Suction line ID

sdumper · 10-22-2009, 11:30 AM

All, I want to try a steel braided flex line on a very expensive build I have planned for mid November. The suction line arrive today and its beautiful!!
60 inches of braided steel flex but its also 1/2 i.d. which is much larger than I have ever used before. Do I have anything to be cautious about? I don't see it being an issue but wanted to check around before I brazed anything...

Note the fitting will be reduced down and a stub brazed in so that its the same size as the one next to it.

sdumper · 10-22-2009, 08:49 PM

LoL bump...I thought this was going to be an easy question and someone would say its too big

[XC] gomeler · 10-22-2009, 09:14 PM

Nothing wrong with a large diameter suction line, only problem I foresee is finding the right pipe insulation/sleeving.

n00b 0f l337 · 10-22-2009, 09:24 PM

Working pressure goes down very fast, as does its ability to flex, with larger diameters.

wdrzal · 10-22-2009, 11:57 PM

The only problem with a way oversized suction line is it reduces suction gas velocity. Remember oil is in solution with the rerigerant in the liquid phase. In the vapor phase the oil drops out and is swept back to the compressor by the velocity of the vapor. 400fpm is a good ruleof thumb,but these small systems 200 to 400 fpm wil be fine

[XC] gomeler · 10-23-2009, 03:13 AM

Quote:

Originally Posted by wdrzal

The only problem with a way oversized suction line is it reduces suction gas velocity. Remember oil is in solution with the rerigerant in the liquid phase. In the vapor phase the oil drops out and is swept back to the compressor by the velocity of the vapor. 400fpm is a good ruleof thumb,but these small systems 200 to 400 fpm wil be fine

We're talking about the 2nd stage of a cascade though, so oil in the suction line should be minimal at worst and so viscous that regardless of what suction velocity you have the stuff is going to move like molasses. I imagine the only real oil movement you get is during the pulldown phase when the suctionline is warmed up.

ruffus · 10-23-2009, 03:15 AM

i think the only problem u will run in to is that it will not flex that well and if this is gas tight the stuff we use here in canada for our natural gass then its only been tested of 8 to 15 psi so i would do a good pressure test on it if that is what the stuff is

sdumper · 10-23-2009, 04:55 AM

3rd stage actually and using hopefully r14.

Unseen · 10-23-2009, 09:01 AM

Nice too see that you are not building only for yourself

In some cascades i made in the past i wanted to be sure that i wouldn't have problems in suctions. So i added an extra protection to the joints. Maybe you should consider sth like this.

Take a look at the pic and you'll see what i mean.

sdumper · 10-23-2009, 09:13 AM

Quote:

Originally Posted by Unseen

Nice too see that you are not building only for yourself

In some cascades i made in the past i wanted to be sure that i wouldn't have problems in suctions. So i added an extra protection to the joints. Maybe you should consider sth like this.

Take a look at the pic and you'll see what i mean.

Very nice!!!

Thanks for the tip

By the way that unit in the picture looks really nice...

tanguintel · 10-25-2009, 10:10 AM

perfect clean