Air duct covering

[drmile]

these ducts on the photo are normal galvanized sheet metal ducts. What kind of a cover is this? Is it prefabricated or made on sight? 8646 I saw it in the hole building wherever ducts are visible.

[Emmett]

hard to tell from the picture, how old is the duct work? It was not uncommon to insulate exposed duct with asbestos back in the 60's and then incapsulate it with a type of sealant. It also could be fiberglass like one would use on chilled water pipes today.

[AlexG]

Is it fire proof insulation?

[Scramjetman]

Hard to tell from the pic but it looks a bit like spayed foam insulation. Some of the duct fitting manufacturers also use it on Branch take-off fittings. It's similar to the sprayed self expanding foam used in sealing penetrations against vermin access.

[Magoo]

Spray on eurothane [spell check]foam hopefully with a fire retardent like PIR product. Sprayed on site after assembly of ducting. two pot mix at spray gun blown with compressed air. Makes a mess but quick and effective.

[Scramjetman]

Good one Magoo. That's the stuff. Polyurethane spray foam insulation.

Here's some info on the benefits of it: http://www.sprayfoam.com/cnt/docs/9/DeWitt_spray_foam.pdf

[Magoo]

Hi Scamjetman.
I have used spray foam on dumb things like above ground spa and smallish swimming pools with heat pump heating, Vee shaped ice storage augar bins etc., like I said messy but effective, they can double layer as well after a period of time, they skin over and basically have a vapour barrier, but I generally spray again with sealing paint mixture to be doubly sure.
I came across a large chiller complex at a port facility, the interior of the bog standard wharf side shed was spray foamed internally to a average 100 mm, worked a treat, didn't look too flash though

[cool_tech]

it might be vermiculite (not sure of spelling) fire proofing and old version of it used asbestos. sprayed on site.

[Scramjetman]

Hi Magoo,

LOL. I'll bet it didn't look to flash! Imagine trying to dismantle and sell it afterward. At least with a coldroom, it can be dismantled and moved.

I've seen some of the local flexible duct suppliers selling duct fittings like branch take-offs and the like with this stuff sprayed on them. Seems to work ok. We live in the tropics in North Queensland and they don't seem to sweat in the high humidity and its only about 15mm thick sprayed on so it must have a pretty good R value.