reducing iwaki pump inlet/outlet
 

ive just ordered an iwaki MD30RZ. it has male threaded 3/4" inlet/outlet. i was wondering, how can i put 5/8" barbs on this? is there some kind of reducer/special fitting that will do this?

Can't wait to see how you like that pump, and where you're gonna put it! Anyway, just get some threaded barbs, I know home depot has them. Just make sure to use teflon tape on the threads.

you mean threaded on the inside?

You'll need a female-female adapter, since most barbs have a male connection. Otherwise if you can find the right barb, good for you!

I'll be real interested in seeing any results you'd care to post here for us. Cathar's block is real good and that is one of the more powerfull pumps, be a great combo.:drool:

What size is the heater core? Or just post the Fedco # please.

M3_arun is planning on a chevette core.

Thanks BigBen !

I'm real interested to see how his system performs.

ya i will keep everyone updated on any progress. i am sending the money for the pump today. ill be getting the block when cathar comes here to san jose.

do NOT restrict the pump inlet
feed it directly from a close-coupled res with a big pipe
pHaestus' res was/is excellent
try 1 1/2" Cu pipe with a bell reducer to 3/4 FNPT right at the pump inlet

I'm gonna throw a stupid question at that...

Volenti (?) mentionned (at OCAU) that measuring the pump head is different wether the pump is submerged or not: something to do with the water having to speed up into the pump inlet (when submerged).

My Q: is there such a thing as too big an inlet?

no
look at the distribution or resistances through the fluid circuit
what needs to be avoided is a (pointless and unnecessary) resistance at the pump inlet

centrifugal pumps are not designed to lift from the suction side

no idea what Violenti was referring to re the head
could be a measurement 'problem'

why the pipe?

how about a res. built around the pump-inlet with a big hose barb? would that work?

"a res. built around the pump-inlet" sounds good; like what pHaestus did ?

where is this barb going to be ?
(not on a 5/8" hose connecting the res and the inlet I hope)

no i mean the barb coming out of the res.
would it be too restrictive to have a barb directly on the inlet?

The measurement 'problem', is not having an accurate way to measure the flow in an in-line circuit, so all I can do is speculate about it

though a res may store the same energy as potential kenetic, so the 2 systems may end up having no advantage one over the other anyway...

Found the FEMALE hose barbs you'll be wanting, in the proper sizes at Mcmaster-Carr.

Link www.mcmaster.com

Page 1 under barbed tube fittings

Billa is right about not restricting the inlet. Found that one out the hard way :(

That Sedra 3500A that I got was noisy as hell and after trying to work with it for about 2 months I gave up and bought an Eheim 1250. That Sedra had almost a 1" inlet and a 3/4" outlet! Tried to reduce it to a 5/8" inlet and a 1/2" outlet; the pump turned into the noisiest part of my whole setup (could not even hear my Sunon 108cfm fan over it)

Eventually I might use that pump for an external water chiller some day but till then it is collecting dust and I am enjoying the silence of the Eheim.

McMaster is exactly where I got my 3/4" NPTF x 5/8" Hose connectors, which I am using on my MD-20-RZT. The inside diameter of those fittings is exactly the same as the inner diameter of the inlet inside the 3/4" NPT connectors on my pump. I don't know about the 30, but I know that you can buy the 20 with a 5/8" barb to begin with.

thanks for the info, balckeagle and skulemate. ive been looking for those. will the 5/8" barbs be too restrictive or are they ok?

I myself would use the larger 3/4" lines. And if you can manage it, fit wise, then I'd also run a large line from the res to near the pump like BillA suggested.

Anything to maintain a high flow rate.

also can someone clarify on that? what is a bell reducer?

This is only a guess, but I would assume that it is an adapter that provides a smooth transition from one ID to the next. This would reduce the amount of losses in the fitting compared to a sharper transition (like those PVC ones you can get at Home Depot).

That would be correct.

A sharp transition is actually more restrictive. It can be googled with the terms: "orifice plate", but I haven't had a lot of luck with that.

hey skulemate:

I just opened Outlook and noticed an extremely old item in my todo list:

"mail Mike Robbins maxim ic"

Still interested in this?

Re: suction line restrictions

Might wanna read through this: http://www.cepmagazine.org/pdf/050252.pdf

Pretty clear reasons why not to.

Nice to see my homies published! (KBR is a division of the company I work for).

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

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

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 ;) ).

How's it coming along?

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.

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".