Thread Table of Contents (TOC) - these links will take you straight t these topics and save you scrolling though the whole thred
1) Modifying the Inlet,
2) Testing with Modified inlet and nothing on impeller outlet
3) Modifying the outlet and filter bag attachment.
4) Testing with modified inlet and outlet with no filters attached.
5) Testing a modified 2HP DC with a Pleated Filter
6) Practical testing of the modified DC within a dust extraction system.
7) An inverse Bell Mouth hood entry to the modified DC.
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I was down at the milling yard today and noticed the 2 HP generic DC I bought for the yard some 3 years ago had still not been connected up for use so I borrowed it to do some performance testing.
It's the standard unit I see around in a lot of woodworkers sheds because it does not need a 15 A GPO.
It has one needlefelt bag and one plastic bag.
A black plastic 4" nominal twin or Y-connection/inlet is attached to the impeller but these connections are not 102 mm as would be expected from a 4" connection, instead they are 94 mm.
Removing the Black Y reveals a 113 mm opening with a bullseye inlet guard (More about this later).
On the outlet side of the impeller the opening is 116 mm.
The choke point is the black plastic Y - that would definitely be worth getting rid of.
Next the power ratings.
The name plate says 240V , 7.7A and 2HP (240 x 7.7 = 1848W or 2.46 HP)
However, in stock DC configuration I find it only draws 5.0 A at 238 V.
The naked impeller draws 5.2A at 238V,
Whether the bags are attached makes no difference to the current draw.
The actual power drawn is thus 5.0 x 238 = 1190 W or 1.59HP
Compare that to my 3HP system which in stock format draws 9.4 A at 238 V or 2237 W or 2.98 HP
It appears this 2 HP unit is not actually 2 HP but more like 1.6HP?
I will do some air flow measurements WIGRTI.
[EDIT] Most of the discrepancies between rated and apparent power above and in following posts can be explained by the "Power Factor' of AC powered motors. If you want an explanation of this check out post #304