1. That is a very cool idea! You would need a cap tube ID gauge of course. But then just unbraze the ends, get the length, and you can work out the capacity of common refrigerants. Somewhere I have an extensive chart showing all possible combinations but Supco probably has a conversion chart from non-Supco cap tubes to Supco cap tubes. I know some people dislike Supco but I have had good luck with their cap tubes and sizing.

PHM
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Originally Posted by mjohnson2981
If I change the compressor, can I determine the current size of compressor from length and diameter of the cap tube?

2. Originally Posted by mjohnson2981
If I change the compressor, can I determine the current size of compressor from length and diameter of the cap tube?
Given length, ID, pressure difference and the mixture going (R12 + xx % MO), it gives you the flow in grams/minutes. Since latent heat of R12 is well understood, you can calculate it.

In modern fridges, the high pressure supply/return going into box through a shell and tube type exchanger which uses the return gas/residual liquid to cool off the liquid refer. going into evaporator. This minimizes the liquid entering the comp. and it sends the sensible heat of liquid refer into the compressor, not the cooled space. This amount results in an error if omitted in calculation.

With fridges having 300-600 BTU, I'm not sure what the amount of error would be just by using the flow rate. This is something you might want to ask refrigeration eningeering forums. Its not something service techs deal with.

3. You can just put the cap tube inside the suction line to accomplish this,

PHM
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Originally Posted by ICanHas
. . . . In modern fridges, the high pressure supply/return going into box through a shell and tube type exchanger which uses the return gas/residual liquid to cool off the liquid refer. going into evaporator. This minimizes the liquid entering the comp. and it sends the sensible heat of liquid refer into the compressor, not the cooled space. This amount results in an error if omitted in calculation.

With fridges having 300-600 BTU, I'm not sure what the amount of error would be just by using the flow rate. This is something you might want to ask refrigeration eningeering forums. Its not something service techs deal with.

4. Originally Posted by Poodle Head Mikey
You can just put the cap tube inside the suction line to accomplish this
Which is exactly what I described.

TS: The name tag you took a picture of gives you more clue than you think.
It says 1/8 hp. So, the capacity range we've given so far is about right.

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