reducing iwaki pump inlet/outlet

[BillA]

NICE link pHaestus
almost a complete listing of things ignored in WCing

ahh Ben, so near and yet so far - eh ?

[Skulemate]

pHaestus

Thanks, but I really have no use for it anymore, as I've recently upgraded to a motherboard that has a diode reader (of sorts). I do appreciate your offer though (and your remembering ).

[Blackeagle]

How's it coming along?

[m3_arun]

if youre talking about the barbs.... i still have to make the trip to home depot to pick up those barbs. icouldn't find the right ones at McMaster.

im planning on 3/4FPTx5/8"barb.

the actual internal diameter of the inlet/outlet on the pump is exactly 1/2".

i dont really have resources/skill to make an inlet reservoir.

[Blackeagle]

I think what BillA was try'n to tell you is that the inlet, which has weak suction, benifits from larger lines as they offer less friction/resistence to the water. In other words have the water piled up on the inlet side waiting to get in. Which is exactly what a set up with a large 1 1/2" line (res) that reduces to 3/4" only at the last moment will give you. A 3/4" FNPT & 3/4" barb with a 3/4" line to minimumize resistences some would help out your pump and requires no modding/building skills. I'd use braided or copper line to insure no collapse or kink problems over time.

BigBen uses 3/4" lines on his Little Giant pump for best performance, and that pump isn't as powerfull as a MD30-rlz. Might want to PM BigBen and ask how much better his performance is with 3/4" vs. 5/8".

[Blackeagle]

I double checked McMaster and I made a mistake when I told you they were on the 1st page under barbed tube fittings.

They are in fact on the 3rd page of the barbed tube fittings area.

Sorry for the error.

[bigben2k]

Hardware stores don't usually carry those threaded barbs, in 1/8 increments, at least not in my area.

As for the McMaster part, it's# 5372K218 (nylon). (3/4 FNPT by 5/8 barb). They don't seem to have the brass equivalent.

I can't comment on 3/4 vs 5/8, but I can on 3/4 vs 1/2, to a certain extent: it depends on the flow you achieve. I was hoping to get to 4 gpm, but I was over-optimistic. At that flow rate, 3/4 ID tubing would have been a necessity, otherwise the tubing would be a significant restriction within the whole loop.

At 3 gpm, 1/2 tubing will have a pressure drop equivalent to 0.2 inches of head. 3/4 will drop 0.07 inch. This is all for 1 inch of length of tube (!).

At 2 gpm, 1/2 tubing will have a pressure drop equivalent to 0.1 inches of head. 3/4 will drop 0.01 inch.

At 1 gpm, 1/2 tubing will have a pressure drop equivalent to 0.03 inches of head. 3/4 will drop 0.004 inch.

These were calculated using the Hazen-Williams formulae, and as I found out recently, it may not be accurate at all.

:shrug:

[Skulemate]

Sure they carry them Ben (3/4" NPTF x 5/8" Hose in Brass). I just bought a package of those myself... the key is to look under "Pipe to Hose Adapter," not "Pipe to Tube Adapeter." The part number is: 91465K411.

[Blackeagle]

BigBen,

How high a flow did you get with the 3/4" lines? And what are the specs on your Little Giant?

Skulmate,

Thanks, I'd missed those.

[Skulemate]

No problem. As I said before, they match the ID of the connections on my 20-RZT pretty much perfectly, though that may not be the case for the 30-RZT.

[bigben2k]

Originally posted by Blackeagle
BigBen,

How high a flow did you get with the 3/4" lines? And what are the specs on your Little Giant?

Skulmate,

Thanks, I'd missed those.

I'm still working on the block, and I don't have a pressure drop calculation, yet... sorry.

[m3_arun]

ok. thanks for the part number.

they match the ID of the connections on my 20-RZT pretty much perfectly, though that may not be the case for the 30-RZT.

yah they match the ID of the 30rlzt too. im actually going to use 1/2" tubing, because, as bigben2k pointed out, the pressure drop is not so significant as compared with 3/4" tubing. cathar calculated the flow to be about 2.5gpm in my system.

[BillA]

you guys are fools

you thinking Iwaki put 3/4"NPT connections so you should run 1/2" lines ?

pHaestus wrote an article with an excellent link,
I put up some graphs, others have posted . . . .

"but a man hears what he wants to hear, and disregards the rest"

bah, pearls before swine

[bigben2k]

Bill's right.

What you really want to do, is use 3/4 tubing for the connection to the pump inlet. The rest of your tubing can be 1/2.

This is based on allowing the water to enter the pump unrestricted, at a lower velocity. The fitting alone is *apparently* not enough.:shrug:

[Skulemate]

Bill

Iwaki also makes a variation of the MD-20-RZT with 5/8" hose barbs rather than 3/4" NPT fittings... perhaps they are the fools? I am simply following the recommendation of their sales rep with my choice to go with 5/8" barbs and hose all around.

[BillA]

there are 2 somewhat different situations here (if I understand):

- a 20-RZT with 5/8" lines
- a 30-RZT with 1/2" lines

anything suggested there ?
one can drop the pump's head wherever desired,
but the only cooling to be derived from such is IN THE WB

now a 20-RZT in a WCing system is pretty extreme (though I consider it a 'good' choice)
while a 30-RZT is quite beyond any actual benefit, and will add a considerable heat load to the rad

but BOTH these pumps, and the consequent expense of same, would seem to justify (necessitate even ??) paying attention to ALL the details
- and OPTIMIZING everything possible
-> because if the flow rate is not 'reasonable', you're gonna be heating the water big time

there was a pretty good 20+ page thread on pump heating from a couple of years ago on the hard forums, but they wiped it out
- you might chew on this one. its related though actually about pressure
http://forum.oc-forums.com/vb/showth...hreadid=142006

just to repeat: any inlet restriction is unwise
with a high $ pump, its stupid

[m3_arun]

ok. i guess i'll go with a 3/4"FPTx3/4"barb for the inlet. the problem is i dont have a 5/8x5/8x3/4 Y piece... gonna have to find one of those.

[Blackeagle]

I found that thread that BillA mentioned. Go to the overclockers site and in their articles area under watercooling is a article called.

Water cooling flow rate and heat transfer

Only a one page article, but at the bottom it gives a link to the thread that BillA refered to above. Very good stuff, I spent close to 2 hours reading & rereading.

edit:

That link is to a thread at O/C forums, not [H], so I guess it isn't the one BillA mentioned, but sill a extreamly good read.

[m3_arun]

what do you think of running a full 3/4" system (except for the block). would that be good? would i still need to worry about inlet restriction? the only problem im facing in that case is the block, which has 1/2" fittings

[BillA]

if you get your lines too large you will not have enough velocity to clear them of air
5/8" is more than adaquate (and quite overkill for a 'normal' pump)

[m3_arun]

even for a md30rz?

[BillA]

5/8" will be fine

[m3_arun]

ok... so should i use 3/4" barbs with 5/8" tube? that would be better than 5/8" barbs right?

[BillA]

sure

[m3_arun]

do you know any place that sells a 5/8x5/8x3/4 y piece?