Our Mens shed was given a twin bag 3Phase 3HP DC from a local high school.
When I heard about it I was excited that it could be a good unit but subsequent investigations have proved something. . . . . err. . . . . . . well you'll see..
This is what it looked like when we picked it up.
The first thing I did was empty and cleaned out all the bags
The calico bags went though the washing machine twice and came out almost snow white.
The DC is going to be outside so I'm not worried about the fact that it uses the calico bags
The next thing was the rust in the bottom of the frame, so I took it apart, and took the bulk rust off with a wire and applied some phosphoric acid and a coupe of coats of paint.
Next thing was the collection bags. The bags are mad elf that crappy polyester canvas tarpaulin material and are full of pinpricks.
Remember the bags have been emptied but there was still some residual dust in the seams and it came pouring out when I first turned it on.
This is what was deposited on the table after the empty DC was running for a couple of minutes.
Remember this bag is empty and was just the residual dust that was in the seam.
I was just going to replace the collection bags with standard DC plastic bags but this DC is not a standard size so the plastic bags would have to be custom made
Fortunately a couple of members have industrial grade sewing machines and can whip some up from some heavy duty something.
Anyway I left the blue bags on the Dc for the moment so I could continue the testing
One of the bag clamps was missing and the others were POS long hose clamps like this.
So I rang around to see if anyone had clamps that would fit - no luck it's a non standard size (new standard size clamps cost $28 each :oo:) so I made some like this.
Thats an $8 adjustable cam latch, purchase from a trailer parts shop, pop riveted to a pice of galv steel banding (cost me a few cents as I have 100m rolls of it in the milling yard) and it works better than a bought one because the adjustment is finer, why don't they make them all like that? BTW there are smaller ($6) ones available that would probably work just as well.
OK - now I can connect the bags on so I can fire up the unit.
The bags must be connected otherwise the fan may draw too much current and burn out the motor.
See how nice and white the bags are!
Here is the other end. I don't have 3P power at home but I have half a dozen spare VFDs (one is the dark grey box in between the two bags) so I connected up a 3kW (4HP) VFD to the motor so I could see what happens at 60Hz. BTW the Crompton Parkinson motor is true 240/415V ∆/Y connected motor.
The impeller is only a 12" straight vaned construction and these are known to be quite loud and sure enough it is.
At 50Hz it puts out 93dB at 1m, and draws 7.1A (that's not quite 3HP in my book, more like 2.5HP)
At 60Hz its 97dB and draws 12.1A which makes it closer to 4HP.
We will be putting this DC outside it in a noise enclosure anyway but its going to be tough to get those dBs down to something reasonable.
Next was the static pressure test.
To do that the intake is blocked and a pressure meter is used to measure the max suck of the impeller.
AT 50Hz it's only 6.5" of WC while at 60Kz it's 8.5" - there could have been some leaks in the system so I will repeat these tomorrow.
However, the impeller is too small and poorly designed so I doubt it will be much higher that this.
More as I get time to deal with it.
When I heard about it I was excited that it could be a good unit but subsequent investigations have proved something. . . . . err. . . . . . . well you'll see..
This is what it looked like when we picked it up.
The first thing I did was empty and cleaned out all the bags
The calico bags went though the washing machine twice and came out almost snow white.
The DC is going to be outside so I'm not worried about the fact that it uses the calico bags
The next thing was the rust in the bottom of the frame, so I took it apart, and took the bulk rust off with a wire and applied some phosphoric acid and a coupe of coats of paint.
Next thing was the collection bags. The bags are mad elf that crappy polyester canvas tarpaulin material and are full of pinpricks.
Remember the bags have been emptied but there was still some residual dust in the seams and it came pouring out when I first turned it on.
This is what was deposited on the table after the empty DC was running for a couple of minutes.
Remember this bag is empty and was just the residual dust that was in the seam.
I was just going to replace the collection bags with standard DC plastic bags but this DC is not a standard size so the plastic bags would have to be custom made
Fortunately a couple of members have industrial grade sewing machines and can whip some up from some heavy duty something.
Anyway I left the blue bags on the Dc for the moment so I could continue the testing
One of the bag clamps was missing and the others were POS long hose clamps like this.
So I rang around to see if anyone had clamps that would fit - no luck it's a non standard size (new standard size clamps cost $28 each :oo:) so I made some like this.
Thats an $8 adjustable cam latch, purchase from a trailer parts shop, pop riveted to a pice of galv steel banding (cost me a few cents as I have 100m rolls of it in the milling yard) and it works better than a bought one because the adjustment is finer, why don't they make them all like that? BTW there are smaller ($6) ones available that would probably work just as well.
OK - now I can connect the bags on so I can fire up the unit.
The bags must be connected otherwise the fan may draw too much current and burn out the motor.
See how nice and white the bags are!
Here is the other end. I don't have 3P power at home but I have half a dozen spare VFDs (one is the dark grey box in between the two bags) so I connected up a 3kW (4HP) VFD to the motor so I could see what happens at 60Hz. BTW the Crompton Parkinson motor is true 240/415V ∆/Y connected motor.
The impeller is only a 12" straight vaned construction and these are known to be quite loud and sure enough it is.
At 50Hz it puts out 93dB at 1m, and draws 7.1A (that's not quite 3HP in my book, more like 2.5HP)
At 60Hz its 97dB and draws 12.1A which makes it closer to 4HP.
We will be putting this DC outside it in a noise enclosure anyway but its going to be tough to get those dBs down to something reasonable.
Next was the static pressure test.
To do that the intake is blocked and a pressure meter is used to measure the max suck of the impeller.
AT 50Hz it's only 6.5" of WC while at 60Kz it's 8.5" - there could have been some leaks in the system so I will repeat these tomorrow.
However, the impeller is too small and poorly designed so I doubt it will be much higher that this.
More as I get time to deal with it.
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