Anyone enlarge their inlet port to 6" on HF, 2HP dust collector?

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kooshball

David
Corporate Member
The 2HP HF DC system has a factory 5" inlet port on the housing with a rectangle outlet reduced down to a 5" hose. It would be easy to make a new inlet port with some MDF and a 6" flange as well as convert the outlet to 6" but would I gain anything? is there a ratio of inlet size to impeller diameter that must be maintained?
 

MrAudio815

New User
Matthew
That's a good question. I can't wait for some opinions/answers.

I had a hard time finding 5" hose/connectors at lowes....I didn't find any.

I had to buy a 10' 5" hose from amazon. And I only needed 1.5' to reach. Oh well.


Matthew
 

ehpoole

Administrator
Ethan
I'm afraid I can't offer any advice as to what the optimal size inlet for your DC might be, but there are 2 major criteria used in dust collection trunk design: 1) CFM - Cubic Feet per Minute of airflow required and 2) the minimum air speed (generally aim for around 4,000 ft/min or 45 miles/hr).

I have a 2HP JDS Cyclone (a true 2HP, 11-12A @240VAC) with a 14" impeller and an 8" inlet if that helps you any. It is also rated at 1200-1450 CFM at the 8" inlet. I have no idea what the real specs of a Harbor Freight DC might be, but if any of this helps you then it is worth mentioning. That said, I personally can't imagine that enlarging it from 5" to 6" would incur any serious consequences so long as you make all the inlet transitions perfectly smooth so as to maintain laminar airflow (if it is a cyclone, probably doesn't matter so much in a single stage).

The important thing is never to run Dust Collector (or any centrifugal/squirrel-cage fan) motors without the proper minimum intake/exhaust resistance (the hose and filter material provide this resistance). As counter-intuitive as it may seem, you can overload the motor by running it without the designed resistance -- which is probably even more true for a low-budget HF motor that it is for a higher-end model.

5-inches really is a rather odd size for workshop dust collection in North America, makes you wonder why they don't include a 4" reducer with their DC?
 

NCPete

New User
Pete Davio
5-inches really is a rather odd size for workshop dust collection in North America, makes you wonder why they don't include a 4" reducer with their DC?

my HF DC did come with a reducer, makes the 5" input a twinned 4" input. do they not ship with this adapter anymore?
 

junquecol

Bruce
Senior User
The important thing is never to run Dust Collector (or any centrifugal/squirrel-cage fan) motors without the proper minimum intake/exhaust resistance (the hose and filter material provide this resistance). As counter-intuitive as it may seem, you can overload the motor by running it without the designed resistance -- which is probably even more true for a low-budget HF motor that it is for a higher-end model.
I disagree. When a blower is "starved for air", the load on the motor is lessened. Take an amp meter and take readings with all blast gates closed, and with all of them open. With them open, the blower is doing more work. Air has weight. Go to the second floor of the Air and Space section of the Smithsonian, and look at the pile of rocks that represents the weight of the air in the building. The motor speeds up, or at least makes less noise, because it is doing less work when the gates are closed.
 

ehpoole

Administrator
Ethan
I disagree. When a blower is "starved for air", the load on the motor is lessened. Take an amp meter and take readings with all blast gates closed, and with all of them open. With them open, the blower is doing more work. Air has weight. Go to the second floor of the Air and Space section of the Smithsonian, and look at the pile of rocks that represents the weight of the air in the building. The motor speeds up, or at least makes less noise, because it is doing less work when the gates are closed.

Not to nit-pick, but unless I am totally dense, did you not just confirm my point? :icon_scra

Most of the DC manuals I have reviewed specifically state not to run them with an unrestricted intake and/or exhaust due to potential overloading and overheating the motor.

Not trying to start any arguments here, but I just can't see any difference between what you say in your comments and what I say in mine.
 

DonDeJ

New User
Don
For a given CFM, the larger the hose, the lower the velocity of the air, so you need to make sure you have enough velocity to keep things moving. Where I used to work, we had a 4 bag (two up, two down) DC, not sure of the HP, but we had the 5" reduced to (2) 4" inlets, with blast gates on each so only one got used at a time. That machine sucked great. There was also a garbage can chip separator on it. It would take anything we could throw at it.

I think a 6" hose wouldn't have worked as well because of the lower velocity. Besides, 4" hose is less expensive.
 

Warren

Warren
Corporate Member
Before cyclone (BC), I enlarged A Delta 50-850 from 2 4" inlets to 1 6". I was able to collect from a 15" planer about 20 ft. away with a garbage can separator using 6" rigid piping. Never had a problem. It's still in use occasionly, but with 6" hose. Moving to larger basement, I now have a "cleartvue" cyclone.
 
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