Ask the Expert Question-and-Answer Archive

by Ron Joseph

July, 2003

Paint Emissions From an Aircraft Spray Painting Operatio

Q. Our neighbouring aircraft repair facility regularly performs major aircraft spray painting without having a proper paint dust extractor system. They use 6 locally made extractors (a wooden box). Each box houses two 1 hp electrical motor with a fan attached. The dust filter measures just 1 sq meter. There is no filter conditon monitor (such as a vacuum gauge). Aircraft they normally spray are Fokker 28 & Fokker 100. They positioned these 6 tiny boxes with exhaust inside the hanger to capture the paint dusts.

We can smell the paint odor whenever they paint as paint dusts are escaping to outside hanger and migrating into the local area. Our cars are all contaminated whenever they spray with tiny paint dots. They denied catagorically that their paint dusts are escaping and claim that their paint extractors are efficient.

We need to know:

a) How to determine that their tiny extractor boxes are not efficient and not adequate for the extraction of paint dust of that volume.

b) They claimed only 60 litres of paint (100% PU) is being used. I strongly believe 60 litres is the premixed quantity (without thinner and hardener). The actually volume could be as much as 240 litres (with thinner added). How do I determine volume (rule of thumb) of paint used for passeenger aircraft?

c) It is my understanidng that when painting condition is outisde the temperature and humidity range as recommended by paint manufacturer, paint after spraying on surfaces will not dry and harden within manufacturer recommended duration?

d) Do you conduct a course to give participants adequate knowledge, legal and professional reference texts and articles in assessing that a paint facility is suitably equipped to carry out spray painting without causing nuisance to others and to the enviorment?

A. Thank you for your very detailed email. This is too complex a problem for me to give you all the answers, but I will at least give you something to work on.

The issue is not how many boxes they have, or their respective sizes. Instead, from a fire and safety aspect they should be removing all of the solvents and the paint particulates (dust) quickly and efficiently. For a small spray booth we usually work on an air velocity of 30.5 m/min, but for a large paint hangar the velocity can be as low as 20 m/min. The selected value depends on the concentration of flammable vapors in the spray booth and the LFL (Lower Flammable Limit.). These requirements are intended for the health and safety of the painting operation and its employees, not for its neighbors. However, you should have another concern. There have been several reported fires and explosions where because of inadequate exhausting of vapors the paint facility AND its neighboring factories have burned down! You should be concerned that this does not happen to your factory.

The filters do not capture the solvent vapors and hence it is understandable that you can smell the odors. The only way to avoid that if for the exhaust fans to be large enough to push the solvent vapors high into the outside air. Normally, the paint stacks are positioned on the roof of the building and are approximately 10 m above ground level.

The filters that extract the paint particulates (dusts) whould be at least 99% efficient. This type of efficiency is achieved by incorporating two or more stages into the filter banks. In the US we have several filter manufacturers that sell high efficiency filter systems for such purposes. Many Air Force bases have three stage filters, with decreasing mesh sizes to insure that they get this high efficiency.

You should not be experiencing paint spots on cars in your parking lots. I am working on another legal case where my client, an insurance company has already paid over $1 million to repaint cars for similar reasons. This type of problem is not acceptable and you should be able to take legal action against your neighbor.

For a) above: The company can conduct stack tests in which they measure how much paint solid is used and how much leaves through the filters. Unfortuantely, you need to be inside their factory premises to perform some of these tests. You need to have access to both the inside and outside of the paint spray booth. In a case like this, your neighbor will probably not want to see you even near his premises. Therefore, you will need to take samples of the paint dusts and compare them with the paint that is on the aircraft.

b): I can try to get this information for you, but on a consulting fee basis. I do have contacts in the aircraft industry and can speak to the people who sell paint to Boeing, Cesna, Bechcraft and other commercial aircraft. In addition I do much of my work with the Air Force. This would take a few hours of work.

c): This should not be a factor in your claim against your neighbor. If the paint doesn't dry or harden properly, that will affect the quality of their finish, but should not affect the nuisance emissions impacting you and your property.

d): I give such course all the time, but they are always to my clients. In other words, my clients retain my services for me to come to their facilities to give the course to their painters and engineers. In fact, I'm traveling to a client on Sunday and will spend most of next week doing just that. I do not often give courses to which others are invited.