Automotive Air Conditioning Information Forum

Topic title search for “pipe”
https://www.autoacforum.com/search.php? ... mit=Search
Searched for tube, tubing, hard line, line came up empty or no results flagged as term too common

Pipe/tube/tubing/hard line vs Hose and related

BTW - what is the common/proper term in MVAC?

When is pipe a better choice in a design than hose?

I can get that hose is needed in areas needing flexibility like between engine and chassis. What other considerations are there?

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Some thoughts from my novice brain - please comment; shoot holes in these, thanks!

Long runs, pipe is more efficient, no sags, easier mounting points

Pipe is smaller diameter so can fit in spaces hose can’t.

Pipe can act like additional condenser – good

Pipe may have to be insulated to avoid sweating – maybe bad if one is choosing pipe for lower diameter size

Pipe is less expensive – is that true?

Pipe can be bent to tighter radii

Pipe can be joined with flare fittings avoiding welding fittings. I’ve read that there are differences in flare angle and that both copper and aluminum (definitely aluminum) can be “after flared” by the fitting when tightening if the flare angle is slightly different

Aluminum vs copper – why use one vs the other?

Other points?

Thanks

Bump....Would love to get some feedback as I consider the layout for the project.

Thanks

Any reason(s) not to use copper hard line in a custom install?

Tried getting theoretical on this in the Procedures, Tips and FAQ section "Hose vs. Pipe/tube/tubing/hard line and related" https://autoacforum.com/viewtopic.php?t=14877

didn't get any response in a few weeks so asking a simpler question here.

Any reason(s) not to use copper hard line in a custom install?

I've looked a bit into aluminum pipe but the longest sections seem to be 5ft and some of my runs would be longer. Maybe there is coiled aluminum pipe available?

Thanks

Some evap cores are made of copper. Automotive-related, Nothing I've ever seen uses copper for the high side.

^ Thanks Tim. That makes it a valid option. Though I have since found some rolled aluminum coils so will likely go that way.

It would still be great to know about hard vs. flex things to consider. If anyone has any thoughts or opinions, please post here or in the theory thread. The only thing I can think of is condensation on the Evap>compressor line for which one might want to insulate that section.

Pipe vs. flex thread - https://www.autoacforum.com/viewtopic.php?t=14877

Thanks for the reply.

Looks like copper may be a viable pipe choice. Seems rolls of aluminum are also available these days and that seems to be more of the automotive standard.

Following is from a different thread on a related subject

https://www.autoacforum.com/viewtopic.p ... 019#p28019

Tim wrote: ↑Tue Sep 12, 2023 6:32 pm Some evap cores are made of copper. Automotive-related, Nothing I've ever seen uses copper for the high side.

Copper is used in stationary units. Rarely flared, usually brazed. 50 foot coils of copper refrigeration tubing are expensive. And copper lines can be prone to cracking from vibration.

Flared fittings are the devil. I have installed and serviced hundreds of high quality aircraft flare fittings. They are leak prone even at that quality level. Torque sensitive, metal to metal seal. Bad enough with liquids, worse with gasses. They work loose from pressure cycles, thermal cycles and vibration. Any time I find a class 8 truck with no refrigerant and a flare fitting compressor I can bet on a loose flare nut.

OEM systems use aluminum tube in some places. Mostly rear A/C systems where the diameter is small. You will never see a flare fitting on those lines. The OEM lines usually have a rubber hose crimped on the aluminum line to reduce stress on the line.

Barrier hose is not that expensive. It is available cut to length. Good fittings are available. O ring fittings are extremely reliable. a finger tight nut will seal - yes it still needs to be tightened. Use standard hose. Reliable and tough.

You need 3 sizes.

-6 size for the liquid from the bottom of the condenser, to the receiver dryer and on to the evaporator

- 8 size for the high pressure gas from the compressor discharge to the top of the condenser.

-10 size for the suction line from the evaporator to the compressor inlet.

I did not post a comment to this thread.

^ "Flared fittings are the devil."

Thanks for that real world feedback. The auto ac part houses offer flared fittings so one would think they were ok for the application. Nothing better than reports from the field.

I get that oring fittings are better and easier connections if a pipe has such ends and I had high hopes for diy flared fittings to avoid welding/soldering oring connections to pipe.

I'll have to weigh the risk/benefit on this rear evap custom system which will have some tight bends and narrow cavities through which pipe or hoses will go through.

Thank you for the reply bohica2xo

Better leave yourself plenty of room to swing TWO wrenches wherever you leave a flare joint. Be prepared to apply 45 to 80 ft/lbs of torque to the fittings to meet spec.

Once you have 2 or more bends in a hard line it becomes really difficult to "thread" anywhere.

The minimum bend radius for 5/8" ID refrigeration hose is 3 inches. For standard J2064 type C barrier hose. .960 OD. Biggest hose you need.

Remember that you can buy 90 degree beadlock to beadlock fittings if you really need a tight bend.