I need to fill some metal conduits with something to prevent
condensation forming and running out of the end. The standard answer
for doing this is expanding foam but these conduits are too small for
this to be practical.

For example one of them is about 2cm x 4cm cross section and 40cm or
so long. It has some (12v) cables running through it so there's not a
lot of 'air' left. At the moment both ends are open though the top
end is a little inaccessible. I could drill holes at intervals to get
access in the middle.

So, are there any products that will make it easy to fill this with
something like expanding foam? A 'mini' expanding foam would be OK,
with a tube 2mm or less diameter. ... or maybe something I can pour
in, like potting compound, I can bung up the bottom temporarily while
it cures.

--
Chris Green
·

On 24/04/2024 11:59, Chris Green wrote:
> I need to fill some metal conduits with something to prevent
> condensation forming and running out of the end. The standard answer
> for doing this is expanding foam but these conduits are too small for
> this to be practical.
>
> For example one of them is about 2cm x 4cm cross section and 40cm or
> so long. It has some (12v) cables running through it so there's not a
> lot of 'air' left. At the moment both ends are open though the top
> end is a little inaccessible. I could drill holes at intervals to get
> access in the middle.
>
> So, are there any products that will make it easy to fill this with
> something like expanding foam? A 'mini' expanding foam would be OK,
> with a tube 2mm or less diameter. ... or maybe something I can pour
> in, like potting compound, I can bung up the bottom temporarily while
> it cures.
>
Are you sure that standard expanding foam would not travel down
(or up) the conduit?
You could attach the nozzle to the conduit with duct tape to allow
more pressure to build up and drive the foam through.

John

On 24/04/2024 11:59, Chris Green wrote:
> I need to fill some metal conduits with something to prevent
> condensation forming and running out of the end. The standard answer
> for doing this is expanding foam but these conduits are too small for
> this to be practical.
>
> For example one of them is about 2cm x 4cm cross section and 40cm or
> so long. It has some (12v) cables running through it so there's not a
> lot of 'air' left. At the moment both ends are open though the top
> end is a little inaccessible. I could drill holes at intervals to get
> access in the middle.
>
> So, are there any products that will make it easy to fill this with
> something like expanding foam? A 'mini' expanding foam would be OK,
> with a tube 2mm or less diameter. ... or maybe something I can pour
> in, like potting compound, I can bung up the bottom temporarily while
> it cures.
>

When an elec company do any jointing of underground cables
using a splicing box, it has special plugs on top that they
pour some sort of potting compound into, which is mixed with
an activator immediately prior to use.

John R Walliker <jrwalliker@gmail.com> wrote:
> On 24/04/2024 11:59, Chris Green wrote:
> > I need to fill some metal conduits with something to prevent
> > condensation forming and running out of the end. The standard answer
> > for doing this is expanding foam but these conduits are too small for
> > this to be practical.
> >
> > For example one of them is about 2cm x 4cm cross section and 40cm or
> > so long. It has some (12v) cables running through it so there's not a
> > lot of 'air' left. At the moment both ends are open though the top
> > end is a little inaccessible. I could drill holes at intervals to get
> > access in the middle.
> >
> > So, are there any products that will make it easy to fill this with
> > something like expanding foam? A 'mini' expanding foam would be OK,
> > with a tube 2mm or less diameter. ... or maybe something I can pour
> > in, like potting compound, I can bung up the bottom temporarily while
> > it cures.
> >
> Are you sure that standard expanding foam would not travel down
> (or up) the conduit?
> You could attach the nozzle to the conduit with duct tape to allow
> more pressure to build up and drive the foam through.
>
I have tried once and it didn't even seem to fill the end. It's
difficult to make a duct tape seal as the conduit is flat against a
vertical (steel) wall and is part of it so you can't wrap stuff around
it.

I guess I could drill a series of holes down the conduit big enough for
the expanding foam tube but that does feel a bit drastic!

--
Chris Green
·

Andrew <Andrew97d@btinternet.com> wrote:
> On 24/04/2024 11:59, Chris Green wrote:
> > I need to fill some metal conduits with something to prevent
> > condensation forming and running out of the end. The standard answer
> > for doing this is expanding foam but these conduits are too small for
> > this to be practical.
> >
> > For example one of them is about 2cm x 4cm cross section and 40cm or
> > so long. It has some (12v) cables running through it so there's not a
> > lot of 'air' left. At the moment both ends are open though the top
> > end is a little inaccessible. I could drill holes at intervals to get
> > access in the middle.
> >
> > So, are there any products that will make it easy to fill this with
> > something like expanding foam? A 'mini' expanding foam would be OK,
> > with a tube 2mm or less diameter. ... or maybe something I can pour
> > in, like potting compound, I can bung up the bottom temporarily while
> > it cures.
> >
>
> When an elec company do any jointing of underground cables
> using a splicing box, it has special plugs on top that they
> pour some sort of potting compound into, which is mixed with
> an activator immediately prior to use.
>
Yes, that was the sort of thing I was thinking of, I can just about
access the top of the tube. The 'stuff' would have to be quite liquid
to pour down the conduit.

--
Chris Green
·

Am 24.04.2024 um 13:39 schrieb Chris Green:
> Andrew <Andrew97d@btinternet.com> wrote:

>> When an elec company do any jointing of underground cables
>> using a splicing box, it has special plugs on top that they
>> pour some sort of potting compound into, which is mixed with
>> an activator immediately prior to use.
>>
> Yes, that was the sort of thing I was thinking of, I can just about
> access the top of the tube. The 'stuff' would have to be quite liquid
> to pour down the conduit.
>
https://www.youtube.com/watch?v=OKkqZ0XccAA
Liquid enough?
But fucking expensive. There must be cheaper brands.

Chris Green <cl@isbd.net> wrote:
> John R Walliker <jrwalliker@gmail.com> wrote:
> > On 24/04/2024 11:59, Chris Green wrote:
> > > I need to fill some metal conduits with something to prevent
> > > condensation forming and running out of the end. The standard answer
> > > for doing this is expanding foam but these conduits are too small for
> > > this to be practical.
> > >
> > > For example one of them is about 2cm x 4cm cross section and 40cm or
> > > so long. It has some (12v) cables running through it so there's not a
> > > lot of 'air' left. At the moment both ends are open though the top
> > > end is a little inaccessible. I could drill holes at intervals to get
> > > access in the middle.
> > >
> > > So, are there any products that will make it easy to fill this with
> > > something like expanding foam? A 'mini' expanding foam would be OK,
> > > with a tube 2mm or less diameter. ... or maybe something I can pour
> > > in, like potting compound, I can bung up the bottom temporarily while
> > > it cures.
> > >
> > Are you sure that standard expanding foam would not travel down
> > (or up) the conduit?
> > You could attach the nozzle to the conduit with duct tape to allow
> > more pressure to build up and drive the foam through.
> >
> I have tried once and it didn't even seem to fill the end. It's
> difficult to make a duct tape seal as the conduit is flat against a
> vertical (steel) wall and is part of it so you can't wrap stuff around
> it.
>
> I guess I could drill a series of holes down the conduit big enough for
> the expanding foam tube but that does feel a bit drastic!
>
This (drilling holes) sort of worked, I've made one hole and squirted
expanding foam into it and it has filled a section. However it is
rather difficult to avoid damaging the wires inside as the conduit is
very tightly packed. I need a way to limit accurately how deep the
drill goes and, given where this conduit is (and it's part of the wall
that supports it), that's rather difficult.

--
Chris Green
·

Chris Green <cl@isbd.net> wrote:
> This (drilling holes) sort of worked, I've made one hole and squirted
> expanding foam into it and it has filled a section. However it is
> rather difficult to avoid damaging the wires inside as the conduit is
> very tightly packed. I need a way to limit accurately how deep the
> drill goes and, given where this conduit is (and it's part of the wall
> that supports it), that's rather difficult.

The traditional approach is a rubber band around your drill bit: the drill
stops when it hits the rubber band. It's hard on the rubber bands if doing
many holes so you tend to need a few.

You can also get collars which have a grub screw and clamp to the drill bit.
I have a set of countersink bits where the initial drill is the pilot and
the collar is the countersink, but if you fit the collar backwards then the
blade faces away from the surface and it acts as a depth stop.

Theo

Theo <theom+news@chiark.greenend.org.uk> wrote:
> Chris Green <cl@isbd.net> wrote:
> > This (drilling holes) sort of worked, I've made one hole and squirted
> > expanding foam into it and it has filled a section. However it is
> > rather difficult to avoid damaging the wires inside as the conduit is
> > very tightly packed. I need a way to limit accurately how deep the
> > drill goes and, given where this conduit is (and it's part of the wall
> > that supports it), that's rather difficult.
>
> The traditional approach is a rubber band around your drill bit: the drill
> stops when it hits the rubber band. It's hard on the rubber bands if doing
> many holes so you tend to need a few.
>
> You can also get collars which have a grub screw and clamp to the drill bit.
> I have a set of countersink bits where the initial drill is the pilot and
> the collar is the countersink, but if you fit the collar backwards then the
> blade faces away from the surface and it acts as a depth stop.
>
I tried a collar but since it's steel I'm drilling the pressure
required was too much for the collar to resist. There's absolutely no
way a rubber band is going to help at all.

--
Chris Green
·

On Wed, 24 Apr 2024 20:14:08 +0100, Chris Green <cl@isbd.net> wrote:

>I tried a collar but since it's steel I'm drilling the pressure
>required was too much for the collar to resist. There's absolutely no
>way a rubber band is going to help at all.

How about taking an angle grinder and grinding a small flat on the conduit? With
care, you might grind through the metal, and just scuff the insulation?

And maybe silicone sealant instead of foam -- more pressure on the cartridge
(but less likely to expand along the conduit)?

Thomas Prufer

Thomas Prufer <prufer.public@mnet-online.de.invalid> wrote:
> On Wed, 24 Apr 2024 20:14:08 +0100, Chris Green <cl@isbd.net> wrote:
>
> >I tried a collar but since it's steel I'm drilling the pressure
> >required was too much for the collar to resist. There's absolutely no
> >way a rubber band is going to help at all.
>
> How about taking an angle grinder and grinding a small flat on the conduit? With
> care, you might grind through the metal, and just scuff the insulation?
>
Yes, I have wondered whether that might be a possible approach. I'm
currently exploring approaches from the ends, that may be enough with
a flexible tube on the exanding foam aerosol. If I can seal both ends
then that should stop water coming out of the bottom.

> And maybe silicone sealant instead of foam -- more pressure on the cartridge
> (but less likely to expand along the conduit)?
>
Yes, another possibility, thank you Thomas.

--
Chris Green
·

On 24/04/2024 20:14, Chris Green wrote:
> Theo <theom+news@chiark.greenend.org.uk> wrote:
>> Chris Green <cl@isbd.net> wrote:
>>> This (drilling holes) sort of worked, I've made one hole and squirted
>>> expanding foam into it and it has filled a section. However it is
>>> rather difficult to avoid damaging the wires inside as the conduit is
>>> very tightly packed. I need a way to limit accurately how deep the
>>> drill goes and, given where this conduit is (and it's part of the wall
>>> that supports it), that's rather difficult.
>>
>> The traditional approach is a rubber band around your drill bit: the drill
>> stops when it hits the rubber band. It's hard on the rubber bands if doing
>> many holes so you tend to need a few.
>>
>> You can also get collars which have a grub screw and clamp to the drill bit.
>> I have a set of countersink bits where the initial drill is the pilot and
>> the collar is the countersink, but if you fit the collar backwards then the
>> blade faces away from the surface and it acts as a depth stop.
>>
> I tried a collar but since it's steel I'm drilling the pressure
> required was too much for the collar to resist. There's absolutely no
> way a rubber band is going to help at all.

I have, in the past, removed the Earth terminal from the back of a
socket and used the terminal's own screw to clamp it onto a drill bit,
as a depth stop.

Thomas Prufer <prufer.public@mnet-online.de.invalid> wrote:
> And maybe silicone sealant instead of foam -- more pressure on the cartridge
> (but less likely to expand along the conduit)?

I think you can get liquid silicone rubber - used for making silicone moulds
and stuff.

One thing to be wary of with silicone is the cheap stuff is acetoxy cure,
which means it emits acetic acid (aka vinegar) when curing. That can cause
corrosion, so safer is neutral cure which doesn't.

Theo