Triton dust collector

[frank]

i got a plastic bin from ikea and fitted a vacuum cleaner to the lid the inlet went in the side of the bin this makes the air swirl round in side the bin the bin cost about a fiver the vac a couple of quid from the car boot it works but its a bit noisy (who said vacs are quiet :shock: )

frank.

 

[Johnboy]

Keith, I understand now but it does not matter how high a column of water the machine can lift, the positive pressure on the outside of the bin can never exceed atmospheric pressure ie. 1 bar. I don't know how good a vacuum you can get in an extraction system but it will be nowhere near a perfect vacuum. Still from other posts it is obviously enough to collapse a plastic bin.

When I get round to putting my extractor in a workshop extension I intended to build some sort of cyclone/extender. Some experimentation is on order!!

John

 

[ike]

Keith wrote:

a suction machine of the type made by Camvac will support approximately twice that (2bar) or as ike correctly said 2000mb.

Parachute - Check!, Ejector seat - Check!

Er, no, I said 220 millibars - that's 0.22 bar. A 'suction' cleaner (that sounds a perfectly logical name for it) will reduce atmospheric pressure by approximately four fifths. So thats about 6'-6" water column 6-1/2" of mercury, 3psi, or 0.2bar whichever way you measure it, it's less than 1 bar. If the Camvac produces 2.08 bar of suction, (a) it's a contradiction of terms, and (b) I suspect it'll blow everything out of it's a***! :shock:

Ike

 

[dedee]

and it collapsed very easily if you blocked the hose.
Andrew

I notice that the instructions for the LV lid (see link from Alf) recomend a small (3/4" relief hole is drilled in the lid which would have prevented this. Quote from LV
"It will cause negligible loss of efficiency (equal to a hole less than 0.005" diameter in 2-1/2" hose) when air is flowing, but will provide enough relief to prevent the lid from inverting when the flow is blocked".

AndyP

 

[mudman]

I think that the Camvac's 2.08bar of suction could be accurate.
Ok, working from memory here so could be wrong, sombody please correct me if so...
A pump's power is usually measured in terms of the height of a column of water that can be supported on the outlet side (the static Head). This would be measured on the outfeed side of the pump with the outlet blocked and so the static pressure is measured.
What Camvac is saying is that their machine can create a pressure of more than two atmospheres on the outlet which would be a static head of 1520mm of Mercury (if I recall correctly), don't know what this is in terms of a column of water.
What this means is that the Camvac is a pretty powerful machine because to create this kind of pressure it has to be able to shift a load of air through itself and consequently a bigger 'suck' at the infeed side.

 

[ike]

Mudman wrote:

I think that the Camvac's 2.08bar of suction could be accurate.

I think you could be right but technically it would be 2.08bar of discharge pressure which then results in a measure of suction pressure at the inlet.

 

[mudman]

Been thinking again...

I don't know how good a vacuum you can get in an extraction system but it will be nowhere near a perfect vacuum. Still from other posts it is obviously enough to collapse a plastic bin.John

Of course, as somebody said earlier, the vacuum in vacuum cleaner is a misnomer as it doesn't create a vacuum. Whilst there is an open inlet, then if you suck out all the air from the bin, then it will be replaced with an equal amount of air. In fact, I think that the pressure inside the the drum is probably still close to atmospheric.
What you have got is a very fast, high volume throughflow of air, it is this movement of air that creates the suck, not a vacuum.
Now, if you block the inlet, then the air in the machine is very rapidly exhausted creating a pretty good vacuum inside, this means that the bin has to then withstand the whole weight of the atmosphere above it and if it isn't up to the job, then the several hundred miles of air on top of it causes it to crumple very nicely.

Cheers,
Barry[/i]

 

[ike]

Following on, while the air flow is constant, then suction pressure must vary according to the cross section of the airflow. So the lowest pressure will be in the inlet hose (the 0.2 bar or thereabouts. The pressure will then rise in the tank, but by how much - who knows. I think this is known as the Venturi Effect isn't it?

 

[mudman]

Yes, effectively, the hose and the bin will be a big Venturi thingy. However, the pressure changes in the hose and tank will not have any effect on how much dirt it can pick up. There will be two things that will cause dirt to move into the hose, the first will be the friction caused by the movement of the air against the dust particles, but the main effect will be the acceleration of the air at the hose opening, this will cause an area of low pressure, due to Bernoulli's Principle, that will suck the dirt into the airstream. Then, when in the airstream, it will be carried along by the friction effect.
Now, in general, the hoses of vacuum cleaners are the same size amongst units, so the only way to increase pickup power, is to increase the volume of air passing through the hose. If you increase the volume, then you increase the velocity, doubling the volume will increase the velocity for the same cross-section.
So, if you want to compare vacuum cleaners, then it is probably more sensible to use airflow rates rather than pressure values as a cleaner that moves twice as much air will have twice as much suck.

Does that make sense? :?

Cheers,
Barry

 

[Alf]

I notice that the instructions for the LV lid (see link from Alf) recomend a small (3/4" relief hole is drilled in the lid which would have prevented this.

Good catch, Andy. I missed that one myself. BTW, I like the avatar, but should lawnmowers pup? :lol:

Cheers, Alf

Not geared up to cope with all these technical threads at all :shock:

 

[MilkyBarKid]

OK, forget the word vacuum and call them suction machines.

I'll have a go at explaining this then wait to get shot down :roll:

Atmospheric pressure will support approximately 10metres of water (1bar), a suction machine of the type made by Camvac will support approximately twice that (2bar) or as ike correctly said 2000mb. Sorry ike, I'm used to using bars for pressure from scuba diving.

Keith - I'm not sure I understand your terminology here - but, as I understand it - with an atmpspheric pressure of approximately 1 bar - ( anyone know the metric equivalent in hectoPascals - thought not - me neither!! ) you could power your vacuum cleaner with a merlin engine but it's still not going to lift more than 33ft of water.

 

[Keith Smith]

One disadvantage of getting older is that your eyesight goes and I have misread the specs on the Camvac machines

I thought it read Vacuum 2080mb but;

The specifications actually state;

Vacuum mm H20 2080mm

Which I assume means that it will support 2080mm of water in a column, a bit different than 20 metres :roll:

Sorry.