Hi,

I was looking in the BES catalogue and saw they sell mdpe pipe and
fittings. It mentioned the fittings could be used with ldpe and hdpe
pipe too but it doesn't seem to sell those. When are ldpe and hdpe
pipe used?

BES sell two colours of mdpe pipe: blue and black. I've only seen the
blue stuff before. I think the catalogue says that blue pipe is used
underground and black above ground. Have I got that right?

Is this because the blue pipe is not UV stable? Can it not be used
above ground? I'm guessing blue has to be used underground as a colour
code because a black pipe could be anything?

Is the main use of mdpe to bring the water from the pavement into the
house? What other times is it used?

When the catalogue says it is 20mm or 25mm, are these internal or
external diameters? Does it have thick walls? Is that why it does not
freeze because the walls are too thick to burst?

How do you cut it, surely not with a hacksaw

TIA

Fred wrote:
Hi,

I was looking in the BES catalogue and saw they sell mdpe pipe and
fittings. It mentioned the fittings could be used with ldpe and hdpe
pipe too but it doesn't seem to sell those. When are ldpe and hdpe
pipe used?

LDPE and HDPE pipes are obsolete types.

LDPE and HDPE Black
BS1972: 1967 C&D BS3284 C&D
BS1972: 1961 (IS134 NG & HG)


BES sell two colours of mdpe pipe: blue and black. I've only seen the
blue stuff before. I think the catalogue says that blue pipe is used
underground and black above ground. Have I got that right?

BS 6572 : 1985
Blue polyethylene pipes up to nominal size 63mm for *below* ground use
for potable water.

(Polypipe lists their blue pipe as suitable up to 20 deg. Centigrade,
which is the upper limit by any reasonable yardstick for cold water.)

BS 6730 : 1986
Black polyethylene pipes up to nominal size 63mm for *above* ground use
for *cold* potable water.



Is this because the blue pipe is not UV stable?

Probably.

Can it not be used
above ground?

Not in direct sunlight. Which is to say, yes blue can be used above
ground if contained in suitable ducting.

I'm guessing blue has to be used underground as a colour
code because a black pipe could be anything?

Or, looking at it the other way, black has to be used above ground
because it is UV resistant.

I don't have copies of the above British Standards to hand, so can't
comment further.


Is the main use of mdpe to bring the water from the pavement into the
house? What other times is it used?

It is used extensively in industrial sites, farms, horticulture
(glasshouses, nurserys), golf courses, sports stadia, football pitches,
allotments, camping and caravan sites, etc to distribute potable water
between buildings, and from buildings to drinking troughs (for
livestock), irrigation systems, sprinklers, automatic garden watering
systems, and to provide stand-pipes for drinking water and or hosepipes,
etc.


When the catalogue says it is 20mm or 25mm, are these internal or
external diameters?

External OD (Overall Diameter).


Does it have thick walls?

Relative to what? Relative to copper pipe, yes.

Is that why it does not
freeze

Who says it doesn't freeze?

because the walls are too thick to burst?


I very much doubt that the walls are too thick to burst. One or two of
the group's resident farmers may care to comment from their experiences.

How do you cut it, surely not with a hacksaw


You didn't look further down the BES page you were on then?

www.bes.co.uk got to MDPE pipe fittings page (page 198) and scroll down
to product 9951

TIA

You may also wish to look at this pdf from Polypipe:

http://preview.tinyurl.com/23onqpj

On Mon, 09 Aug 2010 14:59:21 +0100, Dave Osborne
wrote:


Does it have thick walls?

Relative to what? Relative to copper pipe, yes.

So would a 20mm MDPE pipe have a similar bore to a 15mm copper pipe,
and 25mm MDPE would be used where you would use 22mm copper?

You may also wish to look at this pdf from Polypipe:

http://preview.tinyurl.com/23onqpj

Thanks for all the information. very interesting.

Fred wrote:
On Mon, 09 Aug 2010 14:59:21 +0100, Dave Osborne
wrote:


Does it have thick walls?

Relative to what? Relative to copper pipe, yes.

So would a 20mm MDPE pipe have a similar bore to a 15mm copper pipe,
and 25mm MDPE would be used where you would use 22mm copper?


Yes and yes.

Google is your friend:

http://www.pipestock.com/mdpe-pipes-...pe-blue/?cat=1

Judging by the general descriptions on the above site, blue pipe and
black pipe are identical in specification and price, but for the fact
that blue pipe is blue so if you dig it up you can identify it as a
potable water pipe and black pipe is black for UV resistance.

This means that you can mix and match in the same "system" by running
all your underground feeders in blue and then teeing off to black to go
above ground.