Thread: Dust extractor vacuum pressure drop

I sounds like you have a blockage somewhere.

A dust collector isn't meant to be reduced that radicly. I connect my sander to a 2hp dc and this only works because there are 2 55mm ports, otherwise I wouldn't get the volume to suck.

A dc is the opposite to a vacuum cleaner in that they use pressure to suck.

Maybe someone can explain it a bit better than I.

Robert

the smaller your hose the greater your pressure drop. I haven't got the tables in front of me but a metre of two inch hose would have somewhere in the vicinity of the same pressure drop as 3 metres of 4 inch. it is jst a fact of life

Thanks but there is no blockage. Checked all pipes and ran a rod or wire through them - all clear.

I reckon Canetoad is on the money, how long is the hose?

All I am trying to do is use thedust extractor to collect dust from my orbital sander or router or bandsaw.

The 2" hose is 1.5 meters long.
Attaching this hose directly to the unit causes the same severe pressure drop.

I used a PVC plumbing fitting to bring the2" up to 4"for a sealed fit.

Originally Posted by digitalis49

All I am trying to do is use thedust extractor to collect dust from my orbital sander or router or bandsaw.

Run the 4" hose as far as possible before dropping to 2". (I guess by "orbital sander" you mean you are locating the hose nearby, not attaching to the sander somehow).

Sounds like you are trying to get a dusty to do a shop vacs job. My understanding is that dustys are useless on the smaller hose diameters as they are a high volume low pressure machine. Shop vacs on the other hand are a high pressure low volume machine perfectly suited to your router and sander takeoffs.

Get your self an old vacuum cleaner and make a mini bucket cyclone to run between the vacuum cleaner and the dust producer. This will stop the bag from filling and reducing pressure. There are few threads on this somewhere.

What Canetoad and Burnsy said, D/C are designed to move volume not vacuum pressure, so when you reduce the inlet it restricts the volume therefore the vacuum pressure drops off.

Originally Posted by digitalis49

The 2" hose is 1.5 meters long.
Attaching this hose directly to the unit causes the same severe pressure drop.

I used a PVC plumbing fitting to bring the2" up to 4"for a sealed fit.

Try this:

Breath in a big lungfull of air, expel.

Now put a small hose in your mouth and take the same big breath - nowhere near as easy. Not trying to be a smart asre, just trying to explain it.

A 1hp motor simply is not that strong, it is designed to move large volumes of air at low velocity, not small volumes at high velocity which is what you are effectively doing with the smaller hose. Your best result may be to use the coverter connector right at the machine from a 4" hose, even then it may struggle. What brand machine is it btw?

Iam really grateful for all your king replies. It is important to me that you know this.

My unit does not have a cfm rating but the vacuulunit is cast iron coupled to the 1hp motor. The impellor is steel, undamaged and is 18" in diameter.

I thought it would be capable of working as a mini shop vac.

My sander, router, and some other tools have hose attachments for vacuum.

Thanks again. My unit is an EMCO DC5 but I replaced the 1/2hp motor to 1hp.

With a big impeller like that I would be trying to hook up a 2 or 3 hp motor.


Sanders need shop vac or old vac.
Use a pre separator even a lidded bucket with an in and out pipe.

The old amway vacs have a cyclone built in.