Thread: Installing my Dusty - WIP

Why seal it? It doesn't really matter if it "leaks" does it?

If I have the end of the duct connected to the table saw and the 9 joints between the hose on the table saw and the impellor leak then surely I'm not getting full "suction"/flow at the saw?
We call this false air entry on intake systems.

Originally Posted by Lappa

Cant wait to get my new system finished and working but I won't be using DWV pipe again if I have to redo at any time.

Does this mean you are not using stormwater or is there some other reason?

RE Sealing.
I used to seal every joint with duct tape but when I tested I could not measure a difference in flow between sealed and unsealed.
Now I only seal non-standard junctions/connections like galv to PVC transitions where the fit is not so good.
It does not mean that there are no losses but they are only a few % of the total although every bit does help.

I ordered the DWV elbows because of the better radius vs stormwater and they supplied DWV pipe as well. It has a lining and is damn heavy. Didn't realise it had a lining until I started cutting it into lengths.
As to losses, its a snap to seal so why not. Guess I keep relating back to auto problems re tract leaks. Obviously the greater the restrictions at the end point, the more problems with unsealed joints

As to the original question, how do you prevent components rotating?

There is a big difference between car and DC stuff.
Car stuff operates at 10's or so of PSI, so if there is a hairline crack in a manifold or pipe this make a significant difference as we found earlier this week when one our vehicle turbo hoses developed such a crack.

2HP DC stuff is all less than 0.3 PSI.
At these pressures hairline cracks can be considered sealed and even bigger gaps e.g. 1mm lose very little flow.
I was quote surprised when I did the measurement and even more surprised when I checked the theory.

For example at full pressure i.e. 0.3 PSI
- a 4 mm diameter hole 3 mm long will leak < 1 CFM - that's why there's really no need to plug holes drilled for tek screw connections if they are drilled in the wrong place.
- a 0.5 mm crack all the way around a 6" junction, and as long as the junction/duct connect (e.g. 60 mm) leaks <0.5 CFM
At working pressure these will all be less than those values.

It's almost certainly worth more spending time on de-restricting machinery (a first order effect) than it is sealing ducting (a third order effect)

Originally Posted by BobL

There is a big difference between car and DC stuff.
Car stuff operates at 10's or so of PSI, so if there is a hairline crack in a manifold or pipe this make a significant difference as we found earlier this week when one our vehicle turbo hoses developed such a crack.

Vehicle intakes, non turbo charged, work at atmospheric or slightly lower between the air cleaner inlet and the throttle plate.
Below the throttle plate they operated from approx -70kPa at Idle and atmospheric or slightly below at wide open throttle.
The air intake from the air cleaner inlet to the throttle body in a naturally aspirated vehicle is a much closer analogy to a dust extraction system than the turbo charged system you have alluded to, and a more relevant comparison.

Originally Posted by BobL

2HP DC stuff is all less than 0.3 PSI.
At these pressures hairline cracks can be considered sealed and even bigger gaps e.g. 1mm lose very little flow.
I was quote surprised when I did the measurement and even more surprised when I checked the theory.

For example at full pressure i.e. 0.3 PSI
- a 4 mm diameter hole 3 mm long will leak < 1 CFM - that's why there's really no need to plug holes drilled for tek screw connections if they are drilled in the wrong place.
- a 0.5 mm crack all the way around a 6" junction, and as long as the junction/duct connect (e.g. 60 mm) leaks <0.5 CFM
At working pressure these will all be less than those values.

This setup is more like the normally aspirated vehicle I was basing my experience on. As I stated earlier, I relate these intake leaks to that that occur in vehicles, and while they may have very little effect on extraction systems, according to your testing, they cause major problems on vehicles which was my concern re the extraction system.

Originally Posted by BobL

It's almost certainly worth more spending time on de-restricting machinery (a first order effect) than it is sealing ducting (a third order effect)

I agree re de-restricting BUT no system is going to be restriction free at the machine. Every little bit helps.

BTW how do you lock your components together which was the purpose of my post in the first place?

Originally Posted by Lappa

BTW how do you lock your components together which was the purpose of my post in the first place?

I use these https://www.bunnings.com.au/zenith-8...-pack_p2409525
And grind or cut the drilling tips off so they don't poke through into the air stream and catch stuff in passing

Originally Posted by Lappa

I will not be glueing as I may wish to dismantle. I will be running a sealant around all the joints but I want to lock the parts so they can't rotate. I was thinking of a couple of self tapers per joint with sealant under the head and around the thread. What do others do?
Cheers

I just wrap duct tape around each join which makes it impossible to rotate (and seals against air leaks).

Ducting, hangers, saddles, braces etc all finished
Once I have the shed all sorted out again and machinery in place and outlets altered, I will measure and order the flexible ducting. Found some good suppliers in Sydney for 160mm flex to suit the pvc pipe but it's not cheap.
In the meantime made two adaptors - one is for 100mm flex and the other is for 150mm flex.

IMG_0291.jpg

Originally Posted by Lappa

Ducting, hangers, saddles, braces etc all finished
Once I have the shed all sorted out again and machinery in place and outlets altered, I will measure and order the flexible ducting. Found some good suppliers in Sydney for 160mm flex to suit the pvc pipe but it's not cheap.
In the meantime made two adaptors - one is for 100mm flex and the other is for 150mm flex.

IMG_0291.jpg

I don't understand the need for the black thing or is that just a mock up?
What about the ClearVue flexy - it slides over standard 150 mm ducting so no adapter needed.
Dang, just realised that's in Brisy - freight is a killer for that stuff.

The "black thing" is a 160 to 125mm reducer. Being hdpe, the dimensions are the OD so 125mm flex fits straight on and the other end fits into a 150mm pipe joiner.
Does the ClearVue 150mm flex fit on 150mm PCV pipe (160mm OD) or is its ID 150mm like Timbecon and Hare and Forbes flex which won't fit std PCV pipe?

Originally Posted by Lappa

The "black thing" is a 160 to 125mm reducer. Being hdpe, the dimensions are the OD so 125mm flex fits straight on and the other end fits into a 150mm pipe joiner.

I don't even like the degree of taper in the standard level invert. so the step on the black adapter is going to hammer your flow [way more than any leaks ].
It will do as an interim measure but I would look at making a longish taper.
One way is to use a piece of 6" duct and cut a series of ~long V shaped slots into the end of piece of 6" ducting using a TS with a retracted blade and then clamp the end down over a former the right size using PVC hoops or wire and gluing the Vs closed.

Does the ClearVue 150mm flex fit on 150mm PCV pipe (160mm OD) or is its ID 150mm like Timbecon and Hare and Forbes flex which won't fit std PCV pipe?

Yes it does just stretch over 150 mm PVC ducting.

Its not what I would can an "easy" fit. It helps if the ducting itself is tapered back and sanded smooth about 10 mm, and a bit of vaseline is used.
I prefer using thread couplers and screw caps - expensive but it's a far quicker remove and refit.
This doesn't work with Clearview flexy as it's too big. The other thing I don't like about the Clearview flexy is its quite soft, similar to CT stuff.
I think the TC & H&F stuff is tougher but not as flexible.


CVflexy.jpg

They are adaptors that I may need on occasion, not all the time


So the flow in this direction is going to be a problem?
125to160.JPG

If so I can do this with some filler

225to160 taper.JPG

Decided to run my 50mm for my power tools along the ducting. It is powered by a Super Vac and runs through a Cyclone. Connects to a 35mm flexi then the power tool.

IMG_0293.jpg

[QUOTE=Lappa;1996122]They are adaptors that I may need on occasion, not all the time
So the flow in this direction is going to be a problem?
125to160.JPG

Yes it does, and filler is worth doing.

Decided to run my 50mm for my power tools along the ducting. It is powered by a Super Vac and runs through a Cyclone. Connects to a 35mm flexi then the power too.

Good idea.