7/16" ID (5/8" OD) tubing - ultimate tubing size cross-over?

I have been investigating the use of 7/16" ID (5/8" OD) Tygon R-3603 tubing as a cross-over between 3/8" and 1/2" ID.

In terms of pressure-drop vs length, 3/8" tubing becomes significantly restrictive for the sorts of pumps that we use when targetting above 5LPM flow rates. If you don't really expect to be seeing much above 5LPM flow rates (due to the pump's characteristics coupled with the blocks/radiators in the system), then 3/8" ID tubing is just fine to use, and the performance difference between 3/8" ID and something larger would really be quite negligable.

For the higher flow blocks that really like >5LPM flow rates to strut their stuff, something bigger than 3/8" ID pretty much becomes a necessity (unless you grab a high pressure pump but then you're just fighting the problem with brute force).

The most commonly available choice is 1/2" ID. 1/2" tubing is great for high flow applications, but it is as we know rather large and heavy, and somewhat difficult to turn corners unless it has a fairly thick walls, also making it even larger and heavier. Basically the most useful 1/2" ID tubing is with 1/8" walls making for a 3/4" OD, or something that's pretty bulky. A 1/2" ID tubing setup is good for around 13LPM or so flow-rates before thinking about needing to go to something even bigger. 13LPM though is ~3.5GPM and no one will be seeing flow rates even remotely that high with today's modern moderate-high restriction blocks.

So there has to be a middle ground, and 7/16" happens to be it, and using it by stretching it over 1/2" OD barbs. This creates a nice interface between the ID of the tubing and the ID of the barbs, with there being less of a transitional ID change than what occurs with 1/2" ID tubing over 1/2" OD barbs. What this means is that at the barbs there is actually less pressure drop occurring as the water is pushed through the barb's opening with 7/16" ID tubing than there is with 1/2" ID tubing. So while the slightly smaller ID of the 7/16" ID tubing makes it more restrictive than 1/2" ID tubing, much of this loss is made up by gaining at the tubing/barb interfaces. I calculated that in a system with 1/2" OD barbs and 7' of tubing that using 7/16" ID tubing offers about the same level of pressure-drop as would using 1/2" ID tubing. For much larger tubing lengths (>10') then the game is clearly won by 1/2" ID tubing. For <5' total tubing lengths 7/16" ID tubing wins out fairly easily. For anything up to 10LPM, 7/16" ID tubing is perfectly adequate before possibly thinking about going to 1/2" ID tubing. That's around 2.7gpm, which is still way higher than the flow rates you'll ever see in a real-world system with modern blocks.

Being of a smaller ID, we can get away with using a smaller wall thickness, and instead of using 1/8" wall thickness like we need on 1/2" ID, it is possible to use 3/32" wall thickness with the 7/16" ID tubing (total of 5/8" OD) with just as much flexibility, but with a whole lot less weight and bulk.

I will be redoing my systems in 7/16" ID (5/8" OD) Tygon R-3603 as soon as I find the time to order some in.

Incidentally, managed to track down a site that sells what I'm talking about in 50' rolls:

http://www.mgscientific.com/pricequote/group.asp?GROUP_ID=8510

Specifically item code T600-26, which works out to around $2.50 per foot.

interesting, so in a 1/2 system with just a couple feet of hose you might actually benefit from using 7/16?
hmmm, i just might have to try that stuff out if i can find it at a place that sells it by the foot.
or did that whole post go right over my head

~Magick_Man~

Sounds like group buy time? I'd chip in for 20 bucks worth.

Hmm, so is 7/16 much easier to bend than 1/2? If its better to have the 7/16 in a short loop, i may try it when i rebuild my system in a few weeks, assuming i can find that stuff.

7/16" tubing is probably a happy medium for the extreme people, actually probably as much as even needed as 1/2" ID tubing is almost always overkill.(mostly always)

I thought about this a while back but I havent ever done it.

Jon

mcmaster has the size in the Masterkleer tubing: product 5233K44
25 feet minimum, $0.36/foot

www.mcmaster.com

gungeek said:

mcmaster has the size in the Masterkleer tubing: product 5233K44
25 feet minimum, $0.36/foot

www.mcmaster.com

Click to expand...

I actually just grabbed some of that to try it out . I've always favored Masterkleer over Clearflex..... I believe they have similar specs but Clearflex gets foggy fast, M.K. keeps its transparency very well. The bend radius on 7/16" is noticebly better. I guess the real test is the wall strength and how it withstands against collapsing.

MasterKleer 7/16" and 1/2"

any updates on this or is anyone else using this? I'm thinking about getting some for my new project.

You might want to ask in this thread http://www.ocforums.com/showthread.php?t=331537&page=2&pp=30&

I'm curious as to what their impressions are of the stuff too.

Well I needed to order other stuff from McMaster, every other day I seem to find something else I can order from them. McMaster lists the Masterkleer 7/16"ID 5/8"OD tubing as having a bend radius of 1 3/4", which is actually the same radius listed for the 1/2"ID 3/4"OD tubing. I might grab some of both, but it might pose a problem since I have several copper fittings that have ~3/4"OD's (the expanded fitting end). In my case I don't think I'd be as good as an alternative to others, since all tight bends will be aleviated with other methods.

A bit off topic, but which 1/2"ID 3/4"OD Tygon product from McMaster is the same stuff they sell at DangerDen? The most similar Tygon tubing I can find are the [clear] Tygon beverage&dairy tubing for $0.65 per foot with a bend radius of 3 3/4", and the [semi-clear translucent white] Tygon High-Flex PVC tubing for $1.36 per foot with a bend radius of 1 3/4"; the problem is that its not actually labled Tygon (comes up in the useless search function)... Otherwise the other stuff is WAY more expensive than the DD prices. I may as well get the masterkleer just because the McMaster catalog is so f-ing hard to figure out. You almost have to disect the pages and get into the mind of the writer - tygon pages include non-tygon where ever they can It'd be sooo much easier if they simply converted the web-based catalog to a web-based store and stop with the quasi-pdf'ish java [apparently?] catalog pages.

Jeez, the mcmaster sure doesn't like firefox. I hate having to switch to IE just to find things at their site.

Anyways, search this number 5554K19 @McMaster and you'll get the right tygon tubing. However, it's cheaper to buy from dangerden if you're gonna get the tygon. If you want 1/2"ID 3/4"OD clearflex 60 that's this # 5554K19.

One quick question about the various tubings...

I am currently using the Clearflex60 1/2x34 but have ordered the Masterkleer 1/2x3/4 due to the rapid fogging of the Clearflex which many have posted about.

My question is this....why are people so concerned with the ID of the tubing when the restriction points of the system are actually the 1/2 OD fittings? Maybe I am missing something here about the fluid dynamics involved but...assuming you have a fairly standard system then the loop passes through (assuming a reservoir is used) 8 fittings generally with a 3/8IDx1/2OD measurement- 2 fittings for the waterblock, 2 fittings for the pump, 2 fittings for the reservoir, 2 fittings for the radiator. Are most people using the 5/8 inch fittings with a 1/16 wall to get a true 1/2 ID? If that is the case in order to maintain the 1/2 integrity through the loop then will using a 7/16 ID tubing be much harder to fit over those 5/8 OD fittings?

Not being arguementative, just fairly new to w/c'ing and it hasnt made sense to me. Most w/c'ing sites offer the 1/2 ID tubing as a match for components with fittings that have a 3/8 ID. Arent the fittings the true limit on the system whether you use a 1/2 or 5/8 ID tubing?

the fittings/blocks are the limit, so downsizing tubing makes little to no difference, partially offset by the lessened turbulence at the tube to fitting junction

SnowRider said:

Jeez, the mcmaster sure doesn't like firefox. I hate having to switch to IE just to find things at their site.

Anyways, search this number 5554K19 @mcmaster and you'll get the right tygon tubing. However, it's cheaper to buy from dangerden if you're gonna get the tygon. If you want 1/2"ID 3/4"OD clearflex 60 that's this # 5554K19.

Click to expand...

I hadn't noticed this. What exactly happens? I have no problems with McMaster's site.

Well it mainly doesn't like it when I search for something. For example...... search "tygon" in the sidebar on the left in firefox (I'm using version 1.0pr) and click any of the results, well for some strange reason the "tygon hose" category works fine so don't click that one lol. But any other one of the results will open up in the sidebar for me instead of the main window. So it's really a hassle to find things in their site using firefox so I usually switch over to IE to do it. You don't have this problem? Try doing what I said and tell me if it happens to you. I'm curious now.

*Edit* - Okay, I just tried searching a few other random things on their site and all those results work perfectly fine hahaha. They all open in the main window but I guess tygon is the only thing that doesn't work right (for me at least). Strange

I'll change my w/c rig over to this per your advice when I get the chance to redo tubing/fluids and spin my radiator around 180º to prevent the tubes from kinking at the back. We'll see, the prestone antifreeze clouded up my tubing pretty bad.

SnowRider said:

Jeez, the mcmaster sure doesn't like firefox. I hate having to switch to IE just to find things at their site.

Anyways, search this number 5554K19 @mcmaster and you'll get the right tygon tubing. However, it's cheaper to buy from dangerden if you're gonna get the tygon. If you want 1/2"ID 3/4"OD clearflex 60 that's this # 5554K19.

Click to expand...

there must be something wrong with your browser, firefox works fine on the mcmaster site.

Bugsmasher said:

If that is the case in order to maintain the 1/2 integrity through the loop then will using a 7/16 ID tubing be much harder to fit over those 5/8 OD fittings?

Arent the fittings the true limit on the system whether you use a 1/2 or 5/8 ID tubing?

Click to expand...

no and no. you've forgotten, this is rubber tubing, meaning it stretches. most people say that the 7/16 is easy to stretch over the 1/2 fittings. seeing as how the tubbing is only 2/16 smaller than the 5/8 fitting size this seems reasonable, hence a tighter fit and improving flow speed a bit. i would suggest 7/16 tubung with 1/2 fittings so there isn't too much size difference.

if anyone can find 7/16 ID and 1/8 OD tubing please let me know. the 7/16 tubing on mcmasters site has 5/8 thick walls. that's waaaaaay too big.

edit: nevermind, i miss read the specs. 5/8 was the OD and the wall thickness is 3/32.