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?
LDPE and HDPE Black BS1972: 1967 C&D BS3284 C&D BS1972: 1961 (IS134 NG & HG)
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.
Probably.
Can it not be used
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
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.
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.
External OD (Overall Diameter).
Does it have thick walls?
Relative to what? Relative to copper pipe, yes.
Is that why it does not
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.
You didn't look further down the BES page you were on then?
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got to MDPE pipe fittings page (page 198) and scroll down to product 9951
You may also wish to look at this pdf from Polypipe:
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.
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