Elastomeric Duct Liner

What is the base metal, and why does the duct need lining?

Most elastomeric coatings are not suitable for spraying. They (cob webbing??) deposit unevenly and you will see a lot of overspray. I suggest you use ducts that are made with plastics such as PVC, TPR or PP. Or chose a metallic duct that will not rust (aluminum?)and generate dust with filters installed!! Again I ask same question!! Why do you need an elastomeric coated duct?

Thanks for your response.

- we are a general contractor, and

- we do a considerable amount of work for Property Management companies, and

- this includes works to high rise concrete towers, and

- more often than not, the residences have a 'stacker' washer and dryer, set in the middle of the residences floor plan, +/- 35' - 40' inboard from the exterior wall, and

- the dryer then has to exhaust the moisture laden hot air further than the fan in the dryer was designed to, and

- a common addition to the dryer exhaust is a 'booster fan' , and

- the exhaust duct is a rectangular gi. sheet metal (26 ga.?), and

- the duct is cast into the structural concrete slab, non-accessible, other than access from either end, and

- the exhaust propulsion typically dies somewhere in the exhaust duct (dependant on elbows etc.), condensates, settles in the metal duct, over time rusts through, then starts dripping from the ceiling into the residence, and

- my thinking is that we will dry out the duct (wet-vac out any water then dry with forced air) then push through a spray line, spray and elastomeric into the duct, OK if it all settles to the flat bottom as that's where the duct has perforated from rust, and

- an elastomeric came to mind as the liner as we use a polyurethane elastomeric product on balcony decks as a waterproofing, I'm open to any and all suggestions on how we might line this duct, and

- the ducts have baffles in them so they are not crushed by the concrete or concrete placers stepping on them......cheers

OK graget: better information.

Something that may be a little easier to work with and perform well is bituminous coating in lieu of elastomer. The stuff used to undercoat cars is a pretty good example. Can be purchased in rattle cans, or bulk for spray equipment. This stuff is pretty obnoxious smelling until cured, so that must be considered as well.

As lynlynch says, the real tricky part will be coating around the corners, hidden spots... I can certainly see the project you are up against.

Best of luck. Hopefully someone has a good suggestion for you.

I have been in the HVAC business for 30 years and lint control is one of the most difficult things we have to deal with. Dryer lint is very flammable, and it is becoming a real fire hazard in old high rise apartment buildings. You need to keep the duct surface as smooth as possible because any obstructions will be a place where the lint will accumulate. The reason for the booster fan is because you need to keep the velocity up in order to keep the lint airborne. The fewer elbows the better.

A lot of old high rises used to have a central shaft and what happens is that all the lint ends up at the bottom of the shaft and most supers don't clean it out so you will end up with years and years of lint at the bottom of that shaft.

I would not use any kind of a spray because that will leave a rough surface which will just accumulate lint. I would hire a qualified HVAC contractor to fix your problem. And you should also check with your local codes they may have some new regulations in place that you will need to follow.

Good luck

www.paintcenter.org has information on electrostatic spray coating. This is the only way I can see that you have a chance of coating surfaces that you can't see.

• Paint & Coatings Resource Center.
• PPG Architectural Finishes. Basic information at Paint School, MSDS Search, and industrial paint specification guide.

I don't know if you really need an elastomeric coating. I guess it depends on thermal expansion of the duct?

Painters for the East Bay Regional Park District used our coating to seal and insulate the metal heater duct under a mobile home in one of their parks way out in the boonies. That coating resulted in an 84% reduction in heater runtime and hotter air temperature coming into the mobile home much sooner then before with the standard fiberglass insulation.

If you go to our website at http://www.ct-texas.com and scroll down a bit you will see a statement you can click on that will take you to the file. OR, at the top of the page you can click on where it says 'Does it retain heat' and that will take you to another page where we have that statement and several others where we retained heat with a coat of paint.

Make sure your knickers are bolted on good and tight because what you are going to read there is against the laws of physics, so all the lab rats tell me anyway!

Something as thin as a credit card thick coat of paint cannot be able to stop heat like ours does. Oh well, guess we will just keep going against the grain and proving them wrong.

Cerama-Tech is an elastomeric.

Hal Skinner

Cement Mortar lining systems is a cement lining that is sprayed on typically in 4mm thickness to the ID of the pipe or tube, the head spins as cement is sprayed to the ID of the pipe then a cone follows to apply pressure and smooth the cement to the pipe.

another way to do this is with a 2 part epoxy, spraying the ID of the pipe, care needs to be taken on the total LF of pipe to be coated and the pot life of the epoxy.

If you need information on these processes please feel free to email me.

Mark

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First clean the buildings common dryer duct of lint & debris to ensure/restore it's designed airflow characteristics.

Now,to compensate for modern appliances with greater designed airflow,install a helper fan @ the disharge of the common duct(s) to provide a slightly negative pressure, or to at least prevent a high duct static psi from developing.An HVAC contractor should be able to get things sized correctly for you.

Once you restore/achieve the required CFM the dripping condensate is history.

There will be no successful shortcut to this problem.You need airflow not water containment.

Skies.

Jay.

Try this link http://www.basf-cc.com.au/en/products/SystemsforMining/MembraneTechnology/ThinSprayonLiners/Pages/default.aspx

There is company in Lawrence makes spreyable acrylic base solution fot this purpose. Company name is Custom Nano Adhesive with Tel. phone Number 978-685-8300. You can ask for Jimmy or Steve and let them know I recommended you for this

I would think that the polyurethane waterproofing you are already using would work fine for this. I would suggest picking one of the more accessible ducts (in case you need to try to rip it out if the experiment does not work.) and trying it and see how it works for a month or two, and then gradually try it on the other ducts. Either way, those ducts will have to be as spotless as possible before you attempt such a repair.

The phrase "breathable air" implies that the product should not outgas any noxious fumes, this is probably not an issue. HOWEVER, you need to be aware of the fact that some plastics (PVC among them) can react quite badly to the combustion products from natural gas. There is an issue with PVC pipe used to vent high efficiency furnaces up north ( we don't use them down here in the south, they don't run enough to justify the extra cost.) in which the combustion products lead to cracking of the plastic and CO leaking out and killing people. If these are gas fired dryers and not electric dryers, then this is an issue you need to be aware of. If the ducts are leaking, you need to seal them up or shut off the dryers, one or the other if CO is involved.

You may need to pull new ducting through the existing duct, perhaps two or more round flexible ducts. It will be a bit of a restriction however.