Thread: Fibreglass Cyclone Project

Top job Muchacho.
Do you still have the molds? I reckon you could earn yourself a bit of cash there. Especially if it uses a readily available and fairly cheap DC as the driving component.

Brilliant work!

Have you thought about upsizing the bin? Yours looks very small, you might need to empty it very often. Mine is around 160L.

Looks good muchaco.
It would be interesting to know the static pressure of your system.
In fact I would encourage all modifiers or constructors to provide at least that piece of information as it is easy to manufacture a manometer and measure the pressure generated.
The nominal flow rates can then be determined from charts and would be a more useful point of comparison than just "it works good"

...vely implessive indeed
As stated, hope you kept the molds for some extra tool money. I'l put my hand up for one.

Very nice work and as Bob said, Ii would be great to find out how efficient it is via a thingymajig meter.

Originally Posted by Muchacho

With the overriding constraints of cost and limited electrical supply restricting me to a 2HP system it was important to make it as efficient as possible. With this in mind I chose to use a cyclone venting outside without any filtering and to restrict my inlet ducting to as short and straight a run as possible without blast gates. ...

The cyclone itself is around 450 dia by 1300 tall and built more or less to the Bill Pentz ratios. As I don’t have the required skills and equipment for a sheet metal build, I opted to construct this out of fiberglass. In order to gain maximum efficiency, the shape chosen provides an inlet ramp and neutral vane. Although a fair bit or work went into the molds I am very pleased with the end result as I know I could never produce anything similar in any other material.

I like it very much , Muchacho.

Just a couple of thoughts: I havent gone back to Pentz's website to check but I think he recommended a diameter of about 550mm for the optimum size for a cyclone with a 1 or 2 hp impeller but somewhere around the size you have made for 3+ hp impeller units.

A lot of course depends on the other factors involved in the overall system, My homemade cyclone is inside 2 x 44 gallon drums and so has approximately the right diameter for the 2hp impeller I use as well as the previous 1hp impeller I used to use.

Electrical power constraints have been a major driving force in the shaping of my DC strategies too and interestingly we have both opted for our own versions of a cyclone, the elimination of dustbags and filters in favour of venting straight outside.

Well at the end of August, I get to relocate all my workshop again. We have the new house picked out and I can still set up similar to what I have now. The shed has a window I can vent out through. If I am feeling energetic I might start a WIP dust collection build as I do the new setup.

Cheers

Doug

Hi Muchacho,
Very good job, you used your skill and knowledge and applied that knowledge to solve a problem (no cyclone) well done

I would find the bin a bit small as well

A very quick and simple monometer....1m of 5mm clear pvc (or similliar) tube, here's one I prepared earlier
basic manometer.jpg


Pete

Thanks for all the responses, I'm pleased that it has created some interest.

Regarding the size of the various components, I think I alluded to the fact that one of my constraints was my ceiling height. This results in the bin being slightly shorter than what I would prefer as it was either do this or make the cyclone shorter. The bin volume is about 50 litres which works fine for me with regards to disposal as it suits the standard black rubbish bags which can get into the household rubbish wheelie bin.

When I get some time I will knock up a simple manometer and report back.

I still have all my moulds and have considered making some more. I guess whether this happens will depend on what people may think it is worth.

Very impressive indeed.

I look forward to seeing the manometer results. In fact I have been moved to hook up a manometer to measure my own system. Can anyone let me know the "traps for new players", especially in how to connect the manometer to my ductwork?

One leg pokes into the pipe thru a drilled hole in the main line and if possible close to fan/cyclone, (neat fit is best) at 90° to the flow to be tested and the other is open to atmosphere, fill with water allowing enough free length for water movement up the column say 5" up and 5" down should cover it, although more won't hurt, worst that will happen is you'll suck some water into the system, the manometer to be orientated vertical, use a food dye if it's hard to see the water, make sure there are no gaps (bubbles) in the water column, shake or tap the columns to remove bubbles, then test. An improved version of a manometer can be made attached to backing with it's own scale/rule, a quick google should find a few piccies.

I would turn DC on (with all gates closed) without tube poked in and then cautiously offer the tube to the hole and watch the water rise, I do this so I can judge whether I have enough free length for movement, it will move quickly, adjust if needed to give free length without water being sucked into system, i.e. less water or more leg length.
Then make a series of tests, for each test you measure the difference in hieght between water in each leg, e.g. one leg moves up 50mm, other moves down 50mm for a total of 100mm, this number is then used in conjunction with the chart to guage flow etc. with the first setup you are measuring the max. pressure your system will generate plus leaks within the system, to isolate the system blank off as close to the manometer as possible, this then gives a more accurate measurement of fan only and it's max pressure, then it's a matter of testing each branch/machine with gate open (others closed) then I would open up further gates (one at a time) to reach a point where opening up another gate doesn't produce a lowering of hieght in water, this is then the max flow the fan/system will flow, next I would see what difference various fan speeds made on flow with corresponding current draw, (((but that is moving into sparky area))) for more accurate testing of each branch you could then repeat the setup on each branch and then any multitude of test configurations if you wanted, e.g. with hose on, hose off, machine holes blocked off/open etc. There may not be enough difference in test hieght for this sort of testing, to improve the manometer sensitivity it is orientated towards horizontal (on it's side) but this is moving into BobL's area with more test gear/gadgets.



I think that covers it, BobL may have some more insigtht....


Pete

Thanks Pete.

I'll buy some clear tube and hopefully run the first tests this weekend.

Pete has provided useful information.

Static measurements must be done with the DC running but no flow so you need to be able to seal that section of the ducting off from the atmosphere all the way back to the impeller.
Lets say you have a ducting arm to a machine consisting of 3 segments (A, B, C) and they are connected to the impeller (I) and machine (M) in the following sequence ( I A B C M).
Step one is to measure the pressure just inside the impeller mouth (ideally you need to disconnect the impeller from the ducting to do this) this should be the largest pressure value you get.
To measure the pressure available at the machine you should disconnect and block the ducting at the machine and measure the pressure at that point. If you have no leaks the pressure should be the same.
If not then check for leaks at the junction of AB and BC and attend to these until you get the same value. The biggest pressure loss contributors I find is blast gates.

Remember that using pressure readings and the pressure/flow chart that I posted on this forum only gives you the theoretical max flow for the smallest duct diameter on this. If your system has a long/ tortuous path or a choked machine, or even just uses a naked duct opening as an inlet, the actual flow will be less than this. To measure actual flow the system must be flowing and dynamic pressure measurements must be measured using a something like an anemometer or pitot tube.

I connect my manometers to the ducting those small 4mm black retic tap threaded fittings and drill and tap the ducting in appropriate places and then seal the connection thread with Loctite.
After the measurement is done the taps seal the hole and they enable the static pressure to be easily checked at any time later.
I also have a set of PVC threaded caps in various sizes with taps in them to check temporary setups (see photo below).
The small PVC one is used to test VCs, the brass ones I used to check mains gas pressure while setting up my gas powered forge.

Also shown in the photo is my digital manometer ($60 on ebay) which is much easier to use than a water column manometer.

OK,

First measurements taken. I used clear 8mm PVC hose. First sample point was in the ductwork as close to the cyclone as I could get. With all gates closed I got 297mm of water. Second sample point was at the very end of my longest run, again in the ductwork. I got 293 mm of water. I am guessing the delta is caused by the five blast gates.

The following results were all taken from the sample point close to the cyclone. I tested everything twice. Once at 60 Hz and once at 50 Hz, but I routinely run the cyclone motor at 60 Hz. The machines in the table below are laid out from the longest to the shortest run.

Air Flow details	mm of Water
at 60 Hz	at 50 Hz
All Gates Closed
Linisher	170	125
Table Saw	155	112
Drill Press
Drop saw	164	118
Drum Sander	170	122
One Open Port (no Machine)
All Ports Open

To test the integrity of the data I correlated the 60 and 50 Hz data when air was being drawn through a machine. The r-squared factor was 0.9461 ... not to foul at all.

Originally Posted by John Samuel

OK,

First measurements taken. I used clear 8mm PVC hose. First sample point was in the ductwork as close to the cyclone as I could get. With all gates closed I got 297mm of water. Second sample point was at the very end of my longest run, again in the ductwork. I got 293 mm of water. I am guessing the delta is caused by the five blast gates.

Were the above pressure readings for 50 or 60Hz?

Is the data for the machines taken with the duct at the inlet of the machine blocked off?

As promised, I knocked up a simple manometer to my fibreglass cyclone system, with a pressure tapping just upstream of the fan inlet and took a number of readings in the following configurations.

1) Inlet sealed, fan only at zero flow 6.5"

2) Fan, cyclone, 2.5m pvc and 3m flex, fibreglass fitting and thicknesser 3.4"

3) Fan, cyclone, 2.5m pvc and 3m flex 2.4"

4) Fan, cyclone, 2.5m pvc (no flex), 1.25"

The above setups also include the 400 x 600 louvred outlet through the shed wall.


The first reading was not really any surprise, as this seems about the standard 1000 cfm as per BobL's previously published chart.

I'd be interested if anyone has a pressure vs flow chart for a 2HP fan. Would be interesting to see if the 3.4" reading is anywhere near the suposed minimum 800 CFM at the machine.

The final reading has blown me away. According to Bill Pentz, a cyclone built to his design with neutral vane and inlet ramp should be about 2.25".

Have to say this has made my day as it appears that I may have met my objective of making an efficient system to compensate for the less than ideal fan.

Now, what would this thing do with a 3HP fan ???