What are you seeing and recommending to help shops improve their air management?
The old thought was we refrigerate the air to lower the moisture in it and when you’re running, the air comes out of the compressor at 180° through a refrigerated system the air drops down to 45-ish degrees. You need a desiccant unit to get the moisture down below 10%.
We like Sullivan Palatek compressors, because they have the filtration and the desiccant units built in. You’ve got clean air going right through the body shop. No moisture whatsoever. The desiccant comes in the form of pellets, but it is in a throw-away container, like an oil filter. You just unscrew it and dispose after about three years.
A desiccant compressor is far superior to a refrigerating unit. If you’re not drying your air, you’re putting moisture into the system through the hand blowers onto the car. If you get a dehumidifier or a desiccant, it’s going to dry quicker. A lot of body shops have desiccant units outside the booth. If you’ve got a piston compressor without filtration you’re putting dirty air into those blowers and got to frequently change the desiccant at $60–100 a go.
You want your filters upstream so you stop oil vapor from polluting the desiccant. We approached Sullivan Palatek with to design the compact units with tank, compressor, and the desiccant unit. Most of the compressors we’re selling right now are 15–20 hp. If they have a piston compressor or a refrigerating compressor, then they need filters and desiccant units as well. RTI, SATA, DeVilbiss, and Tsunami all make units that dry the air.
What are you recommending for air acceleration?
“We also sell the JUNair QAD units from Europe. [This system consists of four pods, one mounted at each corner of the spray booth. Each pod has eight adjustable nozzles which direct air at the vehicle. The air to the nozzles is filtered down to 10 µ and is produced by two high-performance electric fan units. The air from the nozzles disrupts the laminar flow in the spray booth giving controlled by air movement over the panel. The optimum air temperature together with the disruptive airflow, accelerates water evaporation which speeds up the flash off process and reduces drying times.]
They are the number one seller in Europe. They’ve been around for 10 years and they’re a proven product. The the JUNair’s have automatic doors (most of them) which open during flash off, but close when you’re painting. So when you’re done flashing the doors close and you get no overspray on the nozzles. This matters because if you do get overspray on those nozzles, you’re risking getting dust and dried overspray on the vehicle next time you flash. Even the best downdraft booths, that are not brand-new, have overspray on their walls. And of course if you don't protect your nozzles, they’re going to have overspray on them as well.
What are some shops doing wrong?
People are buying quite a few hand units which is good for up to about three cars a day, but if you’re doing more than three or four cars a day, and you’re relying on hand blowers alone, you’re not going to get the production you need. They take more air than many shops are equipped for. If you’re doing more than a side of a car, you need at least two hand blowers. These blowers take about 12.5 CFM or so. So a piston compressor gives you 3 CFM per hp, and 4 CFM if it’s a rotary (screw) compressor. So to get 25 CFM they technically need a 10 hp compressor to get that much air out of it—dedicated to the blowers only. Very few smaller shops have that much capacity so when they pay for the compressor upgrade, they may as well buy an electric accelerator unit. They’re using more and they really have to look at their air supply. They often have air line problems to begin with. They are just not big enough.
Most of the shops in the old days ran 3/4" to 1" air lines, whereas today we don’t build shops with less than 1-1/2" air pipe because you need that volume. So you have people looking for air and directing the air movement. The fans work, except like everything else in the booth, when you’re painting they do get overspray on them and if they’re not cleaned constantly, as they spin they get out of balance. If they’re mounted to the ceiling they shake the ceiling filter and all the dirt sitting on top of the filter is all over the car. Dirt is an especially bad thing with waterborne.
Other units suck the air from inside the booth around the car and they’re the second best, in my opinion, because they do move the air in the right direction except the blowers will get overspray on them, and they can blow the overspray back on a car.
So we like the technology that closes the doors automatically. So if you take the air from inside the booth rather than the plenum, a little slower. I’m not endorsing one technology over the other as far as how they work. They both work, it’s just that some will work better than others depending on your local setup. JUNair doesn’t put automatic doors on to jack the price up, they put them on because it works. Don’t be ‘nickel wise’ and ‘dollar foolish’ by trying to do it all with handhelds.
What’s the biggest mistake you’ve seen a shop make recently?
I was at a place the other day which had just installed a top of the line Palatek compressor, and what were they installing for air piping? 3/4" PVC pipe! Number one, PVC pipe is against the law in a commercial building because of toxic fumes that they give off and they’re fire hazards. Plus it’s not rated to take the pounding, if somebody hits a PVC pipe with 130 pounds of pressure. The shop was 15,000 ft² and it should’ve been a minimum of 1-1/2". Some shops need 2" trunk lines. I recommend copper aluminum and then galvanized in that order. Copper and aluminum are basically equal as far as clean and easy galvanized would be my last choice because it’s a threaded pipe the threads are subject to corrosion, so I recommend aluminum or copper. Actually copper costs more than aluminum now. You have to be sure to run your drop lines from the top of the trunk line so any water in the line won’t run down your drops.
So what's your experience with costs for waterborne?
I honestly don't think you have to have more costs for paint and materials. I hear different things from different painters. I'm far from an expert on paint. I sell equipment, but I listen to painters. I have painters tell me that there's no real performance difference between the waterborne and solvent. One guy I know puts three thin coats on the car. Another painter tells me he puts one and a half heavier coats on. The material does cost more but from what I see production-wise and color-matching-wise it's a faster production. For equipment, you’re going to spend $13,000--$19,000 depending on what you buy.
So, are shops doing enough to check and change their filters?
I don't know if you realize it but in a downdraft booth when you're recirculating the air during bake, the air actually comes from the pit of the booth which has overspray in it through the filters. The air is sucked through the filters and it gets into the pit and then it's sucked from there up over the top of the filter and lands on the filter. After a while that filter gets dirty and when you start shaking the filter the dirt actually comes back through the filter. Where is it going to go except onto the vehicle. It’s shaking down from the top of the filter down through the filter onto the car eventually.
When you take down the roof filter on a spray booth you'll find more junk on top of that filter than you can believe. It's sucked up through the bottom of the pit. I’ve seen everything from sandpaper to a quarter of an inch of dirt depending how often and how often the owner changes the filters in the booth. Most people don't change it that often. In a year or two years it's all gray and dingy. It doesn't become gray from age, it becomes gray from dirt. I recommend that you change filters every 6 months, if you’re doing 5-7 cars a day, more often if you’re doing more cars.
What do you recommend for filters?
A floor filter is a fiberglass product and depending on the quality it regulates how much dirt gets through the pit and through the motor of the spray booth. There are two or three different manufacturers out there. They'll make each other's filter size. Some are a better than others. Filters are measured in microns, so 6 µ filter will filter anything larger than that. Villedon makes a good filter. Finishmaster sells a couple of different filter brands. You have to see what the best filter based on what the booth manufacturer recommends. Obviously too dense a filter doesn't help the air flow, but a cheaper filter that lets more air through also lets more dirt through.
What are cross draft booth owners doing?
A cross draft is a different animal because during bake it doesn't work quite the same. I don't like cross draft booths because they move the air in a linear fashion from the front to the back of the booth so any dirt that the booth takes in goes past the car horizontally. A downdraft booth only has 9 feet of air to get past the car vertically whereas a cross draft has 24-odd feet of air horizontally. There are quite a few cross draft, or positive flow booths that work like cross drafts, out there.
What can you do for them?
They still have the same problems. You very seldom add heat to a cross draft. You can add heat to a reverse flow booth which has solid doors and air sucks into the back of the booth. You can put a chamber back there and enclose it and blow air in through it. When you do that you can use the JUNair or the GFS units. You still need the air movement around it. There’s a product called XLR8, by a company called Total Systems Group, that stands in the corner and directs the air by pulsation. It doesn't move as fast as the JUNair but it moves air all around the car and disturbs the air motion in the booth. If I can draw the air from the plenum I like the JUNair system. If I can't draw from the Plenum I prefer the XLR8.
Then you have your corner units. Four fans in the corner will dry a car but you don't want the air hitting the surface of the car directly, so much as going down the side and create movement in the booth around the car, like a convection oven. Think about a regular oven versus a convection oven. When you cook in a regular oven and it only gets heat without air. Now we’re talking about convection ovens that circulate air as well. Same thing if you’re trying to dry your clothes. That's why clothes dryers that tumble and heat, work better than drying clothes on the line, especially when it’s humid outside.