Products Finishing

SEP 2018

Products Finishing magazine is the No. 1 industrial finishing publication in the world. We keep our readers informed about the latest news and trends in plating, painting, powder coating, anodizing, electrocoating, parts cleaning, and pretreatment.

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30 SEPTEMBER 2018 — POWDER COATING humidity and temperature uniformity. The amount of duct needed for air supply or intake will also affect costs, as will the piping for chilled or hot water running to the HVAC. Other considerations are coolant gases, the location of the compressor relative to the HVAC, as well as the weight of the equipment vs. the capacity of the building's roof. The power supply to the HVAC equipment and control wiring will also affect costs. And don't forget the footprint of this equipment; it can be as much or more square footage than the spray booths. Budgets and Reducing Costs There are ways to lower costs associated with HVAC. For example, is there already chilled water, or hot water or steam in the facility with extra capacity for the new system? Budgetary considerations include: • Simple dehumidification, which involves cooling to condense water from the air and then reheating to 70°F/80°F for painting at $10 to $20 per cfm. So the unit/system cost for 20,000-cfm air volume would be $200,000 to $400,000, not installed. • Re-humidification would add another $10 to $20 per cfm ($200,000 to $400,000). This is different from dehu- midification, where it is hot and dry and water evapo- rates quickly and easily. This is for cold and dry climates, where you need to heat the water (boil it/turn it to steam) and put it into the airstream properly, so it doesn't rain in your booth. There are exceptions and conditions that impact these cost savings: A smaller-cfm system can cost disproportionally more because the per-cfm "rule" is skewed and a large system has more cfm to dilute the dollar figure. There are many reasons systems cost so much, including indirect-fired burners, boilers, chillers and rehumidification. For boilers/chillers, additional costs include piping, tanks, water treatment, freeze protection, modifications to support the weight of units and weight of water (8.64 pounds per gallon), to name a few. All of this equipment has a fairly large footprint, and it can be located some distance from the booth it is supplying. A note on freeze protec- tion: If the installation climate for a chiller is cold, a shop must add freeze protection. This protects the units from burst pipes and coils, but also it takes away capacity, which means a shop may have to upsize the unit capacity to allow for the proper amount of heating/cooling. This, of course, effects the unit's price. There are ways a facility can reduce costs while meeting specifications. One way is by recirculating the air of the spray booth. For 20,000-cfm exhaust, you can recirculate 80 percent (16,000 cfm) and exhaust 20 percent (4,000 cfm). This saves considerable money, since 4,000 cfm times $40 per cfm equals $160,000; the worst-case $800,000 is reduced by $640,000. So recirculation, if allowed, can greatly reduce costs. The cost of the booth will be more, but is minimal compared to the saving achieved. Any system will require controls, and this, too, plays into the cost structure. The control system must sense the temper- ature of the incoming air and its humidity content, and then supply more cooling or heat to the system, in addition to monitoring the conditioned air going to the spray booth and making adjustments. Booths are run by a control panel, which measures humidity and temperatures. Image courtesy of Whesco Group. The amount of duct needed for air supply or intake, such as with this recirculation AMU, will also effect costs. It's critical to have the correct climate conditions.

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