Friday, 21 March 2008 14:57

The Benefits of Direct Air Acceleration: Garmat’s Solution

Written by with Johan Huwaert, GM, Garmat USA
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A mini-interview with Johan Huwaert, General Manager, Garmat USA

If you talk to Southern California shops who have converted to waterborne you’ll hear mention of “Garmat-type fans”, or just “accelerator fans.” These are high velocity “fans” that move air, but how do they work specifically to flash waterborne? We asked Johan Huwaert, Garmat USA’s general manager, to explain the process.

Why is this technology important in the flashing of waterborne paints?
Waterborne paint needs a higher velocity airflow to “accelerate” the drying process. Accele-Cure utilizes aluminum blade propeller fans, which are designed to focus air flow at a faster velocity directly over the vehicle. By breaking the microclimate around the paint surface, the water or solvent is extracted more quickly, accelerating the drying process. This ultimately results in a substantially quicker flash time. Testing has proven that Accele-Cure flashes paint more quickly for both waterborne and solvent type paints.

What does it increase, air volume or air velocity?

There is a big confusion in the market between CFM, Cubic Feet Per Minute (measuring volume of air) and air velocity (measuring the speed of air).  A booth mechanical delivers a certain volume of CFM. This is almost always a constant.

With Accele-Cure, the “accelerators” pull the air from the ceiling filters and funnel it towards the center of the paint booth.  The area through which air passes is reduced. When you’re reducing the area through which the air passes and your CFM is held constant, it means that your airspeed is accelerating.  So we’re not increasing the CFM in the booth, but we’re dramatically increasing airspeed or velocity.  

So you’re getting increased air velocity, but how do you keep the air clean?

The Accele-Cure system accelerates the air that originates from the booth’s plenum and substantially increases downdraft airflow around the contours of the vehicle. Since the accelerated air originates from clean, filtered plenum, contaminants are not introduced.  The system increases the velocity of the existing downdraft airflow patterns significantly over all areas of the vehicle, dramatically decreasing drying time.

      The system has been found to drastically reduce flash times of solvent-based and waterborne paints. A benefit of Accele-cure is that we can customize the desired air speed, from low to high based on each individual situation—we can exceed the capacity of the booth mechanical because each blade has a capacity of 8000 CFM.

    A typical booth has three to four waterborne drying units depending on the length of the booth so you can get easily 24,000 to 30,000 CFM in your booth.  When we set up the Accele-Cure system, we use smoke tests to check circulation. If the air should start moving back up the walls, it means that we have overpowered the booth mechanicals.   If the fans are set to stay just below that threshold, the system is optimized.  For each booth, Accele-Cure needs to be taken up to the maximum so the capacity of the booth can be adjusted accordingly.

    When used during the “dry” cycle, the Accele-Cure system draws air towards the center of the booth and accelerates the air delivered from the plenum for more efficient flashing of the paint.


Were these accelerators originally designed for waterborne or solvents?

Both. They were designed to increase air speed. They work very well for both waterborne and solvents based paints. We have found that during the spray mode, Painters run them at very low speeds. During the bake cycle, heat rises naturally, so when the unit is first turned on in bake, the heat lingers at the top. The system compensates and drives the heat down.  The heat is being taken from the top of the booth and it is being concentrated where you need it. During the bake cycle, the system transfers heat to the car body faster and more uniformly resulting in a significantly reduced cycle time. Accele-Cure benefits all stages of the paint process and the speed programmable on all cycles for maximum performance.


How do you decide whether or not this is appropriate for any particular booth?

Garmat’s Accele-Cure System can be installed or retrofitted to almost any kind of booth including prep stations and larger industrial booths.

    Ideally, to optimize the operation of Accele-Cure, you would want to install it in a downdraft or a side draft booth.  We have different configurations depending on the size of booths and individual requirements. The normal setup would be three units in a 27’ foot booth and four in a 31’ booth.


Is the filtration the same in the booth?

We use exactly the same filters.  In some booths we change the filter racks to accommodate for filter support beams, so we have a landing place for the bearing. Some booths have one large ceiling filter, for these booths we have a retrofit available.


All of the operations of the accelerating system are independent of heat and humidity?  

Correct. We do not tie into existing mechanicals because that makes it complicated and problematic. It’s a completely independent operation from the booth mechanical.


What would it cost to put in three to four units?

A 3–4 unit installation would typically run below $10,000, which pays for itself very quickly because you’re decreasing your cycle time in spray , bake and cool down . If you decrease your bake cycle you’re saving time but you are also using less energy.  (If  your bake cycle time would be say 30 minutes it’s now 20 minutes, meaning you’re only running 20 minutes of electricity and gas for the same length of time.  And of course also there’s the labor factor—less time there too.)

    We now provide systems with an in-booth control so that the painter doesn’t have to leave the booth to operate the system.  In truck booths and tunnel booths we install eight or ten units. In these booths we regulate the airspeed from inside the booth to obtain optimal  performance.


Are these accelerators being installed in the new booths?

Almost all new Garmat booths that are currently shipping are equipped with Accele-Cure systems.


Garmat USA has several distributors in the West, organized by county. Find distributors at www.garmat.com, by filling out a contact form, or by phone: 800-442-7628.

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