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View Full Version : Oil return on a two stage / A few questions on solder.



gkiing
03-17-2005, 08:58 PM
I've proceeded to begin my two stage co2 cascade, I'm going to be using a 1/4hp tecumseh compressor for the low stage, and have already made an oil separator very similar to the one pc ice outlined in his three stage thread (I used 1 & 1/8" pipe x 12" with copper wool inside). I was originally planning to use captube + a packless valve to return the oil since I dont have a proper oil float, but since the valve costs $40 I was hoping to use captube only.

What length of captube do I need for oil return? I dont know the quantity of oil in the compressor but I can measure it if needed.

One more question; I've been using stay-brite 8 solder quite a bit lately as I've found that it doesnt char the pipes black with oxidization. It's pretty expensive for the quantity, would it be safe to use it on only the high stress joints and use 60/40 or 50/50 tin/lead solder on the other (non vibration stressed) joints? I braze most of my joints with 15% silfoss but there are occasions when the heat isint't appealing to the surrounding area and surfaces.

gkiing
03-18-2005, 09:29 AM
cmon.. somone must know? Pcice, chilly1 ??

wdrzal
03-18-2005, 10:03 AM
The answer on your solder question is NO, lead based solder(soft) is reactive with refrigerants,it will break down and leak in time, walt

while I see act/oxy torches are not used by most here,they should be, they have the capability of bring the joint up to temp faster than other torches. This minamizes the amount of heat transfered down the tube. The longer it takes a joint to be brought up to brazing temp,the more heat will be conducted away.

cap tube ? just remember how important oil return is in low temp systems,

ps I did like your neat piping work on your other rig :toast:

Stewie007
03-18-2005, 10:34 AM
Low temp solder is too brittle for this type of joint. It'll crack before it breaks down. For refrigeration systems you MUST use high temp alloys. If you don't want the inside of your system being dirty then get a cylinder of nitrogen, and nitro purge while you braze. Release the nitrogen into your system before you braze, and let it run for 5-7 minutes. You want to make sure you have an open valve so that the nitrogen doesn't prevent you from brazing you last joint.

If you do it right, the inside of your system will be squeaky clean. Use a wire brush to clean the outside.