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Kitchen Exhaust Cleaning; Boiling-Hot Pressure Washing

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T O S

(Theory of Survival)

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For a more thorough recent article on this topic click here.

(Original Article submitted to "Chemical Innovation" Magazine)

(not what they did to it)


Intumescents are defined as follows in the Glossary:

Intumescent: Substances which swell as a result of heat exposure thus increasing in volume and decreasing in density. Intumescents are typically endothermic to varying degrees, as they can contain chemically bound water. Intumescents are used in firestopping, fireproofing and gasketing applications. Some intumescents are susceptible to environmental influences such as humidity, which can reduce or negate their ability to function. DIBt approvals quantify the ability of intumescents to stand the test of time against various environmental exposures. DIBt approved firestops and fireproofing materials are available in Canada and the US. 3M Canada is one such vendor.

You may look up the other terms written in italics in the Glossary as well.

Although somewhat contrary to the true definition, intumescents are categorised as passive fire protection measures. After all, there is motion, during the intumescing process and lots goes on chemically as well.

One may further distinguish between high expansion and low expansion intumescents.

Here is an example of a high volume intumescent:

High Expansion Volume Intumescent

This material forms a lightweight char, or carbon foam. It is also highly endothermic, due to the about 1/3 content of chemically bound water, by mass concentration. The resulting carbon foam exerts little pressure. It would be unsuitable for plastic pipe penetrations, yet desirable for providing cooling vapours and a layer of thermal insulation, due to the nature of the char produced.

Here is a similar intumescent, as used in structural, spray-applied fireproofing:

Unitherm thin-film intumescent being exposed to fire.     fully engaged Unitherm thin-film intumescent

Here are some lower volume, yet high strength intumescents. These contain less water than the intumescents shown above. Sodium silicate typically contributes no more than about 10% water by mass concentration. The material on the left is ageing stable on its own, whereas the one on the right requires external waterproofing by means of epoxy.

FS195 intumescing       Palusol based Plastic Pipe Firestop Device

Uses for Intumescents

Fire Door Gaskets

intumescent fire door gasket

Firestops

Intumescent firestop putty being installed

Spray Applied Fireproofing

structural steel (indoor, usually thin film, unless very high fire-resistance durations are required)

LPG Vessels (thick, epoxy based, exterior grade systems qualified to hydrocarbon fire testing)

Pipe Bridges (thick, epoxy based, exterior grade systems qualified to hydrocarbon fire testing)

Vessel Skirts (thick, epoxy based, exterior grade systems qualified to hydrocarbon fire testing)

Cable Coating (usually indoor, usually thin-film materials applied to reduce surface burning characteristics of combustible cable jacketing)

Timber Coating: (indoor or outdoor, usually thin-film, to reduce surface burning characteristics)

Problems with Intumescents

Some intumescents can be used only in very limited applications because their intumescing properties can disappear within days of installation. The culprits here are the various environmental influences, such as humidity (even indoor, normal humidity!), UV, operational heat etc. Vulnerable intumescents must be protected by epoxy or rubber coatings of some sort, to ensure operability. Responsible vendors of vulnerable intumescents clearly state that their products require protection and that if the protective layer is breached, one must immediately patch and make good. But not all manufacturers are that responsible or even aware. Some appear to be blissfully unaware that their intumescents should really be confined to the laboratory. For instance, using commercially available sodium silicates (a chemical commodity widely available through chemical distribution houses), any moderately skilled entrepreneur could conceivably concoct a product, which will intumesce. But will it do so a week later, regardless of whether it be installed in the Okanagan desert of BC or in Southern Ontario or the Northwest Territories? There have been a number of product recalls to date for faulty firestops - including in Canada and the US. You might want to think about that, as an architect. It's one thing when a car manufacturer recalls a type of car. You drive it to the dealer. The dealer fixes what is wrong, free of charge and you're on your way. But it's not quite that simple, when it comes to passive fire protection items, which are concealed behind the finishes of occupied buildings. Thus, we now know beyond the shadow of a doubt, that there are quite a few buildings out there, which have no fire separations, because you may rest assured, that not too many folks dug holes into their drywall and masonry and so forth to replace faulty firestops.

Solutions to Intumescent Troubles

In North America, the only decent standard that addresses serious environmental exposures and the longevity of intumescents is UL1709. Unfortunately, after the environmental abuse, UL1709 only covers testing of structural steel columns against the hydrocarbon time/temperature curve. UL1709 scares the pants off most intumescent manufacturers, and for good reasons. It's one tough set of tests, as it should be, considering the harsh applications being qualified for (exterior hydrocarbon fire protection). This does nothing for interior products because no one has tested common interior passive fire protection products to UL1709. The best and most scientifically sound method for bench scale testing is the DIBt method. DIBt is an agency of the Federal Republic of Germany. Its function is that of an accreditor of laboratories as well as approving agency of products and systems. DIBt approved firestopping and fireproofing products are available in North America. One such example is 3M, for its intumescent firestops. Another example is Nullifire, for its thin-film intumescent spray fireproofing product. UL and ULC committees are considering a watered down version of the DIBt method at present. Neither the US nor the Canadian manufacturers (who make up the bulk of task group membership) appear to be excessively enthusiastic about entering the environmental exposure criteria (apart from those who already have this aspect covered), which is actually the real issue at hand. It is the environmental exposures that cause some intumescents to fail. This costs money and it could be embarrassing for some of them and so it's tedious to get this passed at the standards writing table. Without the environmental exposures, you simply have an ageing test, which is based on heat exposure. No humidity, no UV, no temperature cycling, etc. The result will nicely sidestep the real issues (pencil-whipping), while creating more paper to back up the lacking status quo on this continent. The solution is quite simple though. As the architect, simply demand to see current copies of the DIBt approval of any intumescents you may use. Otherwise, don't permit the product. It may very well be good stuff, but how do you know? Marketing literature? Sales Rep's promise? This is one of the reasons I stick to 3M products. No BS - current DIBt approvals on 3M intumescents are no problem.

Some Swamp Land For You

There is a common myth, perpetuated through creative sales:

Intumescents can't spread inside of cable bundles

Some folks will tell you that because their intumescents do what they do, it is not necessary to open up cable bundles and seal between cables. They would have you believe that the intumescent will swell in such a manner as to spread inside of cable bundles to make a smoketight seal. This is, of course, a physical impossibility. Cold smoke sealing (which saves lives and property, particularly electronic equipment) is based on firestop workmanship. Regardless of what the firestop is made of, it is imperative to seal inside the cable bundles. And with the whopping ten percent water that sodium silicate may contribute, the intumescent is not doing an excessive amount of cooling here either. The best cable penetration seal is firestop mortar. Mortar becomes impractical in very small openings though.

BACK to Products

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Intumescent Products

Endothermic Products

DIBt Intumescent Test Procedure

DIBt Reactive Spray Fireproofing Test Procedure

Main Site

Firestop Site

Code Evaluations AVAILABLE!

Glossary of Fire Protection Terms

3M Fire Barriers

Vectorising Drawings and Maps; Paper to CAD

Circuit Integrity Fireproofing

Bounding

Code Req's for Firestops

Essay on Performance Based Codes

Master Spec. Section 07840 Firestopping

Related Sections to 07840

Penetration Seal Drawings

Building Joint Drawings 1

Building Joint Drawings 2

Building Joint Drawings 3

History of Firestops in North America

Warnock Hersey Experience

Firestop Trade Jurisdiction

Achim Hering Bio

Man Made Mineral Fibres

Fire Protection Industry Links

Firestop Products and Equipment

Firestop Mortar

Firestop Silicone Foam

Intumescent Products

Endothermic Products

Insulation Products

Caulking & Paint Firestops

Firestop Pillows

Firestop Devices

Firestop Slide Show 1 of 10 Basics

Firestop Slide Show 2 of 10 Code

Firestop Slide Show 3 of 10 No Seal

Firestop Slide Show 4 of 10 Deemed-to-comply

Firestop Slide Show 5 of 10 Misinstalled

Firestop Slide Show 6 of 10 Re-entered

Firestop Slide Show 7 of 10 Faulty Spec.

Firestop Slide Show 8 of 10 Proper Firestops

Firestop Slide Show 9 of 10 Test

Firestop Slide Show 10 of 10 Smoke and Trays

Sample Firestop Listing

Kitchen Exhaust Cleaning; Boiling-Hot Pressure Washing

ULC           UL

T O S

(Theory of Survival)

DIBt

TU Braunschweig iBMB

CONTACT

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