Anyone tried 5/8" (16mm) barbs?

Celoth · Oct 24, 2007

I found a local manufacturer that makes some 16mm hose barbs with both G1/4 and G3/8 thread, and I was wondering if those would be good with 1/2" ID ClearFlex tubing? Supposedly it's quite possible to fit the 1/2" ClearFlex on a 16mm barb by heating the tubing in boiling water first and it makes it a really tight fit once it cools, to better prevent leaking. The added ID of the 16mm barbs should help the flow too I'd think.

Unless it's been tried and tested and doesn't improve anything, I think I'll contact the manufacturer to get some info on their retailers.

meionm · Oct 24, 2007

I doubt using bigger barbs will help when tubing remains smaller size.

Automata · Oct 24, 2007

meionm said:
I doubt using bigger barbs will help when tubing remains smaller size.

Well, actually, it would decrease the resistance that other barbs make.

Think about it this way.

1/2 id tubing and a 1/2 od bard. They fit perfectly into each other. You lose the thickness of the barb (metal) x 2. So there is resistance at that barb.

Now if you increase it to 1/2 id tubing and 1/2 id barb you would theoretically have the same resistance as the tubing.

So it may, but I doubt the 1/2 od barbs restrict flow at all...

SolidxSnake · Oct 24, 2007

It will help the flow a bit (the ID of those barbs is probably closer to 1/2" than 1/2" OD barbs are). However, you're probably better off sticking with 7/16" over 1/2" OD barbs. 1/2" tubing provides plenty of flow (most of the time excessive amounts) for just about all standard loops. 3/8" ID tubing still has plenty of flow for most loops, but people stick with 1/2" anyway. It's a point of diminishing returns.

muddocktor · Oct 24, 2007

According to the sticky thread Cathar has right here, it isn't going to make much difference. He didn't test 1/2" ID tubing stretched over barbs the size you are talking about, but he did test 7/16 tubing stretched over 1/2" barbs and the difference between the 7/16 and 1/2 tubing over 1/2 barbs really wasn't enough to talk about, 0.1 C. And with you talking about 1/2" tubing and 5/8" barbs, the difference would be even less. You hit a point of diminishing returns that doesn't justify the expense and the hassle.

EDIT: Now if you want to do this for tighter connections, then it will do the trick. I just switched to 7/16" tubing over 1/2" barbs for that reason myself, plus the 7/16 is easier to route in my case. Just don't expect a noticeable increase in performance doing this.

meionm · Oct 24, 2007

thideras said:
Well, actually, it would decrease the resistance that other barbs make.

Think about it this way.

1/2 id tubing and a 1/2 od bard. They fit perfectly into each other. You lose the thickness of the barb (metal) x 2. So there is resistance at that barb.

Now if you increase it to 1/2 id tubing and 1/2 id barb you would theoretically have the same resistance as the tubing.

So it may, but I doubt the 1/2 od barbs restrict flow at all...

Fittings are still G1/4

I think I read this somewhere that there is no real benefit with tubing larger than 1/2id.

Celoth · Oct 25, 2007

It is actually partly for tighter connections that I am looking into it, but ID is certainly important too. I also found a 14mm barb with 3/8" thread, and both the 14mm and 16mm versions would be good for my two PA160s if I use the 1/2" tubing, but if I can't find anything decent for the waterblocks and pumps (ideally a high-flow 14mm x G/14) then I'll probably go down to 7/16" tubing instead.

Celoth · Oct 25, 2007

I think I am gonna order some of them. Next time I visit my cousin (a smith by trade) I'll have him help me drill them out in his workshop to increase the ID a little. I should be able to get 10mm ID on the G1/4 fittings, and 1/2" ID on the G3/8. I can probably modify the opening of the barb on the G1/4 to make a smoother transition from 1/2" to 10mm ID too.

I am sure some of you may be thinking it's overkill, but I am having a lot of fun with this, and I am waiting for the X48 or 780i chipset anyway, so I am in no rush at all. Besides, the more I optimize the flow, the quieter I can run the pump and silence is important to me. :bday:

voigts · Oct 25, 2007

I've used 5/8" barbs before on my reservoir and any other connections that I could. It does provide the smoothest possible transition at barb points, hence why 7/16"ID over 1/2" barbs is recommended. But as was mentioned, the difference is so small that it really doesn't make a difference. I now just use 1/2"ID tubing over 1/2" barbs as it is just easy to work with. I hate fighting to get tubing on and off, especially given that when I am usually working on my system, I am doing it out in a workshop where I don't have ready access to hot water. I also find it annoying to have to cut off every tube as when using 7/16"ID.

Celoth · Oct 25, 2007

voigts said:
I've used 5/8" barbs before on my reservoir and any other connections that I could. It does provide the smoothest possible transition at barb points, hence why 7/16"ID over 1/2" barbs is recommended. But as was mentioned, the difference is so small that it really doesn't make a difference. I now just use 1/2"ID tubing over 1/2" barbs as it is just easy to work with. I hate fighting to get tubing on and off, especially given that when I am usually working on my system, I am doing it out in a workshop where I don't have ready access to hot water. I also find it annoying to have to cut off every tube as when using 7/16"ID.

Yes good point about tubing being hard to get off again. That is the main drawback to it. It is my hope, however, that once it's all setup, I don't have to change the actual tubing for a long while. I have been thinking about how to add an easy way of draining the system and refilling again, without cutting anything, but haven't come up with anything that sounds really good yet.

Maybe 2 Ts in a row before the pump intake? The first one for outlet into bucket or sink (via attached extension hose) and the second one as a standard T-line (right before the pump) for intake from the faucet or container with distilled water. The pump will have to do the work flushing the system I suppose, while I pinch the tubing between the two Ts. Given proper pre-cleaning and a good anti-algae/corrosion additive, how often do I have to change the water?

Suggestions welcome.

voigts · Oct 25, 2007

Celoth said:
Yes good point about tubing being hard to get off again. That is the main drawback to it. It is my hope, however, that once it's all setup, I don't have to change the actual tubing for a long while. I have been thinking about how to add an easy way of draining the system and refilling again, without cutting anything, but haven't come up with anything that sounds really good yet.

Maybe 2 Ts in a row before the pump intake? The first one for outlet into bucket or sink (via attached extension hose) and the second one as a standard T-line (right before the pump) for intake from the faucet or container with distilled water. The pump will have to do the work flushing the system I suppose, while I pinch the tubing between the two Ts. Given proper pre-cleaning and a good anti-algae/corrosion additive, how often do I have to change the water?

Suggestions welcome.

I have used several different ways of making a drain using some kind of ball valve. I currently am using a simple 1/2"x3/8"x1/2" PEX T fitting (Lowes) at the lowest part of the loop with a vacuum line stop (auto parts store) clamped on. I just use a funnel with a piece of tubing attached and undo and remove the stop to drain into the funnel/tube. This is the most compact drain I have ever used, and it works fine. I then use a compressor to blow air into my fillport to get any undrained water out of the loop through the drain.

Some people go a year or more without changing fluid. I prefer to go no more than six months or so as antifreeze's PH buffers diminish over time.

Moto7451 · Oct 25, 2007

Sounds good to me. Considering we can't seem to get 1/2" G3/8" brabs from anyone else, I think it matters if it improves performance or not

. What material are they made out of?

Celoth · Oct 26, 2007

voigts said:
I have used several different ways of making a drain using some kind of ball valve. I currently am using a simple 1/2"x3/8"x1/2" PEX T fitting (Lowes) at the lowest part of the loop with a vacuum line stop (auto parts store) clamped on. I just use a funnel with a piece of tubing attached and undo and remove the stop to drain into the funnel/tube. This is the most compact drain I have ever used, and it works fine. I then use a compressor to blow air into my fillport to get any undrained water out of the loop through the drain.

Some people go a year or more without changing fluid. I prefer to go no more than six months or so as antifreeze's PH buffers diminish over time.

Ok good idea. Thanks much.

Don't have a compressor, but a modded bicycle pump could do the same trick I am thinking. It shouldn't take a ton of pressure to get all the liquid out I'd think. Not sure about the radiators though?

I'll start looking for a brass fitting like that (with hose barbs). There has to be one out there! So far only found em in plastic though.

Anyone tried 5/8" (16mm) barbs?

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