Exhaust Paint Stack Cleaning – Dry Ice to the Rescue

Here at Indigo we’ve become adept at cleaning paint exhaust stacks.  This experience has come at no small cost, mostly in time, as we learned very early to carefully plan where the dried paint we were removing was going to end up.  Once airborne, if you don’t keep it contained your cleanup area expands by a factor of 10X.

Let’s start at the beginning.  Paint exhaust stacks are an ideal candidate for being cleaned on a regular basis using dry ice blasting.  Dry ice blasting generates no dust from media, it does not generate any moisture to cause headaches with clumping liquid old paint, and it is fast in the vast majority of applications.  An added benefit is dry ice blasting can also clean the exhaust fans without any worries of damage to the motor or electrical disconnection requirements.

Here’s the basic process.  In an ideal setup, we are cleaning multiple stacks in the same booth area.  This is ideal because we can lock out one fan on the first exhaust stack, and then turn on another fan in an adjacent stack, which will control the dust while we clean the first stack, then we just use the first stack and fan to clean all the others within the booth.  I should mention that we seal off the booth with heavy plastic and duct tape to contain everything within that booth.

Unless it’s not safe to be on the room, we typically route the cleaning equipment up through one of the stacks, we have ample blast hose to allow the machine to sit in the booth and the hose and nozzle to be on the roof through the stack.  We then begin cleaning any cowling or “hat” on the stack, or the fan if it happens to be a top mount fan, then start blasting downward with angled fan nozzles to clean the surface.  We continue down until we reach a fan if it’s mounted internally, then we move down to the booth and clean the underside of the fan and on down to the booth.  As mentioned above, we clean the next stack and so on until all are cleaned. 

Once all stacks are cleaned with clean off our equipment and sweep up all the dust that landed on the booth floor and make good our escape.

If there’s only one stack in a booth you have extra dust to content with, but we usually can rig a portable fan assembly to assist in clearing the dust while we work, otherwise it’s a full mask blizzard in the booth until we finish.

Some tips that lower costs and improve efficacy.

  1. Cleaned exhaust stacks and fans greatly increases the efficiency of the exhaust system, which contributes to better quality by preventing coating fallout from landing on parts in your process. 
  2. Cleaning the stacks regularly pays dividends in the increased efficiency, and by happy coincidence also lowers the cost of routine cleaning since a stack that is regularly cleaned goes much quicker than one that has a year or 20 of buildup.
  3. Frequency of cleanup depends on how often your booths are used.  If you are spraying three shifts a day, every day, you probably should clean them at least once or twice a year.  The quality of the fan, the filters in the booth and the skill of the applicator also affect this timetable, so there are a variety of factors at work.
  4. If you only use your booth periodically, and have a good filter system, you might not need to clean it more than once every two or three years.
  5. If you ask me, you should clean your paint stacks many times a year, and you should let Indigo do the work!  But a good contractor will give you good advice about how many cleanings you should do, we find that we generate trust and goodwill by not trying to push more cleanings than are necessary for optimal results.
  6. Not every painting or coating product reacts the same to both booth buildup and cleaning speed.  High temp paint and epoxies are difficult, some solvent based paints dry so quick that it’s more a dusting process than a blasting process,
  7. Bolts and protrusions into your booth stack attract the biggest paint buildup, so good stacks have the bare minimum of obstructions.  Avoid have a bolt nut inside the booth, try and keep the bolt head inside the booth, and make it a carriage bolt type that’s low profile and rounded.  Same goes for assembly of stack sections, make sure they are smoothly connected.

There you have it.  Paint stack buildup solved in a few simple steps, and some tricks to avoid bigger problems down the line.  Until next time, keep your surfaces in good order!

Fan before and after dry ice blasting