Cap tube sizing rule

[Gary Lloyd]

I would like to propose a rule for sizing cap tubes (single stage systems). Based on what I have been seeing in the forums, I would propose the following:

For R404A/R507:

Using a center point of 150 watts load I would guestimate 10 feet (3 M) of .028 inch (.7 mm) cap tube.

For each increase of 15 watts, I would shorten the cap tube by 1 foot (30 cm).

For each decrease of 15 watts, I would lengthen the cap tube by 1 foot (30 cm).

Then for R22/R290 (propane) shorten 1 foot (30 cm).

For .026 cap tube, multiply by .7.

For .031 cap tube, multiply by 1.6.

It is best to stay between 5 feet (1.5 M) and 16 feet (5 M), with center range of 10 feet (3 M) being ideal.

Does this sound about right?

[Epsilon]

MOOOOODDDDD ?!?!?!

Please make this one a sticky

[DaBit]

Hoho, let Bowman and the others say that the old man is right

[Epsilon]

Yeah well

Whether or not it is true, the correct "rules" will be posted in this topic anyway. So a sticky wouldn't hurt


btw, just mounted my 172w pelt on a GF2 dangerden block. Home made coldplate and insulation ofcourse. Pics will be online soon (as soon i can get some1 to take pics :P)

[Ragnarok]

Does anyone know the exact length of the Mach I and Mach II capillary tube length?

[Weapon]

this definitely needs to become a sticky -- right now you have to dig thru a ton of threads to find the info on cap tube sizing for different refrigerants and different cap tubes.

on the one for R22, I think that is damn close to being right - I am still tweaking my latest R22 .028 direct die system but those numbers are looking pretty close to what I expect to end up using for it...

great thread gary

[Freezer]

Yeah great topic to pick up Garry!
It's always a very welcomed issue I believe. Would be nice to just use your rules to adjust captube length without having to annoy others for their help!

[Zejtan]

Wise words from a wise man.
But i still want my expansion-valve. ( THX ?? )

[chilly1]

Originally posted by Gary Lloyd
I would like to propose a rule for sizing cap tubes (single stage systems). Based on what I have been seeing in the forums, I would propose the following:

For R404A/R507:

Using a center point of 150 watts load I would guestimate 10 feet (3 M) of .028 inch (.7 mm) cap tube.

For each increase of 15 watts, I would shorten the cap tube by 1 foot (30 cm).

For each decrease of 15 watts, I would lengthen the cap tube by 1 foot (30 cm).

Then for R22/R290 (propane) shorten 1 foot (30 cm).

For .026 cap tube, multiply by .7.


For .031 cap tube, multiply by 1.6.

It is best to stay between 5 feet (1.5 M) and 16 feet (5 M), with center range of 10 feet (3 M) being ideal.

Does this sound about right?

Simply stated this is true...

[Marci]

Handy as all my parts arrived today... at LAST i can get this MkII over to 404!!

[FOO]

Gary, is there a standard (or somethin close to it) for r-12?

[Gary Lloyd]

For R12, I would shorten by about 3 feet.

For R134a, I would shorten by about 4 feet.

Keep in mind that all of these are educated guestimates, based on numbers and performance seen in these forums, along with interpolations of several online charts. I think they are pretty close.

[FOO]

ok so on a single stage, single evap on r-12 using .028 i would start @7 feet? i know this is just a guestimate and just want to make sure im reading it right. thanks

[Gary Lloyd]

How many watts heat load?

[FOO]

heat load should be 95-100 watts. gonna keep it conservative

[Gary Lloyd]

Starting with 7 feet for a 150 watt load, we add 1 foot for each decrease of 15 watts. We end up with 10 feet of .028 for a 105 watt heat load.

Actually I'm being conservative with this. You could probably add another foot, this being R12.

[FOO]

thatll work great, thanks again

[Weapon]

any guess for 66% R-134a, 22% R-22, 12% R-290??

hehe...found it on the charge plate for the high stage of a cryofreezer cascade system.

[Gary Lloyd]

I wonder if they are autocascading. That's not even close to an azeotropic blend.

[chilly1]

I bet that blend lands right around R500 about 5 deg colder than R12

[Weapon]

Originally posted by chilly1
I bet that blend lands right around R500 about 5 deg colder than R12

hmmm....it would be one helluva lot cheaper than R500. R500 is about $480 for a 30lbs cylinder from the webpricing I have seen.
might have to try that mix.

[Mr Dead]

Ok just to confirm before I put it all together,

According to Sisoft sandra my cpu is putting out 178W (2.5 barton mobile 12 X 218 at 2.15 Vcore)

I am going to use propane or if possible Propylene with 0.31 cap tube.

So I get about 11.5 feet of .031 cap according to Gary Lloyd figures.

sound about right?

[bowman1964]

Originally posted by DaBit
Hoho, let Bowman and the others say that the old man is right

well it is close enough....for goverment work i would say...



but there is no excate lenght....you see i get tons of pms on this ...and i tell everyone tha same thing....i can get you close..but you will have to fine tune and adjust to get the best temps at load....there are tons of varables..that cannt be figured...fine tuning is the only way.but problem today is people either can not or will not take time to fine tune.

garys formula is the best way i have seen to explain how to get close.

[paul007]

so 6ft of .28 would be what ya want for a 200w+ heatload hu??

[Gary Lloyd]

garys formula is the best way i have seen to explain how to get close.

See... The old man isn't as dumb as he looks. (Actually, nobody is.)

so 6ft of .28 would be what ya want for a 200w+ heatload hu??

That's .028, not .28, and it depends on what refrigerant we are talking about.