DAVID WEISMAN, L.L.C.
203-322-9978 HEAT PROCESSING SOLUTIONS FOR INDUSTRY TM
flat wire mesh belt horizontal
conveyorized infrared oven system
overhead conveyor gas catalytic infrared
with air recirculation preheat & cure oven
overhead conveyor gas fired
hot air convection
bottom up vertical air flow
preheat & cure oven
heavy duty gas fired hot air
convection batch oven
heavy duty electrically heated hot air
convection walk in batch oven
enhanced horizontal conveyorized
gas catalytic infrared oven system
with top and bottom heating
preheat and cure, electric infrared
with air tunnel heaters
overhead infrared preheat
boost gel and cure oven
arched paper, film, foil and textile
infrared web dryer
fast response, clamshell tunnel
parallel chain conveyor infrared oven
horizontal fast response electric
infrared preheat continuous
coil & web clamshell oven
infrared panel heater
enhanced heavy duty gas fired
hot air convection batch oven
multipass hot air convection
wire, cable and rope dryer
two zone fast response
clamshell tunnel heater
portable embedded element
high energy density
clamshell tunnel heater system
fast response infrared heaters
and controls powder coat
preheat gel booster
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FAST RESPONSE ELECTRIC INFRARED PREHEAT OVEN
ELECTRIC AND GAS INFRARED BOOSTERS
HORIZONTAL INFRARED AND HOT AIR CONVECTION CONVEYOR OVENS
INDUSTRIAL WALK IN BATCH OVENS
ELECTRIC AND GAS INFRARED HEATERS
NEMA CONTROL PANELS
DESIGN AND MANUFACTURE OF INDUSTRIAL WALK IN BATCH OVENS
INFRARED AND HOT AIR IMPINGEMENT CONVECTION WEB DRYERS
FOCUS ON PAINT AND POWDER COAT OVENS
FOCUS ON CONVEYORIZED PROCESS OVENS
FOCUS ON WEB DRYERS
FOCUS ON BATCH PROCESS OVENS
FOCUS ON INFRARED OVENS
FOCUS ON INFRARED HEATERS
FEATURES KEY TO A QUALITY INDUSTRIAL HOT AIR CONVECTION OVEN © 2009 DW
There are many factors that differentiate the design and manufacture of a quality industrial hot air convection oven from a poor quality or low end system including: proper airflow, use of properly temperature rated components, proper sizing of air recirculation (to get a reasonable air velocity and number of air changes per minute) and burner components, a powered exhaust system, use of oven material and construction for energy efficiency and longevity, oven workmanship and complete solution, and detailed operation and maintenance manual documentation with preventative maintenance recommendations to name a few.
Gas fired and electrically heated hot air ovens are available with a very broad range of quality. Does the industrial oven you are considering offer you the performance and quality you are looking for so you can focus on growing your business, instead of just focusing on just keeping your production equipment running?
Proper airflow starts with the use of ductwork to move air well in the oven interior. The type of airflow will take into account the type of products you are processing, and how you are racking or processing them. In many walk-in style batch and overhead conveyor oven systems a combination air flow, or vertical airflow is the best choice from a uniformity of temperature throughout the work chamber perspective. Perhaps your parts to be heated or dried or cured are to be processed on horizontal shelves which will block vertical airflow. In this case the best choice will be a horizontal airflow systems. Low end systems to not offer internal ductwork, or options, they blow air from the top of the oven and 3hope and pray” the heat will get where it needs to. This becomes more and more important as the nominal oven process temperature(s) increase. Not as important at 200 deg F as it is at 400, 600, or 800 deg F!
Properly temperature rated and sized blowers are an expensive part of an oven systems material cost. Many low end manufacturers or distributors underspec the temperature rating and undersize the CFM and HP on blowers to save material costs in manufacture. Quality convection ovens that are rated for 500 deg F continuous operation, utilize blowers that are rated from 550 to 650 deg F. Low end manufacturers rate their ovens to 450 deg F or less to go with less expensive blowers. Also convection ovens work well in terms of heat transfer when they have higher air velocities and air changes per minute. Quality systems use blowers with more CFM and HP, and smaller burners for improved or optimized energy efficiency and proper air purge. Low end systems quote larger burners (as this waste in extra energy will cost the end user perhaps significantly but is essentially free to the oven builder), and smaller blowers as this is where the $ are.
Powered exhaust systems are important to properly exhaust products of combustion in a direct gas fired system, as well as properly exhaust solvents or VOCs present in the oven chamber. However to cut corners and cost to manufacture, poor quality oven systems do not include a powered exhaust, merely non-powered exhaust off of one of the ports on the air recirculation blower. This can be acceptable in certain situations, but it is a cost cutting method “red flag", and only offered as a way to appear to be more attractive to a buyer. It is NOT the signature of a quality oven system!
Different types of materials in terms of interior and exterior and insulation can be used for the oven shell and the internal ductwork if it is present at all. Quality systems employ aluminized or stainless steel on the interior. Steel thicknesses should be used to minimize and eliminate warpage due to high temperatures over time. There are several types of insulated panel construction that are acceptable, however, tacked welded, pop riveted in combination with tek screws work well. Tek screws alone are note acceptable as over time from expansion and contraction the screws work their way out, leaving gaps in the oven shell and creating heat loss. Also, quality systems are self supporting. Low end systems often require a plate or insulated floor to help hold the structure together. There are exceptions but this is a good general rule. While insulation density and thickness are important for energy savings and to keep external surface temperature safe to the touch, insulating material should be used that affords longevity, where the insulation will not sage over time.
Oven workmanship in terms of wiring, piping, and overall finishing work is critical to determining if you are getting a quality piece of equipment. Pictures ARE worth a thousand words. Look closely at what you are evaluating. Does the system offer a complete solution are important items such as control panel lockable disconnect switch and/or door limit switches left out of the proposal to make the price look more attractive? Quality systems include or at least mention EVERYTHING you will need to the best of their ability.
Documentation as is customer service is very important. As a minimum, you should expect to receive a operation and maintenance manual with a start up procedure, notes on troubleshooting and recommendations on preventative maintenance. A complete parts list and recommended spares list should be readily available as well.
Carefully evaluate what a company is offering in order to determine if the industrial oven you are considering will provide you with the performance and quality you are looking for so that you will make a successful decision!
Based on the broad range of gas fired and electrically heated hot air oven quality that
are available, it is highly recommended that you find an experienced company (such as ours) that manufactures hot air convection ovens as well as infrared oven systems and whose primary interest is in finding and recommending the best solutions(s) for your process improvements and new projects, no matter how small or large they may be.
Written By: David Weisman, September 18, 2009
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URBAN MYTHS WITH REGARD TO INFRARED HEATERS AND OVEN SYSTEMS © 2008 DW
IS INFRARED RIGHT FOR YOUR PROCESS © 2008 DW
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