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benncool
27-06-2003, 10:44 PM
Here is one for you English guys.

Here in the US we use refrigeration copper pipe and tubing that is measured on the out side dimension OD. While the plumbers and hydronic heat installers use copper pipe that is measured by the inside dimension.

EG. 1 1/8 in. OD refrigeration pipe is equal to 1 in ID water line copper.
1 3/8 OD is equal to 1 1/4 ID.


So this is a 2 part question.

First. Does your refrigeration industry use the OD/ID dimensions as we do here in the States?

Secondly, Our common size pipe is 1/4, 3/8, 1/2, 5/8, 3/4, 7/8, 1-1/8 etc. If you convert 1-1/8 pipe to metric it comes out to 28.57mm. I'm sure they wouldn't use such a clumsy number for pipe. So what are the common mm sizes?


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Essayons

Andy
27-06-2003, 11:30 PM
Hi Benncool:)
same as you mate, right up to 4 1/8":D Then we fit our gauges and read off in deg C. I personally use deg and p.s.i.g, but most use bar.
Mixed up or what:confused:
Regards. Andy:)

Dan
28-06-2003, 01:13 AM
I think things manufactured in inches will always best be described in inches. But copper pipe and bolt sizes are not all manufactured in inches, and there we will be stuck with measuring them by their standards, whether it is a bolt for a Honda or copper made in Siberia.

Measurements, however stand apart. I still don't understand which says it more accurately: 22/7 or 3.14285 ad infinitum.

1/3 or .33333333333333333 etc.

Measuring pipe on the outside versus the inside has always puzzled me. My thinking is that copper pipe has limited wall sizes and for some reason the outside diameter is more important to manufacturers and engineers.

Inside of the pipe is important to flow. Outside of the pipe can vary according to pressure demands, material and other specifications not so easily reined in? Hmmm. I know there is a good reason, but regrettably it is one that I am damned if I know.

benncool
28-06-2003, 04:58 AM
Well I think I understand why we are concerned with the outside surface of a pipe. Except for the condenser. The heat transfer is going from the out side in . So the out side is more important to the refrigeration engineer that it would be to an engineer concerned with "water" flow. My guess!!

No wait even the condenser. The outside surface is important for heat transfer.

herefishy
28-06-2003, 10:32 PM
I beleive that perhaps it is so that you don't accidentally get supplied with "type M" drain tubing to install on the R-404A refrigeration system. :D

Or maybe, when you ask for 7/8" hard-drawn, and the counterman looks at you funny, then you suddenly realize that your in the plumbing shop... Not the refrigeration warehouse.... LOL!

but I don't really know. :)

baker
04-07-2003, 06:43 AM
In Australia, we use imperial tube but with metric names. Three eighth tube, for example, is known as 9mm. This is ok until you get a bit of Italian kit where 9mm means 9mm, while Australian 9mm actually measures 9.525mm.

I don't know how accurate this is, but I believe that tube is referred to by its outside diameter, while pipe is referred to by its inside diameter.

Mark Baker

benncool
04-07-2003, 09:01 PM
Originally posted by herefishy

Or maybe, when you ask for 7/8" hard-drawn, and the counterman looks at you funny, then you suddenly realize that your in the plumbing shop... Not the refrigeration warehouse.... LOL!

but I don't really know. :)

There is a lot of truth in that statement. First you have to get a counter man who can speak American then you have to see if he can speak refrigeration.

I can see on this site that people don't have any problems with speaking refrigeration. :)

Brian_UK
04-07-2003, 10:48 PM
I don't know whether it has changed yet but when the UK first went over to metric pipe sizing for 'water' piping they couldn't make all of the numbers match :-
15, 22, 25, 32, 40, 50, 2 1/2, 75, 100 etc
that old 2.5" pipe at 63 mm just wasn't right so they kept it at 2.5"; you just beat us old Brits can you ?

Another thing, bear in mind that most 'fridge tubing whenever a fitting is used the tube gose 'inside' the fitting. If the size was ID then all hell would break loose.

Dan
05-07-2003, 01:38 AM
Interesting differences about how we describe and measure things, yet somehow fit them all together.

Latte
05-07-2003, 02:41 PM
Dont Know if its related but has anyone else out there noticed that the suction & discharge pipes on some compressors seem to have got slightly smaller. I am only talking about small compressors (electrolux/Aspera/L'unite) about 1-2HP.
I am getting fed up of ordering a replacement compressor and finding although the pot is exactly the same as fitted i am having to flare the pipe. Is this do to manufactures changing from imperial to metric or am i just losing the plot.

Brian_UK
08-07-2003, 10:58 PM
Originally posted by rdocwra
..... i am having to flare the pipe. Is this do to manufactures changing from imperial to metric or am i just losing the plot.

No, they are just being damned awkward :D