Painting Inside Ductwork 6

[IBechir]

Greetings

My project specifications call for painting the visible internal portions of duct outlets in dull black. Unfortunately I have no further details regarding this paint. I am concerned about the impact this paint can have on the health of the occupants because these are ventilation ducts (office fresh air). Is there a certification mark I should be looking for like low-VOC/lead?

The project is an office commercial building and the ducts are made of galvanized sheet to ASTM A 653.

Also I know there is an ASTM guide for treatment of zinc-coated steel surfaces for painting (D 2092) but does anyone know if are there paints that adhere directly to the zinc coat? It will might make application easier.

Much obliged for sharing your professional opinions.

 

[Compositepro]

In terms of health it makes no difference if the paint is in the duct or on the walls.

 

[dbill74]

Contact the specification writer and ask them to clarify the paint requirements. Anything like low-VOC, lead free, etc. should have been included in the specifications.

If a product does not meet specifications or client's requirements it is not acceptable for the project regardless of any advise or opinions we offer in these forums.

 

[berkshire]

On the shop floor , the most commonly used paint was a flat black, lead free paint, LOW VOC is only required in certain areas of the country, so most fast drying paints are usually acceptable from a production point of view, once the paint is dry, it is pretty inert. Again adding to dbill74s post check with the spec writer.
B.E.

You are judged not by what you know, but by what you can do.

 

[EnergyProfessional]

You need to degrease the duct. Ducts will have some grease and the paint will flake off over time.

I'd use low VOC. I only would be concerned with hot air, but i doubt this is the case?

 

[IBechir]

Its a cold air duct. You are right of course, contacting the specifier is a must. Instead of sending a few pieces of duct to the shop for chromate or zinc phosphate surface treatment as in D 2092, will it not be easier just to glue a black fiber mat (that does not laminate) on those visible portions? Then again, for the glue to adhere, surface treatment will still be needed.

Thanks again for all your input

 

[Drazen]

no chance you are allowed to do that in supply air duct.

all paints contain toxic volatiles that gradually evaporate. it's health hazard for ordinary furniture paint, not to mention circumstances where supply air goes directly to your lungs.

your specifier is likely not familiar with hvac engineering.

 

[IBechir]

Drazen, thanks for your comment. Some fungicidal coatings claim to be suitable for use inside ducts because they only release water and are certified to standards like ASTM C 411. I thought there might be a similar paint product. What about water-based paints?

 

[EnergyProfessional]

what's your role in this, are you a painter? Or duct installer?
either way, you should get directions from the designer... so he will be responsible for any VOC. Get it all in writing, because if later the paint peels off, or occupants complain about the smell, or get cancer, they will come after you. This is a bit hyperbole, but you get the general idea.

i assume this is part of the architectural idea and the person who wrote this doesn't have a background in painting, ductwork, or IAQ.

 

[Drazen]

i tried to go over basics, just for understanding, but i'm not chemical or medical specialist. you should find paint which is exactly specified to be used on the inside of supply duct, while i never heard of such one myself.

 

[IBechir]

Thanks. I will discuss this further with the painting specialist when one is assigned to the project; along with product certification for intended purpose and application method. At least I know that my concern was valid.

 

[dvd]

Your sheet metal contractor typically glues (and pins) insulation to the inside of ductwork. Most sheet metal shops will spray the edges of exposed insulation with the adhesive, which happens to be black. See if your sheet metal shop can just spray the interior of the duct with the same black adhesive (be careful not to stack anything on these surfaces). The adhesive is obviously made for spraying onto the galvanized duct surfaces and must be meeting any voc requirements.

 

[EnergyProfessional]

I would be careful using the black adhesive. first, it may meet IAQ requirements if it is covered with liner, which wouldn't be the case here. Second, it may be very sticky and attract a lot of dirt and will look weird. It also may age when exposed to light etc. since it is not made to be exposed.