Piping layout question

[nike123]

I have recently started to commissioning some refrigeration equipment (mainly flake ice makers, ice water and and coolers for fishing boats) and contractor, I work for, telling me that I should make pipe arrangement as at #1 at following picture.




My current practice was #2 when there is no pump down or #3 when there is pump down. Both cases are when condenser (and compressor) are below evaporator.

It is interesting that is said to me that #1 is for R404A refrigerant and that blind pipe piece after T must bee 10" (25 cm) long. Also there is no need for oil trap in this case.
Since I cannot find any reference at that pipe arrangement in any literature, could someone comment on theory behind this and is this good practice and/or to point me to literature where this case is explained?

[chemi-cool]

#2 and #3 are obvious to me.

#1 is something new, interesting idea. I'm sure that there is some logic behind it.
Maybe Us iceman or Gary will shed some light on it.

[nike123]

#2 and #3 are obvious to me.

#1 is something new, interesting idea. I'm sure that there is some logic behind it.
Maybe Us iceman or Gary will shed some light on it.

Yes, it is new. They said that some Italian engineer has advised that to them few years ago, and they, since then, always fit pipes in that manner. I am not sure if the same case is even with pump down.
They said also that oil return problem is not existent since introduction of that piping practice.
It is pointed to me that for R404A is very important that blind pipe is very close to 10".

[michaelm]

They said also that oil return problem is not existent since introduction of that piping practice.
It is pointed to me that for R404A is very important that blind pipe is very close to 10".[/quote]

B”Hfficeffice" />>>

Do you mean that was a problem with oil return with P-trap enragement and by switching to the new arrangement the problem disappeared? >>

[Magoo]

Hi Nike123,
I haven't heard about this new concept either.
But thinking about it, with 404A system with good oil separation that the system will be oil free, and with out pumpdown, liquid carry from evaps will be assisted by traps, but with dead end extention would stop carryover to compressor and effectively store and allow to boil off at evaporator.
I would be inclined to fit a schrader on bottom of extension for future oil draining if necessary.
I could be completely wrong though.
magoo

[nike123]

Do you mean that was a problem with oil return with P-trap enragement and by switching to the new arrangement the problem disappeared?

n Yes. That is also how I understood them.

[Eeram]

No.1 looks like somebody could not decide where to go from there. Have never seen something like this.

[D.D.KORANNE]

#1 arrangement will need the verticle pipe entering horizontal pipe carry upto the bottom ( 1 or 2 mm ) above of the horizontal suction pipe. Besides, the verticle pipe will need a 45 degrees cut . the cut section of pipe will face the gas flow out of evaporator ; which will pick up any residual oil if any alongwith refrigerant.

[nike123]

#1 arrangement will need the verticle pipe entering horizontal pipe carry upto the bottom ( 1 or 2 mm ) above of the horizontal suction pipe. Besides, the verticle pipe will need a 45 degrees cut . the cut section of pipe will face the gas flow out of evaporator ; which will pick up any residual oil if any alongwith refrigerant.

It seems that you are familiar with that arrangement. Do you maybe have any reference in book or some article about that?