Since most waterblocks have a 1/4 thread, why use a 1/2 hose?! less kink?

[hokiealumnus]

Martin thinks (and it stands to reason) it has to do with the 90° bend on the inlet. Most (all?) aftermarket tops have inlets up top that eliminate the bend.

 

[ntino]

Martin thinks (and it stands to reason) it has to do with the 90° bend on the inlet. Most (all?) aftermarket tops have inlets up top that eliminate the bend.

Oh. I didnt look at the pump design, but now i see it... of course it would be because of the pump - there is not one decent pump out there that would have a bend right after, this restricts flow out of the pump - of course they did it to save space, but they should have done a smoother transition which would mean a slightly bigger top though.

 

[Mark620]

Some things to consider:
1. NPT Pipe thread size is not related to pipe ID diameter.
...A 1/4" NPT pipe thread uses nearly a 3/4" drill drill bit. This is ID .vs. OD

2. If you double the diameter of a pipe you increase its volume by 4X.

The water block(s) have a lot more resistance to flow than any other
component in the system.

When you have a restriction : at the point of restriction(Vena Contracta)
you have a pressure loss(pressure drop) at some point after the restriction
point you have a pressure recovery but it is never 100% and you have a
flow loss that does not recover.

 

[thorilan]

but that one small diameter puts alot of resistance on the whole loop -

it still stands. you have used a lot of adjectives that don't fit

in one of your other posts you use the word tremendously.

what im getting at is the original poster is looking for some information. If what you just said in quotes was true then there would be almost no flow due to the cumulative properties of resistance .

 

[ntino]

Some things to consider:
1. NPT Pipe thread size is not related to pipe ID diameter.
...A 1/4" NPT pipe thread uses nearly a 3/4" drill drill bit. This is ID .vs. OD

2. If you double the diameter of a pipe you increase its volume by 4X.

The water block(s) have a lot more resistance to flow than any other
component in the system.

When you have a restriction : at the point of restriction(Vena Contracta)
you have a pressure loss(pressure drop) at some point after the restriction
point you have a pressure recovery but it is never 100% and you have a
flow loss that does not recover.

this is all true except that the NPT size IS usually related to pipe ID, atleast when it comes to schd 40 pipes, and most others - a 1" npt thread is going to have an inside diameter of a 1" schd 40 pipe - which is around 1"

The pressure actually does not change in the system prior to the point of restriction, because water does not compress much, atleast in our systems. There is practically no recovery after a restriction, unless you have volume that can offer an inductor effect - in which case the higher velocity of water coming out is going to attract more water with it, but you would need an injector.

but my main point stands correct - the most restriction comes from the components themselves, not the pipes

 

[QuietIce]

If you would like information on tubing sizes and how they impact the water loops we use I suggest the following from Cathar:

http://www.overclockers.com/forums/showthread.php?t=515368

 

[ntino]

it still stands. you have used a lot of adjectives that don't fit

in one of your other posts you use the word tremendously.

what im getting at is the original poster is looking for some information. If what you just said in quotes was true then there would be almost no flow due to the cumulative properties of resistance .

What we are arguing about is the fact that you think resistance accumulates, whereas I am saying that resistance is mostly caused by the single thing in the system that resists the most(provided its a closed loop with all components inline).
So as an example closer to the world of liquid cooling - if you have a water block that provides x resistance at 100gph it matters not that your tubes are oversized and provide 25% of that resistance - almost all of the resistance is going to be caused by the component with the most resistance.

BTW, I am the original poster and I wasnt clear on why people were using 1/2ID tubes with 1/4g thread (I was assuming that ID of it is 1/4 as it would be with regular plumbing fittings e.i. plastic copper or pex pipes)

Thanks for clearing up the G 1/4 sizing for me.

 

[QuietIce]

The 'G' is a BSPP spec, British Standard Pipe Parallel (parallel threads instead of tapered), and can be found under ISO 228 ...

 

[thorilan]

So as an example closer to the world of liquid cooling - if you have a water block that provides x resistance at 100gph it matters not that your tubes are oversized and provide 25% of that resistance - almost all of the resistance is going to be caused by the component with the most resistance.

and im saying this is misleading and in some situations completely in correct.
otherwise we would care more about component order and less about getting our tubing runs shorter. while i understand the idea you are thinking , its not nearly in the proportions you are estimating.

 

[thorilan]

btw i said cumulative not accumulates . completely different meanings . the intent of accumulates gives the idea of resistance building in one general area compared to cumulative meaning PURELY just the addition of the item as a whole sum or total not with the intent of where the resistance is because its in the whole loop.

 

[Mark620]

this is all true except that the NPT size IS usually related to pipe ID, atleast when it comes to schd 40 pipes, and most others - a 1" npt thread is going to have an inside diameter of a 1" schd 40 pipe - which is around 1"

Your right - I was not clear...

There is a good fit (meaning the ID is close to the same)
between 1/4" Sch 40 pipe and 3/8" OD x .035 wall tube
You can get this in plastic and metal.
I use 304SS tube at work - this would look great (imho).

As long as your tube has the same or larger ID as the fittings on the
pump, rad, your pressure drop (loss) will be minimal.

The 'G' is a BSPP spec, British Standard Pipe Parallel (parallel threads instead of tapered), and can be found under ISO 228 ...

and British Taper threads, BSPT (British Standard Pipe Taper Thread)
The 1/4" BSPT is remarkably close to 1/4" NPT too.

 

[Mark620]

What we are arguing about is the fact that you think resistance accumulates, whereas I am saying that resistance is mostly caused by the single thing in the system that resists the most(provided its a closed loop with all components inline).
So as an example closer to the world of liquid cooling - if you have a water block that provides x resistance at 100gph it matters not that your tubes are oversized and provide 25% of that resistance - almost all of the resistance is going to be caused by the component with the most resistance.

The tubing itself will provide very little resistance.
Elbow fittings provide a significant resistance when compared to a straight fitting.
Every time you change direction drastically you will get a pressure drop.

BTW, I am the original poster and I wasnt clear on why people were using 1/2ID tubes with 1/4g thread (I was assuming that ID of it is 1/4 as it would be with regular plumbing fittings e.i. plastic copper or pex pipes)

I think you are correct on this if they are using 1/4" sch 40 pipe fittings.
But you can get thinner walled fittings that would have larger ID than a std fitting.

 

[QuietIce]

and British Taper threads, BSPT (British Standard Pipe Taper Thread)
The 1/4" BSPT is remarkably close to 1/4" NPT too.

http://www.engineeringtoolbox.com/british-pipe-threads-d_754.html

Parallel (straight) Threads
BS parallel threads are also referred to as British Gas, British Pipe Parallel or Parallel Fastening Thread.

Common symbols used for the thread: BSP, BSPP, BSSPI, BSPF, BSPG, PS, Rp, G

The BSPP (parallel) male will mate with a BSPP (parallel) female or a female port.

Usually marked: G size ISO

Taper Threads
BS taper threads are also referred to as British Standard Taper Pipe, Pipe Taper or Conical Thread.

Common symbols used for the thread: BSPT, BSPTr, PT, KR, R, Rc

Usually marked: Rc size ISO

Characteristics of BSPT taper threads:

Sorry, I didn't see a 'G' standard under tapered thread and (I guess incorrectly) assumed it was strictly a BSPP standard. Maybe these guys need to update their webpage.

Edit
I see what you're saying. The chart on that page applies to both BSPP and BSPT - gotcha' ...