Is this tube OK for R410A?

[smileypete]

Hi,

I'm planning to get some 1/4" and 3/8" tube for a R410A split from here:

http://www.bes.ltd.uk/products/084a.asp

Part nos #13998 and #14575 (15 m coils)

Is this OK for R410A? It states it's made to BS 2871 : Part 2.

Just that it seems a little thin at 22SWG for the 1/4" and 21SWG for the 3/8".

Also what would be a sensible bend radius? I was planning to bend it around some appropriate diameter pipe as it's soft copper and so less likely to kink I'd expect.

Thanks in advance,
Pete.

[frank]

Hi Pete

I went into NRS (Climate Centre) recently and asked if their soft coiled copper was suitable for the higher pressures of R410a. The manager didn't know what I was talking about.

We've still been buying the copper though with no ill effects. Maybe the systems haven't been working up to maximum pressures yet but we haven't had any failures so far.

[Brian_UK]

I wonder Frank - does the 410 kit expand at the condensing unit or is the high pressure pushed down to the evaporator ?

[frank]

I wonder Frank - does the 410 kit expand at the condensing unit or is the high pressure pushed down to the evaporator ?

On the splits it is at the cond unit but on VRV it is at the indoor unit.

No bulges in the pipes so far

[chemi-cool]

Guys,
Acopper tube can hold more then 2000psi before it will burst.

R22 at 43 out temp in a Chinese split, have the same head pressure that an R 410 split in the UK.
No problems with the tubes.

Chemi

[BritCit_Juve]

I got a sheet from HRP which gives the safe working pressures of their copper tube and also shows which they recommend for use with R410A.

I have scanned it and would attach it but it exceeds the 100kb limit. I have got it lower but it is then unreadable.

I have attached it anyway. You can always get the original from HRP

It isn't safe to say that all pipe will take 2000psi as it depends on the thickness at its thinnest point. A tube that has been bent will be thinner on the outer radius. If the material is also border line on thickness in the first place and is low quality then on a hot day with an overcharged system you could exceed the burst pressure at the weak point.

[Argus]

I got a sheet from HRP which gives the safe working pressures of their copper tube and also shows which they recommend for use with R410A.

.

Is this the one?

http://www.hrponline.co.uk/documents...dInfo18xls.pdf

It?s a few years old, (2000) but mainly still relevant. (BS 4434 is now withdrawn).

Try contacting the pipe manufacturers. One of the biggest worldwide is Outokumpu.

http://www.hrponline.co.uk/documents...dInfo18xls.pdf

They have offices in the UK and should be able to help with queries.

Generally speaking, refrigeration copper tube off the shelf is suitable for the pressure criteria outlined in EN 378, part 2, up to about 1 1/8 OD, but it?s best to talk to the manufacturers to be certain.

You need to know if you are within the scope of the PED.


Good luck
________
Ford Mustang Mach 1

[Sir Josiah Sodd]

Searching through Old Sodd’s Big Book of Practical Jottings, I came across this formula for working out the pipe wall thickness that was circulating some years ago.

I can’t remember where I stumbled across it, but it seems to do the trick.

t = [p x d] / [p + (20 x f)]

t Minimum wall thickness (mm)
p Allowable Pressure (ps) (barg)
d OD of the tube
f Design stress

The design stress relates to the material and is expressed as a number (N/mm2). The one used for anealed copper tube by convention, as I recall, is 41N/mm2. But it’s worth checking this. Usually the pipe manufacturer should tell you.

If you’re using a Zeotrope, I suggest that you select the Dew point pressure.

Bending the tube will affect the stress value on the radius. It’s best to use fittings. I think that's been alluded to before.


.

[smileypete]

Hi,

Thanks for all the replies, looks like it will be fine.

I'll keep any bends to 6" radius, that would give a maximum thinning by 7% on the outside of the 3/8" tube, though I'd expect the inside of the bend to get a bit thicker too.

After all the stuff is supplied in coils, so bending it can't be too bad

The HRP chart for 3/4" 18/19 SWG shows a 20% decrease in safe working pressure for a 20% decrease in thickness from 19 SWG to 18.

So I'd expect bending 3/8" with a 6" radius should give up to 7% decrease in safe working pressure which should be fine.

cheers,
Pete.

[BritCit_Juve]

Hi Argus

The sheet I tried to scan is dated March 2005 so I assume it has been updated.
Generally though the info will be the same as you have already got.

Brit

[Argus]

Hi Argus

The sheet I tried to scan is dated March 2005 so I assume it has been updated.
Generally though the info will be the same as you have already got.

Brit

Thanks, Brit

I found my link on HRP?s web site yesterday. It?s listed as issue 18, dated 2000.
There does not appear to be a newer one that I can see, though I would appreciate a copy if possible.

It?s as well to have the most up-to-date, as the PED has come in since then and the old standard is no longer in use. The requirements are basically the same, but none the less it is out of date. (Why don?t companies keep information on their web sites current?)

Have you got a link for the new one?

One interesting point is the arbitrary choice of the two ambient conditions as a basis for the minimum allowable pressure value.
HRP appear to base theirs on the lower ambient, 32 deg, while a previous poster in the forum quotes a Daikin dealer as recommending using a pressure corresponding to the higher condition of 43 deg. There?s a difference of over 8 bar on R 410A.


Argus
________
vaporizer manufacturer

[BritCit_Juve]

Hi Argus

The new one isn't online that I can see.
If you let me have your email address I will send it. Its 364kb so I can't post it here.
Alternatively contact HRP and request a copy of their Counterparts issue 142. Its dated March 2005

BritCit_Juve

[BritCit_Juve]

Ref the ambient choices. HRP don't sell internationally and other than London (all that hot air from westminster) the UK struggles to get anywhere neer 32°C. I suppose therefore they believe the lower limit is safe. Daikin on the other hand sells to the whole world so they need to cover the higher extremes of temperature. To publish the data correctly for every country would be expensive in both time and resources and with copper tube suppliers to do the job Daikin only need to cover their butts for the 99th percentile condition.

BritCit_Juve