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3/8 tubing and fittings verses 1/2

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gigabit

Member
Joined
Feb 28, 2004
Location
Claymont Delaware 19703
How much performancce will i lose by using 3/8 tubing compared to 1/2.1 of the 3 reasons i wanna do this is my pc is loud man.When i have to turn up the polo 735's fan man it sounds like a hairdrier So reason #1 quiet down my pc.2# temps will not increase as much with %100 loads 3#It looks cool.Ok so im gonna run the pumps and rad and all in a old E machince case and out to my case.And i dont want those big fat ugly 1/2 tubes running all over.I think the 3/8 lines look much better.So am i gonna lose at lot with the 3/8.I was also thinking of making a chiller to go with this setup out of a widow A/C unit( i have 3 5000btu units that work but we dont use). Its not as good as a vaporchill or something but you can get 0c or better but you need to insulate the cpu/ tubes/ and mobo for any condensation.All i need for this is a good tank to hold the mix and insulate it and a good pump and some extra long tubing.But still 3/8 tubing and fittings is this gonna hinder this?
 
Well, the amount of flow needed does depend on your components...

This understood the cross section of the flow area of a 3/8" ID tubing is around 0.11 square inches while for the 1/2" ID tubing is around 0.20 square inches. In short the 1/2" tubing has nearly twice the flow area cross section of the 3/8".

Now take it a step further. Assuming you are using standard fittings then you will lose even more flow area. A standard 3/8" OD fitting has an ID of 1/4" while the standard 1/2" tubing fitting has an ID of 3/8". If you use these measurements as the most restrictive value in your system then your cross sections are as follows: 0.05 square inches for the 3/8" OD fitting and 0.11 square inches for the 1/2" OD fitting. That means that the flow area of the standard fittings for 3/8" is less than half the area of the standard 1/2" OD fittings.

In short if you need flow the 3/8" tubing will definitely restrict your system. There is a way to avoid this however. Use 3/8" ID fittings (make sure to get the thin walled ones) and put up with the hassle of getting 3/8" OD tubing over 3/8" ID fittings via heating the tubing so it can stretch. This approach will also lessen the turbulence which negatively affects flow as well. The downside is the need to be extremely careful not to overtighten clamps on the already stressed tubing to avoid cutting it.

If you already have 3/8" fittings on your components then the size of the tubing really has little effect other than to minimize the effect of turbulence. Remember its not the tubing that restricts the system normally. Its the fittings that fit inside the tubing ends that restricts the flow. Using 1/2" tubing basically normally means that you end up with a 3/8" flow cross section due to the fittings on the pump, blocks, radiator, etc unless you use the 'heat and stretch' means for stretching the tubing over larger sized fittings.
 
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Thanks
Bugsmasher
LOL I should have said fittings also.But thanks for the info .I have heard that i can use 3/8 tubing on 1/2 fittings.I just dont want those fat hose's running all over the place.But i guess i will go with the 1/2 tube tubing.Just wish it wasnt so thick.
 
Its definitely possible, its simply a challenge to stretch the tubing that much. Softer tubing like the Tygon seems to work a bit better than the stiffer tubing like the Clearflex 60.

The thinner walled tubing may be easier to get over larger fittings as well and will end up having a smaller overall OD. I think someone may have posted about using the 7/16" OD-1/2" ID tubing and they seemed extremely satisfied with it. I would watch for kinking but outside of that it may be a solution that will work for you. If you use the 1/16" wall fittings and want the 3/8" ID on the tubing it will only be 1/2" OD tubing and the chances are you could slip it over 1/2" OD fittings. Worth picking up a single fitting and a foot of tubing at a local store to give it a whirl at least ;)
 
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