIGNED TO MINIMISE HEAT TRANSFER FROM INNER TO OUTER SHEETS. THE PANELS HAVE A RIVETED CONSTRUCTION.
• EXTERNAL WALL PANEL JOINTS ARE SMOOTH, WITH INTERNAL JOINTS BEING BOLTED, STUFFED WITH INSULATION, AND CAPPED ON SITE.
• WALL PANELS AND JOINTS ARE COOL TO TOUCH WHILST THE OVEN IS IN OPERATION.

TUNNEL OVENS – ROOF

• TUNNEL OVENS ROOF PANELS HAVE EXPLOSION RELIEF HOLES THEN ARE COVERED WITH 2 LAYERS OF 50MM THICK MINERAL WOOL INSULATION AND COVERED WITH ALUMINIUM FOIL TOP AND BOTTOM. THIS CONSTRUCTION FORMS THE EXPLOSION RELIEF AREA SO THAT IN THE UNLIKELY EVENT OF AN EXPLOSION IT WILL BE VENTED VERTICALLY PREVENTING INJURY TO PERSONNEL.

DUCTWORK

• DISTRIBUTION DUCTWORK WOULD BE MANUFACTURED FROM ALUMINISED MILD STEEL OF FLANGED CONSTRUCTION CONFORMING TO BEST MANUFACTURING PRACTICE. FLANGED JOINTS WOULD BE PROVIDED FOR EASE OF SITE ASSEMBLY AND MAINTENANCE, THE WHOLE TO BE ADEQUATELY SUPPORTED. BALANCE DAMPERS FITTED ALONG THE LENGTH TO PROVIDE UNIFORM HEAT DISTRIBUTION.
• EXHAUST DUCTWORK WOULD BE MANUFACTURED FROM GALVANISED MILD STEEL COMPLETE WITH WEATHER PROTECTION BUT NOT SEALED.
• AIR DISTRIBUTION DUCTWORK IS FULL LENGTH, LOCATED AT FLOOR LEVEL TO AND IS FITTED WITH ADJUSTABLE BALANCE DAMPERS ALONG THE FULL LENGTH. ADDITIONAL FRONT / BACK MAIN OVEN BALANCE CONTROL DAMPERS
• AIR COLLECTION DUCTWORK IS FULL LENGTH, LOCATED AT HIGH LEVEL AND IS FITTED WITH ADJUSTABLE BALANCE DAMPERS ALONG THE FULL LENGTH.

HEATING EQUIPMENT

THE HEATING SYSTEM WOULD COMPRISE A SINGLE END MOUNTED VERTICAL HEATER TOWER ARRANGEMENT, WITH ONE BURNER AND ONE RECIRCULATION FAN. THE HEATER BOX IS CENTRALLY LOCATED IN THE END OR SIDE WALL TO PROVIDE AN EVEN TEMPERATURE DISTRIBUTION AND CONTROL. THE DIRECT GAS-FIRED HEATER UNIT INCORPORATES A FORCED DRAUGHT BURNER COMPLETE WITH FLAME AND AIR FAILURE PROTECTION, AUTOMATIC IGNITION, AND THERMOSTATICALLY CONTROLLED SOLENOID VALVES.

AN AIRFLOW SWITCH WOULD BE FITTED IN THE DISTRIBUTION DUCT AND EXHAUST DUCT TO SHUT DOWN THE OVEN HEATER IN THE EVENT OF CIRCULATION OR EXHAUST FAN FAILURE. TEMPERATURE CONTROL

TO CONTROL THE TEMPERATURE OF TUNNEL OVENS, WE WOULD PROVIDE ONE OFF ELECTRONIC CONTROLLER. THE CONTROLLER WOULD HAVE THE FACILITY FOR SET-POINT TEMPERATURE CONTROL. TEMPERATURE SENSING WOULD BE BY A THERMOCOUPLE LOCATED IN THE OVEN.

AIR RECIRCULATION

AIR IS RECIRCULATED IN TUNNEL OVENS WITH ONE OFF CENTRIFUGAL FAN FITTED WITH CASING TO IMPROVE EFFICIENCY. AIR IS COLLECTED AT HIGH LEVEL IN THE ROOF OF THE OVEN AND IS DISTRIBUTED AT LOW LEVEL THROUGH DUCTING FITTED WITH SLIDE AND BALANCE DAMPERS. THE DAMPERS ENSURE THAT AN EVEN TEMPERATURE CAN BE ATTAINED THROUGHOUT THE OVEN. THE HEATING DEVICE IS MOUNTED IN THE RECIRCULATED AIR STREAM SO THAT THE RECIRCULATED AIR COLLECTS THE HEAT.

WE INCLUDE FOR AN ADDITIONAL DISTRIBUTION DUCT INTERNAL ADJUSTABLE DEFLECTOR TO CONTROL HEAT FLOW TO THE FRONT OF THE OVEN (THE ‘COLD’ PRODUCT DRAWS THE HEAT DOWN AT THE START OF THE OVEN, SO MORE HEAT IS REQUIRED).

THE AIR RECIRCULATION FANS WILL BE DIRECT DRIVE MULTIVANE, WITH OILED IMPELLOR.

WE ALSO INCLUDE FOR FULL LENGTH AIR COLLECTION DUCT, AGAIN FITTED WITH ADJUSTABLE DAMPERS SO WE CAN COLLECT AIR WHERE REQUIRED (TYPICALLY AT THE ENDS OF THE TUNNEL OVEN TO CREATE A TABLETOP TYPE HEAT PROFILE).