Alkathene to MDPE connection

[Kes]

The main water feed as it arrives under my drive is in black poly (what I call Alkathene), marked S & L Polythene BS1972 Class C 1". (It is currently reduced down to 3/4" and gets blocked by debris at the point of reduction.) I need to extend into the house in 32 mm MDPE and also pick up a 3/4" Alkathene feed to the outhouses.

I intend to use Philmac Metric/Imperial fittings, a 32mm/1" coupler to join the Alkathene to the 32mm MDPE, then after a few feet of MDPE a Metric/Imperial tee 32mm/1" x 32mm/1" x 25mm/3/4" to connect to the 3/4" Alkathene. Then 32 mm MDPE into the house.

Before I rush in I have a few questions.

Is Met/Imp the correct range to use for the above?

Should I use Polygrip Plus for the MDPE connections in the house, or continue with Met/Imp?

How much degradation of the Alkathene can these fittings stand, and still be watertight? The main Alkathene pipe has been 'accessed' a few times before by previous owners, so is fairly scratched. Should I try to excavate further to find a more virginal section? (I'm not sure that one exists.) This is low pressure gravity fed supply.

Rgds.

 

[powell30]

Why does a 3/4 inch pipe block with debris?? I would suggest that what you need is a filtration system at the point water enters the pipework. It will continue to silt, just take longer to block. By all means upgrade the line but if debris is entering the system you will block again eventually. Philmac imp/mets are fine. Whether you then use polygrip inside is moot really as you can come off in 22mm copper once inside.

 

[Kes]

Thanks for the reply. It's a private water supply that comes from an underground spring into a collection tank about 2-300 yards away. At some point a previous owner decided to reduce the feed pipe from 1" to 3/4" somewhere under the house drive (which I have labouriously dug up).

The collection tank is inaccessable for any sort of filtration. One benefit of this free water supply is that occasionally a frog or two will venture down the pipe. The small ones make it to the house filtration and can be removed with only a little swearing. The larger ones get stuck at the reduction coupler under the drive, which increases the swearing by a huge factor. We are then left with no water supply. I usually get round this by piping water from the tap in the greenhouse (on the feed side of the blockage) and waiting for the stuck frog to rot, which can take weeks. This is not very appetising.

So I am attempting to run an 1" feed all the way into the house so that I can rig up a bypass system to flush out any 'debris', or alternatively be able to clear the frogs more easily, with the minimum of swearing.

I shall have to use 1" inside the house with ball valves so that these fat b****s don't get stuck anywhere. I plan to take the 1" straight out again, with a 22mm feed off to the filtration system, so I can occasionsally flush the pipework without any disconnection.

Any comment on using Philmac on scratched pipe? Rgds.

 

[powell30]

Kes,

Ok, i understand.....townie who doesn't suffer 'frog' problems. Just one thing. Do you steralise the water in any way ..... can't see dead frogs passing the water regs test for 'pottable' water!! Depends on the depth of the scratches as to whether you will get a seal. I doubt you will have 'high' pressure on the supply side if tank fed but if in doubt wrap the pipe with ptfe or masking tap etc to 'smooth' the pipe. Should work. Just don't bury the pipe till you test!. Another trick maybe to replace and then cover the pipe with pea gravel. Ths will help prevent scratching in future.

 

[Softus]

Any comment on using Philmac on scratched pipe? Rgds.

MDPE is almost always scratched, because it's almost always installed by builders who almost always scratch it.

MDPE is soft, so if a scratch is shallow then you can often gently drag a stanley knife blade in the direction of the groove and by that means smooth the 'peaks' back into the 'trough'.

If the scratch is deeper, and more of a gouge, then I would cut back and introduce a coupling rather than risk a leak.

Don't forget to use inserts.

I doubt you will have 'high' pressure on the supply side if tank fed...

Depends on the height of the tank, n'est-ce pas?

It has only to be three times the height of yer average house gutter and you'll have 1.5 bar - not a low figure for a mains supply.

And private supplies are often pumped anyway.

 

[powell30]

Softus, compared to mains supply i doubt the OP has high pressure. And if pumped then why frogs in system?? If they had gone through a pump not a lot would be left to block!! Accepted he may have say 1.5 bar....but still not mains pressure.....good idea with the knife tho.....i use a nail file to smooth out smaller ones.

 

[Softus]

Softus, compared to mains supply i doubt the OP has high pressure.

You already said, or implied, that you doubted it.

And if pumped then why frogs in system?

I didn't say that I thought Kes' supply was pumped; I was merely underlining my point, i.e. it's wrong to assume anything about the pressure of a tank-fed private supply.

Accepted he may have say 1.5 bar....but still not mains pressure.

Welll then, let's get specific - what do you call mains pressure?

....good idea with the knife tho

Thank you.

i use a nail file to smooth out smaller ones.

Surely that would remove material, rather than redistribute it?

 

[powell30]

Softus, apologies, we seem to be drifting off subject. Your points are valid. But so are mine. philmac fittings are very good for getting seals onto all sorts of piping. I find them more forgiving than usuall mdpe connections. Better sometimes than say leadloks....very fiddly filing and shaving to get the blighters to fit......and then flattening one side too much grr.....i would suggest without seeing the pipework philmacs will seal up fitstime unless the piping is scared badly.

oh, and 1.5 bar is low mains pressure.....acceptable but low.

 

[Softus]

Softus, apologies, we seem to be drifting off subject.

No we're not. The subject it "comments on Philmac on scratched MDPE".

Your points are valid. But so are mine.

Your point about mains pressure isn't valid until you say what you think mains pressure should be.

philmac fittings are very good for getting seals onto all sorts of piping.

What?! What do you mean "all sorts"?

I find them more forgiving than usuall mdpe connections.

What do you mean by a "usual" MDPE connection?

Better sometimes than say leadloks....very fiddly filing and shaving to get the blighters to fit......and then flattening one side too much grr.....i would suggest without seeing the pipework philmacs will seal up fitstime unless the piping is scared badly.

I don't know about that MDPE, but you're scaring me. A leadlok? On MDPE? Why?

oh, and 1.5 bar is low mains pressure.....acceptable but low.

Well what do you call "unacceptably low", and what do you call "unacceptably high"?

And at pressure what do you think your own water provider is legally obliged to deliver water to you?

 

[powell30]

Ok, we seem to be heading towards a points scoring rather than a help the OP here Softus. In my area (South Staffs Water) minimum requirement is 1 bar......i have seen less than this occasionally (due to high demand......yeah) but most times 2-3.5 bar is 'normal' here. Therefore, 1.5 bar is towards the low end of working pressure here. Obviously, you are correct, a tank could be 10,15,20 meters hight etc etc.......but as it is 'tank fed' i would guess it's not more than 1.5bar.
oh, if you wish to be pedantic, leadlok on lead....of course. But i use philmac connections if i can....that was all i was refering to. Your points, and views are of course valid and i bow to greater experience if you so have it. I was just trying to help the op......silly me.

 

[Kes]

Thanks for all the interest, I think I have it sussed now.

The collection tank is up in the roaming hills a few hundred yards away. It is a rather grotty steel closed horizontal cylindrical tank half set into the ground. You certainly wouldn't drink from what flows out of the 4" inspection hatch on the top. The pipework is buried and there is no real access to the tank. In any event I don't know who owns it, it's on somebody else's land, and it would cost a fortune to redo properly. So this sleeping dog can lie.

When one stands next to the tank the roofline of the house in the distance seems to be more or less on the same level, so there's no great force behind the flow. There's enough to supply the cold feed tank in the roof, but I wouldn't call it gushing. That's propably why the toilets and cold taps upstairs are fed from the cold feed tank, not the 'mains'. It's not too bad downstairs, but not enough pressure to use a garden sprinker with any success. There is no pump.

In the house there is a 5-micron sediment filter, a granulated carbon odour filter, and a UV bug zapper. After the filters there's about 5 ltrs a min flow, perhaps better with clean filters. I think it's about 12 ltrs a min unfiltered. Pressure must be minimal.

 

[Softus]

Ok, we seem to be heading towards a points scoring rather than a help the OP here Softus.

I fundamentally disagree.

Firstly, my goal is accuracy, not points scoring. If that assists someone here then it's a bonus, but without accuracy any attempt at help is pointless. For this reason all guesses, assumptions and vaguenesses are to my goal as the anti-Christ is to Christian doctrine.

Secondly, scratches on MDPE raise only one question: will it or won't it leak? The higher the pressure the greater the likelihood, therefore a discussion of what the pressure is is highly relevant.

Put these two points together and pinning down your definition of "low pressure" becomes of paramount and pressing importance. However...

As it turns out, Kes' water pressure is what most people would call "dribbling" - a grade lower than "low".

......silly me.

You weren't being at all silly. Right up until the moment you started with the sarcasm.

After the filters there's about 5 ltrs a min flow, perhaps better with clean filters. I think it's about 12 ltrs a min unfiltered. Pressure must be minimal.

Kes, surely you would really REALLY benefit from an accumulator?

 

[gas4you]

Softus, I cannot but feel drawn to your posts when I see your name on them.

It always brightens my day and as ever you always seem to be able to alienate anyone who crosses your internet pathway

 

[Softus]

Aw shucks, Dave; you spoil me with your compliments.

 

[powell30]

As i said.....seems we both ended up right. And you are/were smart enough to see where my low pressure/high pressurre coments were going. Yes, at the pressure the OP has he will/should have little problems sealing joints.

And on a final note....philmac do a universal coupler Softus......designed to marry many different materials. Lead included. and as long as you have the correct insert i have yet to see a 'plastic' one they can't couple too.....we friends now or do i use my nail file to sharpen my claws.....no sacarsm intended or infered, just a jest.