What fittings/adapters to use with a 3/4" NPT pump?

I now have an Iwaki MD20-RZT which has an 3/4" outlet an inlet and I need to convert this to 1/2" because I am using 1/2" ID tubing. I know that several other people in this forum have the pump I am using so I am hoping that someone will tell me how to connect 1/2" ID tubing to this pump.

I have been looking for 3/4" female NPT to 1/2" hose barb type adapters (because the pump has 3/4" male NPT inlet and outlet) but I have not been able to find any yet.

Any ideas?

Will this work for me?

http://www.thevalveshop.com/menu/manual/kerick/kericktf.html

Watts Brass Fitting, Part No. A-684
3/4" Threaded Female Hose x 1/2" Hose Barb Adapter.

Another thing is that I realized the inlet and outlet on the Iwaki are MPT and not NPT. What's the difference?

I measured the inner and outer diameter of the inlet and outlet and they actually turned out to be 1" OD and 1/2 ID". Now, I am confused.

mpt = male pipe thread ftp = female pipe thread both are NPT = national pipe thread hope this clears up things a bit I also have one of those Iwaki rlzt 20 pumps just need to get the rest of the stuff to get my water system up and as far as the I/D o/d on pipe threads heres a link that may help you make some sence out of the sizes of pipe thread ratings http://www.ajfittings.com/performance_charts.htm

You'll hobble that pump with 1/2" fitting (that's barely more than 3/8" ID) on the suction side. Connect a small res w/ 3/4" coupling (or make an oversized T connector out of PVC parts) and provide it all the water it needs on its intake for optimum performance. You're trying to use a thoroughbred to pull an applecart

Best bet is to go with 5/8" barbs that way you get the 1/2"ID. However if you really wanted to you could use 3/4"barbs cause 1/2"ID tubing will stretch or both of those.

USPLastics.com has the 1/2 - 3/4 reducer for 25 cents....might wanna consider them before paying more elsewhere...

_Siph

learning curve said:

mpt = male pipe thread ftp = female pipe thread both are NPT = national pipe thread hope this clears up things a bit I also have one of those Iwaki rlzt 20 pumps just need to get the rest of the stuff to get my water system up and as far as the I/D o/d on pipe threads heres a link that may help you make some sence out of the sizes of pipe thread ratings http://www.ajfittings.com/performance_charts.htm

Click to expand...

Thanks! That article helped a lot. I didn't really know squat about fitting types and sizes before I bought this pump. I am pretty much used to having 1/2" ID fittings on everything I buy so this pump and my new rads are the only things that are 3/4" right now (the rads are 3/4'' ID and 5/8'' OD).

Well, having just said that, now that I am thinking that I don't have to use any adapters. I was thinking about replacing the barbs on these heatercores (2 Balkamp 6603112s) with 1/2" fittings as well but if I am going to hook up the pump to the rads, then why the heck bother with reducing the hose size for both since they should be compatible, no? I mean I can just cut the tubes on those rads to make them shorter (and that is not really necessary either, I am going to do that for space reasons) and then slip some 3/4" tubing on the rads and the pump. The rest of the system is still going to be 1/2" so I am not really going to gain anything by doing this I assume but it still saves me the trouble of modifying rads and finding adapters for the pump.

pHaestus,

What do you exactly mean by "You're trying to use a thoroughbred to pull an applecart"?

I know that you are an expert on pumps and watercooling so I take your advice to heart and would like to know what you think about my idea of not using any adapters between the pump and the rads.
If I can stretch some 3/4" ID tubing on the pump inlet and outlet, do you think this would be better or do you still recommend what you wrote?

Also, thanks to everyone that replied.

Follow pHaestus's advice or you waste all that power the pump has on just overheating it.

havn't got mine together (don't have the blocks an such) but I have the pump plumbed and I used 3/4" FPT with 1" barbs on inlet and outlet of the pump and 3/4"MPT with 1" barbs soldered into my 2-342 H/C and have 1"to 5/8 " barbed reducers for the 1/2 to 1"line union going into and out of the tower also a 1" T fitting and line before the inlet of the pump Iwaki MD rlzt 20 so far so good lol

Ive got an MD-15RLT, the housing seems to get very hot. It's hot enough where I wouldn't rest my hand on it for more than maybe 4-5 seconds. I recognize that my setup has a impacted flow rate because the particular radiator I am using drops the flow considerably. Is the amount of heat the on the housing a symptom of the pump having to work harder because of the low flow?

Sorry to hijcack this post but I believe it is within the topic discussion.

Thanks.

_Siph

Siphilon said:

Ive got an MD-15RLT, the housing seems to get very hot. It's hot enough where I wouldn't rest my hand on it for more than maybe 4-5 seconds. I recognize that my setup has a impacted flow rate because the particular radiator I am using drops the flow considerably. Is the amount of heat the on the housing a symptom of the pump having to work harder because of the low flow?

Sorry to hijcack this post but I believe it is within the topic discussion.

Thanks.

_Siph

Click to expand...

I havn't run mine yet but I built a seperate box to house the pump motor in. Open on the pump side an covering the motor and have a panaflow 80 mm 47 cfm fan exhausting out the back behind the motor kind of a wind tunnel . I think this should help keep alot of heat out of the loop ( if I ever get to finish this monster ) lol PS this is the first water cooling setup I've attempted but putting alot of thought an research into it sorry yes the closer you get to a pumps limits of head or gph the more heat the pump generates some where in the middle of a pumps curve is where the pump puts out the least heat

Black_Paladin said:

pHaestus,

What do you exactly mean by "You're trying to use a thoroughbred to pull an applecart"?

Click to expand...

He means that you'll cripple the performance of that pump when you use 1/2"ID tubing for the intake. The pump is able to pull in more water than the tubing will let through, thereby crippling the flowrate & head of the pump. You can combat this my using a resivoir built into the intake or using 3/4" from the HC.

You might wish to read "Influence of suction line on pump performance" section from this article:

Much of the discussion there came from this document

pHaestus said:

You might wish to read "Influence of suction line on pump performance" section from this article:

Much of the discussion there came from this document

Click to expand...

Thanks pHaestus. That was very informative. I am now definately going to build a reservoir for my pump.

Would you think that it would be even better to put the pump inside a reservoir though? Say if I were to build a reservoir out of acyrlic and put the pump inside, how would that work?

My idea is something like this:
http://www.hard-h2o.com/readreview/watercooling/reservoirpump.html

Black_Paladin said:

Thanks pHaestus. That was very informative. I am now definately going to build a reservoir for my pump.

Would you think that it would be even better to put the pump inside a reservoir though? Say if I were to build a reservoir out of acyrlic and put the pump inside, how would that work?

My idea is something like this:
http://www.hard-h2o.com/readreview/watercooling/reservoirpump.html

Click to expand...

i'm afraid that they're not waterproof and therefore can't be used submerged.....

pauldenton said:

i'm afraid that they're not waterproof and therefore can't be used submerged.....

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But I thought Iwakis were used in aquariums.

EDIT: If an Iwaki can't be submerged, could somone give me ideas on how to build a reservoir only for the inlet of the pump? I don't want to build it out of tupperware but I don't know how else I am going to do it.

The person in the article pHaestus linked to is using a PVC pipe but I am not sure on the details of how exactly he constructed the thing.

You could make a res out of 1" pvc with 2 caps 1 glued on one removable for filling. Drill 2 holes, epoxy in a 1/2in barb and a 3/4 inch barb, and have a 3/4 inch barb on the pump and run the big tubing from the res to the inlet of the pump..


like this http://www.ocforums.com/showthread.php?s=&threadid=275438


ghett0 xs p4in7 time

eXCeSS said:

You could make a res out of 1" pvc with 2 caps 1 glued on one removable for filling. Drill 2 holes, epoxy in a 1/2in barb and a 3/4 inch barb, and have a 3/4 inch barb on the pump and run the big tubing from the res to the inlet of the pump..

Click to expand...

eXCeSS,

Nice idea but I do believe that the design you are describing does not really benefit the inlet of the pump. I am saying this because pHaestus is saying that he used the same kind of design in his rig initially but that didn't provide any benefits for the pump.

What we need here is to be able to "submerge" the inlet of the pump in a reservoir so that the reservoir itself is like one huge barb fitting. Otherwise, if we just use 3/4" fittings to connect the pump to the reservoir, then we are restricting the flow with the 3/4" barb and it doesn't matter where the reservoir is placed in the system.

Think about it: Tube connects to the reservoir, reservoir connects to a fitting (1/2" or 3/4" or some other size) and the fitting connects to the pump. For the water to go from the reservoir to the pump, the barb you attached to the reservoir (connected to the pump) has to be used. As a result, the choke point is the barb and the reservoir is only providing a point in the system for filling/bleeding. Imagine just using 3/4" tubing for the pump and not using any barbs at all. This also accomplishes the same exact thing. You could add a reservoir to this kind of system somewhere between the pump and the tubing but it isn't going to make a difference where you put the reservoir because this time the 3/4" tubing that connects to the pump will become the choke point.

In short, unless you can attach the reservoir directly to the inlet of the pump, the reservoir is not going to provide any advantages for the pump. My problem here is figuring out how to build and securely attach a reservoir to the pump inlet without using any barbs like in pHaestus' setup. Will drilling a big hole in a PVC pipe and using goop do the trick?

Or is there a more elegant solution like using just acrylic?

If I wanted to build a cylinder out of acyrclic, what kind of tools do I need and how would I be able to do this? Also, is acryrlic easy to get a hold of? Can I just buy some from Home Depot for instance?

Black_Paladin said:

But I thought Iwakis were used in aquariums.

EDIT: If an Iwaki can't be submerged, could somone give me ideas on how to build a reservoir only for the inlet of the pump? I don't want to build it out of tupperware but I don't know how else I am going to do it.

Click to expand...

i'm sure i've seen a post of the construction of a really nice one by some guy (from hong kong iirc) - i'll post a link if i can find it....

pauldenton said:

i'm sure i've seen a post of the construction of a really nice one by some guy (from hong kong iirc) - i'll post a link if i can find it....

Click to expand...

Thanks! That would be great.

Do you know if Iwakis can be submerged or not though?