Combustion Chamber Insulation

At todays inspection the insulation on the combustion chamber of an old Repco appeared to be fiberglass. The buyer seemed to think it was asbestos. I offered that I didn’t think so but the only sure way to determine that, would be to send a sample to a lab. I have never seen asbestos that looked like fiberglass - has anyone?

Great information


A photo or more info would have been good.


If it looks like cardboard it is most likely asbestos. Some older furnaces used this on the interior cabinet walls of the heat exchanger compartment.

Hi Bill, neither have I, I would bet you were looking at fiberglass



Most likely fiberglass, but good answer if you are not sure. Do you have a picture?

Yeah- it looked like fiberglass - didn’t have the “cardboard” or corrugated look of typical asbestos. The buyer was pretty adamant so I thought I’d check with my “esteemed colleagues” :smiley: Thanks guys.

I don’t know how far back this material was available ( I looked at a year a so ago) but it looked like asbestos and it was not.

The material was a white blanket you can buy from a industrial supply that handles very high temps. I believe it was part “woven glass” like . You can use an open flame and it will not burn.

It was installed in a commercial level FAU . The side of the FAU H/E had this near a side panel to act as a heat shield.

I will try and find it on line and post .

Fiberglass Cloth withstands temperatures to 1,000°F.

    **December 2, 2004** - Manufactured from texturized fiberglass yarn, heat-resistant PARGLASS cloth contains no compound, cement, or wire and will not burn or smolder. It retains 25% of tensile strength, even when service conditions reach 1,000°F, and will not swell, shrink, deteriorate, or change chemically. Available in weights from 8.5–40 oz/yd², product can be aluminized on one side for thermal reflection or have brass or stainless steel wire inserts for increased tensile strength.

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Search the industrial web for: “CLOTH, FIBERGLASS, HEAT SHRINK RESISTANT”](

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Cloth: High Temperature
Cloth: Fiberglass


Archive Press Release
(Products mentioned in this Archive Press Release may or may not be available from the manufacturer.)

Release date: November 25, 2004

Heat-Resistant Fiberglass Cloth Product Line Available from Pars Manufacturing

A line of heat-resistant, fiberglass cloth products, designed for use in foundry, metalworking, heat treating and other high-temperature industrial applications, is available from Pars Manufacturing Company, Ambler, PA.

PARGLASS Fiberglass Cloth is a plain, tightly woven cloth manufactured from texturized fiberglass yarn; it contains no compound, cement or wire. Engineered to withstand temperatures up to 1000 degrees F, PARGLASS fiberglass cloth meets United States Coast Guard requirements for incombustible materials and will not burn or smolder.

Recommended uses include welding curtains, fire blankets, insulation blankets, industrial and marine lagging, asbestos cloth substitute and drape cloth, among others.

In contrast to many high temperature fabrics, PARGLASS cloth is exceptionally strong, retaining 25% of its tensile strength even when service conditions reach temps of 1000 F. Other properties include good thermal conductivity, high dielectric strength and low constants.

Unlike other gasketing or insulating materials, the product will not swell, shrink, deteriorate or change chemically even after long exposure to water.

PARGLASS Cloth is available in a variety of weights (8.5 to 40 ounces per square yard), finishes (heat-treated, waterproofed, weave set, renwet and/or flameproof), coatings (neoprene, vinyl, Teflon., and constructions (aluminized on one side for thermal reflection; with brass or stainless steel wire inserts for increased tensile strength). Company Information:
Name: Pars Mfg. Co.
Address: 101 S. Main St.
City: Ambler
State: PA
ZIP: 19002-4717
Country: USA
Phone: 800-871-5302
FAX: 215-646-1368

How can you all speculate as to what this stuff is? Even if it looks like asbestos we can’t say it’s asbestos. Unless we send it off to a lab and verify, we don’t know!!