Wednesday, 02 April 2008 11:47

First Steps in Conversion, Get an Air Audit

Written by Jeremy Hayhurst
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RTI’s Sean Martinez is a guy you want to see early in your process. Working with a jobber, an air audit can very quickly put your finger on sources and solutions for contamination, humidity, and volume. An air audit can be one of the most important diagnostics to save time, trouble, cost and grief later on. We asked Martinez’ manager, Larry Parker, Reading Technologies, Inc. National Sales Manager, Automotive Division to describe RTI’s products and process.

{jcomments on}    Says Parker: “We’re dedicated to producing products that fix the body shop’s problems and with waterborne it’s much more a concern because of its sensitivity to contamination and humidity.  Most of the shops I’ve gone into  have been getting away with it with solvent, but they’ll have problems with waterborne unless they fix their air quality.

What would you say the the biggest demand is for product right now?

The biggest demand product right now is our PERF 25 air systems, which is one booth set up or one painter setup. We also have a PERF 50 which is set up for two sprayers or two booths. Waterborne air usage is sometimes three to four times what they used for solvent-based products. We make a manual replacement desiccant (our eliminator product) but with the additional usage, those products are saturated very quickly and need to be maintained two to three times more regularly than they were prior.

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Sean Martinez does air audits for RTI, a critical step in identifying potential air quality and supply problems. Martinez lives in Salt Lake City but flies to work with California jobbers and shops every week.

There’s a history of shops not maintaining their air and that creates problems. You need consistent clean dry air.  What a PERF 50 or PERF 25 does is take all the oil mist out.  We also keep the the humidity at essentially 0% and the units regenerate so you have new fresh desiccant every time.  Desiccant has got a bad rap because the dessicant sometimes breaks down and causes contamination. Some of the units out there do not have post-filtration so they tend to create some contamination.  All of our PERF units have final filtration which eliminates any desiccant breakdown or any contaminants coming from the desiccant bed.
The pre-filtration is basically for oil vapor droplets and the post-filtration is to stop the desiccant contamination itself. Another thing that’s big now is an active charcoal bed. RTI, since its inception in 1987, has had active charcoal in our first stage elements to remove oil mist from the air lines. Many of the systems out there are now adding those active charcoal beds but as we do air audits we’re finding that those units can deliver contamination from that active charcoal into their paint surfaces. Active charcoal works to absorb oil mist but  it should never be used as a final filter.  
Probably only 1 in 50 shops have no contamination at all coming through their air lines. A compressor, especially a piston compressor, tends to create contamination. Active carbon does not remove humidity. It only removes oil mist so, for productivity reasons, you’ve got to control the humidity in your air lines.


We went into one of the major paint companies and did a demo with both waterborne and solvent.  We found that with solvent on a black basecoat keeping the humidity level very low made a big difference. Most desiccant units have an indicator paper that changes color when the moisture is over 10%.  We tested at 14% humidity, which is really when most of those papers change. Our PERF system yielded 0% percent humidity. We found that the panel with 0% humidity was 10 minutes faster flash time in the solvent-based. With waterborne, without added airflow, we found that it was 15 minutes faster flash time without having to blow extra air over the panel.
We do an average of 36 audits a week, (with 41 reps nationwide) and we find the average percentage of humidity in the body shop is from 30 to 40%.  When you add that to the equation of between 14 and 0% it makes a big difference in production.

I have a high production shop who put in one of our PERF 25 units who told me he gets one more car per booth now.
Many of the shops in California are busy changing paint and systems at the same time. If they spend the money for a PERF 25 unit the paint performs much better. It’s just physics. If you have 0% humidity in your air you’re pulling a lot of the water off the surface in your spraying.  At 70° you can have 73% humidity in the air.  If you start with 0% that’s a lot more water that can be picked off the surface. Whether using handhelds or not, keeping your air at 0% humidy makes everything perform much better. I think you find with waterborne you can’t do things the way you used to do them.  You’re going to need some investment. The number one investment that you have to have is a compressor big enough for adequate air volume and something to clean and dry the air.  
We are basically recommending screw compressors for two reasons. First, the duty cycle on a piston compressor is shorter, and piston compressors create much more heat and oil vapor. They actually will not last as long. The piston compressors give you between 180° to 200° air coming out, whereas  a screw compressor, even without after coolers, comes out about 120° and that itself lowers the humidity content. The lower the temperature, the less moisture the air can hold.

With the PERF air units a refrigerant dryer is not necessary because the unit dries it very well. But a refrigerant unit might be useful for the rest of the shop.
Our recommendation is to replace the desiccant every three years and if they have a refrigerant dryer it would be every five years. We give a written guarantee for three years. Our suggested price is $2199 for a PERF 25 and $2699 for a PERF 50.  You might want to look at a PERF 50 if you’re using four to six air blowers.
With the two filters prior to the desiccant, replacement is once a year on the first stage and every six months on the coalescing filter. For the post-filter it’s every six months. If the shop air audit shows a lot of oil contamination it does need to be replaced more often. I would check them monthly and maybe plan a quarterly replacement in the prefilters.
We do a free air audit anywhere in the United States by one of our trained representatives like Sean Martinez. They provide a three-part form which gives you a written report on your system. Problems we find are pipe scale and rust coming through the line and we also find a lot of desiccant breakdown if they’re using other products.  

RTI can be contacted at 800-521-9200, or Sean Martinez can be contacted via email at See RTI’s ad on PP39.


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