Source of Aluminium Lined Plastic Water Pipe?

I'm looking to build a loop antenna from a continental design that suggests using a particular type of plastic water pipe. It's made with a thin layer of aluminium between the plastic interior and the plastic exterior.

Not sure what the aluminium is for when the pipe is used for plumbing. It might be for heat insulation or as a barrier to stop muck leaching into the pipe. Seems unlikely to be for electrical safety.

Anyway, whatever the lining is for, this type of cheap bendy pipe is recommended as an easy way of making broadband loop aerials. The diameter doesn't matter much - ideally minimum 15mm but not too big (say 30mm) because fat pipes are harder to bend. The main objection to doing the job with ordinary copper water pipe is cost plus the extra difficulty of bending copper pipe into a perfect metre diameter circle. As it's an antenna, it's best to avoid joints.

I found a single supplier on the internet who confirms his rather pricey pipe has an aluminium shield but it's a trade wholesaler. It's a dead end. However, there are lots of plastic barrier pipes on the market that might be aluminium lined, but their specifications don't confirm it. To save me being arrested in B&Q for attacking pipe ends with a Stanley knife does anyone know of a source in the UK?

Thanks,

Dave

Is it this stuff, Dave ? ... **LINK**

http://www.theunderfloorheatingstore.com/water-underfloor-heating/accessories?cat=44

MichaelG.

Not sure about antenna length effects here but two possible alternatives maybe -

Plastic tubing made around a spiral metal wire. The wire is continuous but going around the tube diameter could triple (pi*d) the length.

Second option is externally braided tubing, a bit like brake hoses etc.

Something similar, but for a different end application is Dekabon tubing - it's usually used for instrumentation tubing (compressed air) polymer outer over Aluminium inner. The name Synflex also seems synonymous - a quick web search reveals several UK stockists. A few sizes available - not sure what the minimum length you can buy is ….

Cosmetic plastic loop protecting a metal wire inside?

Neil

I don't know of a source in the UK, but its used everywhere where I live, and costs only a few pennies per metre. I think the stuff originated in Italy, because all the associated fittings are made in Italy. Not sure how easy or expensive it is to send it to the UK, but if you get really stuck, let me know and I'll see what I can do (before the Brexidiots stop international trading), assuming you don't want tens of metres.

As you describe, it is a thin aluminium tube about 15mm diameter, coated internally and externally with plastic, and is used for hot and cold water. The joints are made using a collet-like compression fitting. It cannot be bent too sharply without kinking - I would say about 30 mm radius is as tight as you can go (thats a guess based on usage). The aluminium tube appears to be a continuous tube, not wound from foil.

It doesn't like overheating - boiling water (as opposed to 'hot' seems to either make the plastic deteriorate, or expansion and subsequent return to normal of the tube makes the joints fail, but this shouldn't be an issue for an antenna.

S O D,

Dave----I don't know where you might buy this pipe but I can tell you why it carries the aluminium when used for plumbing water supplies across a field---yes of course you have guessed now, it provides the very necessary tracer to reduce the risk of ripping it up with deep ploughing

Regards

Brian

Excellent thank you! Michael's link takes me to a nice picture of the stuff:

And David's suggestion of Dekabon aka Synflex looks right too.

AN Other is definitely describing the right stuff - interesting it's commonplace and cheap in Europe and more expensive & unusual in the UK. Pro-warm is about a pound per metre. Possibly our versions are a higher grade for underfloor heating & instrumentation and the household version hasn't caught on here.

Thanks to Brian and Neil but those suggestions don't quite hit the target. In this particular type of broadband antenna the inductance of the loop should be as low as possible whilst enclosing the largest possible area. Consequently the loop should be a single round turn of a large diameter conductor made of either copper or aluminium.

As there are two or four loops in each antenna so I'm looking for about 20 metres, more if I experiment.

Many thanks for the info - now I know it can be bought I can look for bargains!

Cheers,

Dave

PS If anyone has 20 metres of 3" diameter copper tube left over from making a model loco boiler, I'd willingly pay £20 to take it away...

Edited By SillyOldDuffer on 09/12/2018 18:48:14

Edited By SillyOldDuffer on 09/12/2018 18:48:54

Slightly better price here, Dave : **LINK**

https://www.ebay.co.uk/itm/16MM-UNDERFLOOR-HEATING-PEX-AL-PEX-PIPE-FREE-PIPE-STAPLE/142493917788

MichaelG.

I knew the alloy was an oxygen barrier but didn’t know why. Wiki throws up this:

PEX-AL-PEX pipes, or AluPEX, or PEX/Aluminum/PEX, or Multilayer pipes are made of a layer of aluminum sandwiched between two layers of PEX. The metal layer serves as an oxygen barrier, stopping the oxygen diffusion through the polymer matrix, so it cannot dissolve into the water in the tube and corrode the metal components of the system.^[34] The aluminium layer is thin, typically 1 or 2 mm, and provides some rigidity to the tube such that when bent it retains the shape formed (normal PEX tube will spring back to straight). The aluminium layer also provides additional structural rigidity such that the tube will be suitable for higher safe operating temperatures and pressures.

The use of AluPex tubing has grown greatly since 2010 onwards. It is easy to work and position. Curves may be easily formed by hand. Tube exists for use with both hot and cold water and also for gas.

I was told it originated in Germany but I don’t know for sure.

Now we know what you are looking for, it's cheaper at Wickes than on ePay...

www.wickes.co.uk/John-Guest-Speedfit-Polybutylene-Layflat-Barrier-Pipe---White-15mm-x-25m/p/117403

Neil

<edit> Corrected the 'Down Wiv Skule' spelling and grammar...

Edited By Neil Wyatt on 10/12/2018 11:26:28

.

... In what sense is that cheaper than £37 for 50 meters ?

MichaelG.

Don't worry about the price Michael, more of a worry is that Neil has linked to standard pipe with NO aluminium layer

Also note that the Ali stuff is Euro 16mm dia so does not fit our regular 15mm fittings, not a problem for this use.

Edited By JasonB on 10/12/2018 09:50:54

Now that's given me an idea - I live in the country and a farmer has abandoned a few off-cuts of blue pipe after re-plumbing a cattle-trough. If it's aluminised I can try one of the local agricultural suppliers.

Ta,

Dave

.

Most unlikely, I would say

To the best of my [admittedly limited] knowledge ... British farmers use standard MDPE pipe for cattle troughs.

https://www.toolstation.com/shop/Plumbing/d20/MDPE+Pipe+%26+Fittings/sd2729/MDPE+Pipe/p31388

MichaelG.

Edited By Michael Gilligan on 10/12/2018 12:50:15

Thanks Vic, the more brand-names the better. Stuff is so much easier to find when you know what it's called!

My main concern now is that the UK stuff looks to be heavier and more expensive than the thinner version sold abroad. If it's too stiff I might as well use copper pipe. Typical - when you want a basic item you can only find quality and when you want quality you can only find basic...

Dave

Odd! Must have used the wrong link.

This is the one I meant:

www.wickes.co.uk/John-Guest-Speedfit-Plastic-Pipe---15mm-x-3m/p/117407

3m should be enough and it's only £4.71. The photo clearly shows a 3-layer pipe, however if it isn't th right stuff I stand to be corrected.

Neil

<edit> Crickey it's done it again! Hopefully this is now the link I mean. Should be 3m of 15mm pipe.

Edited By Neil Wyatt on 10/12/2018 14:11:40

S-O-D,

You,re looking for 20 m of 3" copper tube,left over ?????????????? I wish you luck !

People have killed for less !

PS I think that blue pipe is the same as the Rednecks use over here,just plain plastic.

That is still not the one with Aluminium in it just polybutylene, as I said above the ali stuff is also 16mm OD not 15mm of the usual plumbing pipe

There is a blue pipe with aluminium core but that is a rigid air pipe not the MDPE stuff for services

Edited By JasonB on 10/12/2018 15:00:11

Dave, don't know where you live, but there's a chap on the Facebook Buxton Selling group with 50m of 15mm underfloor composite pipe for sale @ £20

Bill