I need to re-route the pipe running between the oil tank and my 50kW
boiler. I see that inserts are now recommended in soft copper pipe to
prevent the pipe from distorting - but these reduce the bore of a 10mm
pipe from about 8.6mm to about 6mm. The boiler manual just gives max
pipe run info for 10mm (O/D) and I haven't been able to find any other
info. Any suggestions on where to find further info or how to do the
sums on the effect of a few (6 or 8) 6mm restrictions in an 8.6mm bore?

In article ,
wrote:
I need to re-route the pipe running between the oil tank and my 50kW
boiler. I see that inserts are now recommended in soft copper pipe to
prevent the pipe from distorting - but these reduce the bore of a 10mm
pipe from about 8.6mm to about 6mm. The boiler manual just gives max
pipe run info for 10mm (O/D) and I haven't been able to find any other
info. Any suggestions on where to find further info or how to do the
sums on the effect of a few (6 or 8) 6mm restrictions in an 8.6mm bore?

Don't know anything about oil pipe, but are you saying end feed not
allowed?

--
*TEAMWORK...means never having to take all the blame yourself *

Dave Plowman London SW
To e-mail, change noise into sound.

On 13/05/2021 09:31, wrote:
I need to re-route the pipe running between the oil tank and my 50kW
boiler. I see that inserts are now recommended in soft copper pipe to
prevent the pipe from distorting - but these reduce the bore of a 10mm
pipe from about 8.6mm to about 6mm. The boiler manual just gives max
pipe run info for 10mm (O/D) and I haven't been able to find any other
info. Any suggestions on where to find further info or how to do the
sums on the effect of a few (6 or 8) 6mm restrictions in an 8.6mm bore?


Hmmm, after a bit more thought I'm beginning to realise that this is not
an easy one. Oil is incompressible so *I think* this means that, to a
first approximation, the narrowest bore sets the flow resistance. The
cross-sectional areas will vary as the square of the diameters so that
means the XSA through the insert is about 49% that of the pipe. In
addition to the XSA (and the head) the flow rate will also vary (in some
way) inversely with the internal circumference, but this will be a
linear relationship (about 70%) and only relevant for the percentage
that's restricted, which is insignificant compared to the XSA effect.
I'll now wait for someone to tell me about a link to a relevant graph or
table ...

On 13/05/2021 13:10, wrote:
Hmmm, after a bit more thought I'm beginning to realise that this is not
an easy one. Oil is incompressible so *I think* this means that, to a
first approximation, the narrowest bore sets the flow resistance.
No.
flow through pipes is like current through resistors = the longer and
also the narrower they are the more pressure drop for a given flow rate.

You need to add the 'resistances' all together. So short inserts wont
hurt too much.

The equations that approximate behaviour are friction to the walls. The
larger the bore the more cross section area to surface area there is.
Surface area is 2πR times length, cross sectional area is πR²...so
volume per unit wall area varies as R...

--
The New Left are the people they warned you about.

wrote:
I need to re-route the pipe running between the oil tank and my 50kW
boiler. I see that inserts are now recommended in soft copper pipe to
prevent the pipe from distorting - but these reduce the bore of a 10mm
pipe from about 8.6mm to about 6mm. The boiler manual just gives max
pipe run info for 10mm (O/D) and I haven't been able to find any other
info. Any suggestions on where to find further info or how to do the
sums on the effect of a few (6 or 8) 6mm restrictions in an 8.6mm bore?



Would the use of flared fittings avoid the loss of flow induce by a pipe
insert? I guess youd need a flaring tool but you cant have too many
tools. ;-)

https://www.bes.co.uk/heating-ventil...flare-fittings

Tim

--
Please don't feed the trolls

On 13/05/2021 13:28, The Natural Philosopher wrote:
On 13/05/2021 13:10, wrote:
Hmmm, after a bit more thought I'm beginning to realise that this is
not an easy one. Oil is incompressible so *I think* this means that,
to a first approximation, the narrowest bore sets the flow resistance.
No.
flow through pipes is like current through resistors = the longer and
also the narrower they are the more pressure drop for a given flow rate.
OK, I'll need to think some more about that.

You need to add the 'resistances' all together. So short inserts wont
hurt too much.

The equations that approximate behaviour are friction to the walls. The
larger the bore the more cross section area to surface area there is.
Surface area is 2πR times length, cross sectional area is πR²...so
volume per unit wall area varies as R...
Thanks, but that's effectively what I said in the bit you snipped

On 13/05/2021 13:46, Tim+ wrote:
wrote:
I need to re-route the pipe running between the oil tank and my 50kW
boiler. I see that inserts are now recommended in soft copper pipe to
prevent the pipe from distorting - but these reduce the bore of a 10mm
pipe from about 8.6mm to about 6mm. The boiler manual just gives max
pipe run info for 10mm (O/D) and I haven't been able to find any other
info. Any suggestions on where to find further info or how to do the
sums on the effect of a few (6 or 8) 6mm restrictions in an 8.6mm bore?



Would the use of flared fittings avoid the loss of flow induce by a pipe
insert? I guess youd need a flaring tool but you cant have too many
tools. ;-)

https://www.bes.co.uk/heating-ventil...flare-fittings

Tim

It would, and that had been Plan A, but I'd discounted it because one of
the points (the end of the existing pipe) would be impossible to get to
with a flaring tool ... and I don't have a flaring tool

On 13/05/2021 09:31, wrote:
I need to re-route the pipe running between the oil tank and my 50kW
boiler. I see that inserts are now recommended in soft copper pipe to
prevent the pipe from distorting - but these reduce the bore of a 10mm
pipe from about 8.6mm to about 6mm. The boiler manual just gives max
pipe run info for 10mm (O/D) and I haven't been able to find any other
info. Any suggestions on where to find further info or how to do the
sums on the effect of a few (6 or 8) 6mm restrictions in an 8.6mm bore?

Flow resistance is normally proportional to the the product of the
length and the per unit flow resistance. So a short narrowing does not
have the same resistance as a complete pipe length at the reduced diameter.

I expect you can treat it in much the same way one would for gas pipe
sizing where each restriction can be treated as having an equivalent
length of nominal pipe. Say a heuristic like, each insert adds the
equivalent of an extra 50cm of pipe. (no idea what that length would be
for oil though!)





--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

wrote:
On 13/05/2021 13:46, Tim+ wrote:
wrote:
I need to re-route the pipe running between the oil tank and my 50kW
boiler. I see that inserts are now recommended in soft copper pipe to
prevent the pipe from distorting - but these reduce the bore of a 10mm
pipe from about 8.6mm to about 6mm. The boiler manual just gives max
pipe run info for 10mm (O/D) and I haven't been able to find any other
info. Any suggestions on where to find further info or how to do the
sums on the effect of a few (6 or 8) 6mm restrictions in an 8.6mm bore?



Would the use of flared fittings avoid the loss of flow induce by a pipe
insert? I guess youd need a flaring tool but you cant have too many
tools. ;-)

https://www.bes.co.uk/heating-ventil...flare-fittings

Tim

It would, and that had been Plan A, but I'd discounted it because one of
the points (the end of the existing pipe) would be impossible to get to
with a flaring tool ... and I don't have a flaring tool


Ive no idea how accurate the flaring has to be but I would have thought
that as long as its €œnear enough for the fittings to bolt together the
compression forces with mould the pipe into the correct shape to seal.

(Pure supposition on my part. Could be wrong but Id be tempted to try it
personally. Those with more knowledge of flared fittings on copper might
advise otherwise).

Tim

--
Please don't feed the trolls

In article
,
Tim+ wrote:
I‘ve no idea how accurate the flaring has to be but I would have thought
that as long as it‘s ”near enough for the fittings to bolt together the
compression forces with mould the pipe into the correct shape to seal.

I doubt it. I have a flaring tool for car brake pipes. There's more to it
than just flaring it out a bit. It forms a sort of nipple on the end.

--
*The beatings will continue until morale improves *

Dave Plowman London SW
To e-mail, change noise into sound.

On 13/05/2021 09:31, wrote:
I need to re-route the pipe running between the oil tank and my 50kW
boiler. I see that inserts are now recommended in soft copper pipe to
prevent the pipe from distorting - but these reduce the bore of a 10mm
pipe from about 8.6mm to about 6mm. The boiler manual just gives max
pipe run info for 10mm (O/D) and I haven't been able to find any other
info. Any suggestions on where to find further info or how to do the
sums on the effect of a few (6 or 8) 6mm restrictions in an 8.6mm bore?


You might be able to find more info from Danfoss as they make many of
the pumps, or Reillo.

The manual for my Camray Heatslave boiler has details for 10mm and 12mm
OD pipe. The max pipe length depends on the head, i.e. how much the
bottom of the tank is above or below the oil pump. I used flare
fittings when I installed a new boiler some years ago now. It may be
that you can flare the end of the pipe before pushing it into its final
position. I recall bending my pipe round a small pulley wheel.

The new boiler came with compression joints for the oil supply flow and
return.

--
Michael Chare

On 13/05/2021 16:49, Dave Plowman (News) wrote:
In article
,
Tim+ wrote:
I€˜ve no idea how accurate the flaring has to be but I would have thought
that as long as it€˜s €�near enough for the fittings to bolt together the
compression forces with mould the pipe into the correct shape to seal.

I doubt it. I have a flaring tool for car brake pipes. There's more to it
than just flaring it out a bit. It forms a sort of nipple on the end.


For 10mm copper oil pipe there is no such nipple the nut that goes onto
the pipe first has a female thread which screws into the male thread of
what ever the pipe is connecting to.


--
Michael Chare

On 13/05/2021 14:11, John Rumm wrote:
On 13/05/2021 09:31, wrote:
I need to re-route the pipe running between the oil tank and my 50kW
boiler. I see that inserts are now recommended in soft copper pipe to
prevent the pipe from distorting - but these reduce the bore of a 10mm
pipe from about 8.6mm to about 6mm. The boiler manual just gives max
pipe run info for 10mm (O/D) and I haven't been able to find any other
info. Any suggestions on where to find further info or how to do the
sums on the effect of a few (6 or 8) 6mm restrictions in an 8.6mm bore?

Flow resistance is normally proportional to the the product of the
length and the per unit flow resistance. So a short narrowing does not
have the same resistance as a complete pipe length at the reduced diameter.

I expect you can treat it in much the same way one would for gas pipe
sizing where each restriction can be treated as having an equivalent
length of nominal pipe. Say a heuristic like, each insert adds the
equivalent of an extra 50cm of pipe. (no idea what that length would be
for oil though!)


I haven't found any info about "equivalent length", or any quantitative
guidance, but the boiler manufacturer doesn't foresee any problems so
I'll stop thinking about it. It's been pushed-down the job stack by
other things but I'll plan to get to it in the warmer weather in case
there are problems.