Plastic Heating Pipes in common areas.

[Golden]

Hi Goodsparks - a colleague of mine took some home to carry out the 'test' and there was no mention of plastic coating; if this was the case then the situation would be worse as the water in the pipe wouldn't figure significantly in reducing its combustibility.

Here's a pic of the range pipes for a bit more detail.

[SamFIRT]

if this was the case then the situation would be worse as the water in the pipe wouldn't figure significantly in reducing its combustibility

Yes it would as the heat in the plastic coating would be conducted through the metal into the water and the latent heat capacity effect would still apply. Granted there may be some scorching of the plastic as there is a delay in transferring the heat into the metal, like the sooting on the balloon in the U tube clip I posted.

Fill the pipe with water and apply a blowtorch. I would be very interested in the result.

[Fishy]

If you’re in England & Wales, look at Section 10 of the Approved Document B.

The water filling is irrelevant, for many reasons, not least because a) you can’t guarantee that the pipes will always be filled & b) as soon as they melt the system will drain.

[SamFIRT]

as soon as they melt the system will drain.

They won't melt it there is water in them. So they can't drain. Obviously if they are not filled with water then they will pyrolyse, scorch, char, melt or ignite; depending on what they are made from.

Can't comment on ADB.

[Fishy]

as soon as they melt the system will drain.

They won't melt it there is water in them. So they can't drain. Obviously if they are not filled with water then they will pyrolyse, scorch, char, melt or ignite; depending on what they are made from.

Can't comment on ADB.

I'm not sure that I agree that they wouldn't melt.  The 'paper saucepan' works because the paper is thin so the heat is rapidly absorbed by the water.  The polymer is likely to be a good insulator & so if subjected to direct flame it'll get above its glass transition temperature (80-odd degrees C if it's unplasticised PVC) on its exposed face.  I really can't see a conventional polymer pipe keeping its integrity if directly exposed to a significant fire, no matter whether it's filled with water or not. 

Having said this, I do know that sprinkler systems can utilise polymeric pipework (e.g. CPVC & Polybutylene), but I think that this is normally done either on the basis of the pipework being protected from direct flame impingement, or being protected by the activation of the sprinklers themselves (not really my area of expertise)?

[SamFIRT]

It would be an interesting test.

Perhaps someone should do it.

[Mike Buckley]

Having said this, I do know that sprinkler systems can utilise polymeric pipework (e.g. CPVC & Polybutylene), but I think that this is normally done either on the basis of the pipework being protected from direct flame impingement, or being protected by the activation of the sprinklers themselves (not really my area of expertise)?

Either that or fire melts sprinkler pipe that then bursts dumping water onto fire.

[Golden]

BS1285 recommends that steel or copper are used and that for dry, alternate or pre-action installations, galvanized steel should preferably be used, 9251 recommends that "Plastics and other pipes and fittings should be in accordance with a standard as recognized by the authority having jurisdiction and suitable for residential and domestic sprinkler systems and should be installed in accordance with the supplier’s instructions." but makes on mention apart from giving dimension guides on CPVC.

CPVC is a thermoplastic material that chars and will not support combustion, it is rated as self extinguishing. They are approved for wet systems only which will allow the water flow to carry away the heat once a sprinkler has actuated. There is no mention of static water in this note http://www.ribaproductselector.com/Docs/8/23138/external/COL68349.pdf

I think I'll get the full specification for the pipe and fire this one off to the passive fire protection guys to see what they say.

[Psuedonym]

Plus CPVC is a damn sight cheaper, lighter, easier and quicker to install...