What size ducting and what type?

**bitingmidge** · 13th December 2005, 12:15 PM

No, you are drinking a glass of coke with one of those tiny little 2mm diameter cocktail straws, you use a lot of effort and just get a bit of a squirt.

So you put two straws together and suck..... more coke.

Then you get one of those fat Maccas thickshake straws and you get even more drink without sucking much at all.

Now do the same with the straws a metre long, and you'll find you can barely summon the energy to get the drink from the small diameter, but you'll still get heaps from the big one.

Two small diameter ones, still take heaps of effort, but you do get twice the amount of one.

We haven't even got to what happens if you are drinking a Spider and the straw bogs in a bit of ice-cream.

You started this analogy!

Cheers,

P

**Wongo** · 13th December 2005, 12:40 PM

You wanna to pick a fight?

Midge, clearly you missed the point. My example demonstrated the amount of coke you drink is determined by the size of the straw which is the smallest cross-section of the flow.

And so did yours.

**bitingmidge** · 13th December 2005, 12:42 PM

See, I TOLD you I get confused by this stuff!!

P
:confused: :confused: :confused:

**Wongo** · 13th December 2005, 12:45 PM

What are you having for lunch? Tin soup with a straw perhaps?

**bitingmidge** · 13th December 2005, 02:01 PM

Peas, picked up with a straw.

Coffee, drunk through a straw.... ercch, that reminds me of the year or so when the old factial muscles weren't doing what they were told, and I had to do exactly that.

Took the kids to Seaworld, and they have these old-fashioned wax-paper straws, so if a dolphin accidentally ingests one, it'll turn to dolphin poo quite safely... which is fine... until you start drinking hot coffee through one.

Takes about six straws per cup.

Don't use waxed paper for DC ducting.

P

**GregLee** · 13th December 2005, 05:28 PM

It's good to see that any thread longer than a page will always divert somewhere else for a while..

Wongo,

I was looking at making the entire length of my straw wider by either removing the 4 inch connector flange and coupling the 6inch pipe directly to the DC. My Extractor has an 8 1/2 inch flange coupling. Or connecting dual 4 inch outlets from my DC to a 6 inch Main via a Y.

The main reason I was looking at 6 inch mains was to reduce airflow loss over the length of the main and try and keep as much airflow at the end of the run. This is because I wanted to run vertical feeders and wanted as much airflow as possible.

Also, You're right I need to toughen up.. But I live near the beach and the humidity is always high. As is the potential for static belts..

Burn,
Thanks for the piccies shows heaps. Did you try and source any reducing Ys. or did you decide to run the 6inch as close to each machine as possible?

**burn** · 13th December 2005, 05:39 PM

Originally Posted by GregLee

Did you try and source any reducing Ys. or did you decide to run the 6inch as close to each machine as possible?

I didn't know reducing Y's existed (ie 6" in and 2 x 4" out), so I just 'built it' from fittings.

**journeyman Mick** · 13th December 2005, 11:40 PM

Wongo,
if air flow in a DC system is anything like water flow in a pipe then using a 6" straw with a reducer to 4" at either end will give you more flow rate than the same length of 4" straw. It's not just the restriction at one point that slows the flow down, it's the friction of the fluid as it passes through the smaller pipe. Thus, greater length of small pipe = greater friction = less flow.

Mick

**Wongo** · 14th December 2005, 09:30 AM

Thanks Mick

**GregLee** · 14th December 2005, 11:41 AM

Originally Posted by burn

I didn't know reducing Y's existed (ie 6" in and 2 x 4" out), so I just 'built it' from fittings.

Not sure about 6" in and 2x 4" out.. However there is 6" in and 1x6" and 1x 4" out.

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