Filters and Air Flow in Paint Booths: Why You Can’t Have One Without the Other

Written by: Jeremy Winters

We all know it is inevitable that every round of hours, it comes time to change the booth filters. For some it’s a headache, for others it is just part of the job. Some bigger shops hire companies that service the booths doing filters, some say “it’s not my job.” Whatever your take on it, it is one of those tasks that comes with the territory, however there is more to a simple filter change than taking the time to do it. Let’s dive into some of the things that may not even be crossing your mind when it comes to the simplest of booth maintenance.

One of the nice things about Accudraft booths is having 2 sets of exhaust filters: the floors and the rear sets. These should ALWAYS be changed at the same time for a variety of reasons. Let’s say that only the floors are changed and the rear sets are not. This is going to offset the amount of loading on the filter packing between the two. The secondary set is going to clog up faster and you will find that even with the floor filters being fresh, now you are probably fighting pressure issues in your booth. Or, let’s say you want to change the secondary sets but not the main floor filters. The same result will happen, the floor filters are going to become the choke point of the booth, not allowing it to breathe and causing numerous issues.

Let’s discuss some basic information that is uniform across ANY booth that’s out there. A paint booth is, in theory, a giant air pump. Air is forced in; air is pulled out. It is literally just that simple. Just like with any air pump, whatever air comes in has to go out somewhere. If the booth is choked from dirty filters, then air is going to find the easiest way to escape. This includes bouncing off the walls, stirring up dirt and dust as it searches for the weak point in the booth. Often times, this is when we see the booth doors getting blown open from too much pressure in the booth. Air HAS to be able to flow freely through all of the filters to properly evacuate overspray vapors. What if you have fresh floor filters and rear filters but are still having issues? Ceiling filters are often the most overlooked filters in the system due to the labor required to change them. They can cause issues just like the floor filters because the air is trying to get through them. Instead of flowing, the air can be building pressure in the upper section above the booth, which causes dirt and debris to become dislodged. The bad part here is that those contaminations will most likely be blown down and will wind up in the hood that you just cleared.

But let’s look at it this way as well. I’ve been in the situation that many of you reading this have been before, where I knew it was time to change filters but couldn’t. The booth pressure was rising each day, you could see the filters were loaded, BUT I had cars to paint. They’re lined up and of course “had to go.” What other issues can arise from improper air flow? Not enough air coming through to carry the solvents away can mean that the overspray isn’t being evacuated, and now that overspray settles down on the surface. Improper airflow can/will result in dieback issues and solvent pop as well. These are just a few of the things that can happen when putting off what should be done. Unfortunately, too many times, a booth malfunction gets blamed on other variables rather than the actual issue at hand, FILTERS!

Another issue I hear about is having to cut filters to fit and that it takes too much time to change the filters. This is one of the simplest things to correct, as most times, I find that shops just order filters “close” to what they need and put it on the technician to handle–all the while, complaining about the time taken to do said job. It’s sad, but truth be told, I’ve been there, seen it, and done it in my career as a production painter. The simple act of ordering the right size filters for your booth may seem like an added up-front cost. But looking at the return in time saved is something that gets overlooked far too often. Let’s say you have two painters and they change their own filters. Are they paid hourly? You’re now paying those two painters X-amount of dollars just to change filters rather than pull a trigger in the booth. What would the savings return on ordering the proper fitting filters be? Just on the time saved in labor? Your guys are paid commission? How much further along could they be on the next job compared to having to sit and cut filters to fit? Again, results in less booth downtime and more production time, increasing your bottom line per RO.

It seems that we never have time to do it right the first time, but we always have time to do it a second time, which technically loses you 3 cycles and not just 1. So not having the time to change filters or neglecting to, will cause many more issues that can cause costly reworks or full buffs, both of which kill your bottom line profit available on the job. For this, it is extremely important to follow a maintenance regimen to keep the spraying environment as consistently uniform as possible. This helps to ensure a consistent end product, which of course, helps bring up the bottom line. Every filter has a certain number of run hours where changing is recommended—keep up with those hours and change accordingly to keep everything running longer without failure.

But are the results of poorly kept filters just impacting the end results of the vehicles being refinished? Negative, it also has detrimental effects to the booth cabin and parts as well. Fans load up and come out of balance, motors get hotter faster causing premature wear, the cabin is getting constantly flexed from the pressure increases, which can cause welds to eventually break just to name a couple of things. All of this is going to wind up hurting the shop in costly repairs to the booth, just because somebody didn’t want to replace a filter.

Here at Accudraft, we stress the importance of keeping the air flowing through the booth as it should. We offer all filters for our booths as well as a multitude of options. Give us a call today and see about your specific application.