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Gas Catalytic IR Refurbishing ServicesVulcan offers* a rebuild / refurbishment program for all industrial catalytic Heaters and a rebuild / refurbishment program for your existing IR Oven(s)
Troubleshooting catalytic IR ovens Problem. A powder coater wants to know what to look for to increase the efficiency of his existing catalytic infrared (IR) oven. Since buying the oven several years ago, the coater has decreased line speed. He now wants to speed up production again, but keep his original oven. Solution. Understanding the principle of how IR heats objects is key to understanding how improvements can be made to a catalytic oven. This understanding can be broken down into two areas: How the catalytic heaters operate and what happens to the IR once it leaves the heater surface. How catalytic heaters operate. The heaters provide heating energy through converting natural gas or liquid propane (LP) via catalytic reaction that should produce a maximum heater surface temperature of 800°F to 1,000°F. Reaching this temperature depends on a number of factors. For one, the catalyst must be intact and dust free (no residue from burned powder). This applies mostly to heaters on the bottom of the oven. Do not under any circumstance use a vacuum cleaner or an air line to remove dirt from the heaters. This simply removes the catalyst and stops the formation of heat. To eliminate dirt, first make sure powder is contained within the powder booth and can’t migrate towards the oven entrance. The oven exhaust may be excessive, pulling powder into the oven. Reduce the exhaust if necessary. In addition, have heaters that are covered with overspray repacked with a new catalyst pad. This will bring them back to full strength. Remember, once the catalyst stops reacting due to overspray or simply old age, nuisance system shutdowns can occur from the cooling down of safety thermo switches, causing lost production times. As a general rule, the equipment to preheat the oven and deliver gas to the heaters requires little or no maintenance. Any degradation of oven performance is usually heater related. Every catalytic heater has an electrical heating element. If this fails, the oven won’t start. Again, a repack of the offending heater will bring it back to life. What happens to the IR once it leaves the heaters. Assuming all the heaters are working correctly, the next area to study is what happens to the IR once it leaves the heaters. IR has the same properties of light; that is, it travels in straight lines at the same speed. It continues in motion until it’s either absorbed or reflected. In a perfect world, all the IR would be absorbed by the powder on the part. In practice, as much as 50 percent of the IR misses the part. It’s this energy that needs to be redirected and kept active within the part window until it’s absorbed by the coated part. For this to happen, reflectors must be kept clean and free of any dirt or powder; otherwise, the reflectors become absorbers and get hot. This is directly opposite to their designed function--to reflect IR and stay very cool. To correct this, simply line the dirty reflectors with aluminum foil. Repeat this monthly as a preventive maintenance function. Many catalytic IR ovens simply have no reflectors, sometimes called “heaters on a stick.” In these cases, the 50 percent of IR that isn’t absorbed by the parts leaves the part window and is lost forever, heating up the inside of the oven exterior. IR ovens must have a fully reflected interior for maximum efficiency. If your oven has areas where IR can escape, fabricate galvanized sheet metal to fit between the heaters. This will greatly increase your heating efficiency. Example of the “heaters on a stick” approach to oven building, where 50% of the Infrared escapes to the back of the oven and is lost for ever. This escaping IR heats only the back of the inside of the oven, requiring insulated oven walls. 
Vulcans’ approach is to contain the IR, fully reflecting it back into the part window to be absorbed by the coated part. Net result is lower gas consumption and faster heat up times as compared to the “heaters on a stick” oven builds, 
Call John Martin at
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Vulcan Catalytic Systems, Ltd. | 300 Highpoint Ave., Portsmouth, RI
02871 | 401-683-2070 Email: jmartin@vulcan-mdf.com |
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