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Participant

Join Date: Feb 2017
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Ignition of E-glass Fibre Cloth

02/15/2017 9:16 AM

Hello,

I have been testing some new E-glass fibre products for use on a thermal insulation jacket to be used on a gas power generation engine.

I have discovered an interesting phenomenon which i am struggling to comprehend, perhaps one of you will know the answer...

According to our supplier, the base fabric E-glass cloth I am testing is rated to 650°C with a polyurethane coating rated to 180°C. The polyurethane is to aid with manufacture and is designed to flash off over 180°C.

Initially I simply heated the material directly with a naked gas flame at ≅ 2000°C. I observe both the coating and cloth degrade but crucially they do NOT ignite.

In the second test I aim to simulate operating conditions. I heat a stainless steel pipe up 600°C (using the same gas torch) and then wrap the cloth tightly around the pipe. This time the cloth instantly ignites and burns for up to a minute.

I am very surprised by this result and would really appreciate if someone could shed some light on the situation.
Thankyou!
Ollie

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Guru

Join Date: Apr 2008
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#1

Re: Ignition of E-glass fibre cloth

02/15/2017 9:27 AM

That is interesting? Does the wrapping somehow prevent the poly coating from flashing off quickly? I know somebody will say to speak with the manufacturer.. Which I'll bet you did.. or will.. Please let us know what they say.

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Guru

Join Date: Oct 2008
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#2

Re: Ignition of E-glass fibre cloth

02/15/2017 10:00 AM

Probably because the open flame is flashing off the PU coating to rapidly.

The hot pipe provides no actual flame front to burn off the coating but heats a larger area to ignition.

I'd definitely ask the supplier how they test the cloth and following those test procedures exactly, or all bets are off.

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#3

Re: Ignition of E-glass fibre cloth

02/15/2017 10:32 AM

Maybe there is more oxygen available when you wrap it around the pipe. Possibly the atmosphere around the flame is mainly combustion products from the flame.

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Participant

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#4

Re: Ignition of E-glass fibre cloth

02/15/2017 11:11 AM

Thankyou for the quick responses guys.

Yes I have spoken to the manufacturer. They tested the material by fixing a metal plate in front of a furnace and allowing it to reach a surface temperature of 630°C before pressing the sample material against it.

They observed as soon as the material was put in position it ignited and after 10 seconds the whole sample was completely burning. So a very similar result.

This would lead me to believe it is to do with the mechanism of heat transfer - for some reason conduction seems to have a more severe result. Does anyone know why?

Thanks again for the help.

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#5
In reply to #4

Re: Ignition of E-glass fibre cloth

02/15/2017 12:14 PM

I would think the pressed poly is more slowly wicking out from it's backside (like a candle). making the burn more controlled and evident.

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Participant

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#7
In reply to #5

Re: Ignition of E-glass fibre cloth

02/16/2017 4:09 AM

I think you may be right. I guess with the high temperature naked flame the PU is being vaporised very quickly so i would not observe any ignition beyond the flame of the blow torch. Thanks!

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#6

Re: Ignition of E-glass Fibre Cloth

02/15/2017 12:22 PM

Are you certain your test material is burning and not some oil anti-corrosion that was on the pipe already?

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#8
In reply to #6

Re: Ignition of E-glass Fibre Cloth

02/16/2017 4:10 AM

Yes, i was careful to ensure no contamination.

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