Need help to calculate how much better (CFM) is one air filter vs the other (Truck air filters)

[MiniMe4Eng]

I have this Dust Collector (wood working)
The filter is 5microns and my garage all covered in dust because of the inefficiency of this filter.
I have been using a 3M respirator when the things got really bad and I did a lot of work (this is a DIY workshop)

I am now trying to replace the original filter (a bag) with an high efficiency air filter but still pay a decent price for the filter
The woodworking community has been testing various filter models.
The gold standard are the Whynn environmental filters but they are going to cost more than the table saw or the dust collector I have
The alternatives are Donaldson Truck filters which are also 0.5micoron and 99.9 efficiency
- Donaldson P181099

Efficiency: 99.9
Inner Diameter: 9.49
Length: 18.06
Outer Diameter: 13.84
Overall Length: 18.56
Style: Round​

-Donaldson P181038

Efficiency: 99.9
Inner Diameter: 11.07
Length: 23.06
Outer Diameter: 17.58
Overall Length: 23.56
Style: Round​

The dust collector is a 2HP Harbor Freight

SKU(s) 97869, 61790, 45378
Brand CENTRAL MACHINERY
Flow rate 1550 CFM
Volume 70 gallon
AC Volts 120
Amperage 20
Certification CSA, ETL
Horsepower 2
Inlet size 4 in.
Product Height 75-1/2 in.
Product Length 33 in.
Product Weight 100 lb.
Product Width 22 in.
Shipping Weight 98.00 lb.
Filtration (microns) 5 microns​

My question is this: how can I objectively calculate what CFM rate can the Donaldson filters deliver?
P181099 seems to be larger but I am wondering if the DC will benefit from that or maybe P181038 can already match the dust collector CFM?

 

[MiniMe4Eng]

Are we talking about the same bag?
I am talking about this one (the one on top)

 

[Compositepro]

Yes, same bags. But saw dust is easy to capture, so a filter cake is less important.

 

[LittleInch]

Well if you're all so good at woodwork, why don't you make a filter housing that means the filter works better?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[MiniMe4Eng]

Well ...I am not that good, not sure where I implied that
However I would consider the idea.
It all comes down to finding an appropriate garbage can or other type of plastic recipient

This would be the setup

 

[LittleInch]

Is that still inside to out?

You can just buy a housing for the filter, but they look a bit pricey if you're doing it yourself. Like this

https://www.donaldson.com/en-us/engine/filters/products/air-intake/cleaners/era/

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[LittleInch]

I would still have the system blowing air through the filter not "sucking it" through

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[EdStainless]

I read that as out-to-in, the fan is sucking air through the system.
The drum is for settling of coarse materials (hopefully with some baffles inside of it).


= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[LittleInch]

Ed - it will probably work that way as well. It's the way most vacuum cleaners work.

I can't imagine a fan like that will generate much in the way of differential pressure so won't really make any difference.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[MiniMe4Eng]

@LittleInch

I would still have the system blowing air through the filter not "sucking it" through]

This is what the truck does, right ? It sucks air through the filter
Of course I could imagine a way to blow air through the filter as well

If you ask me the current setup of the Harbor Freight DC is not the smartest one as it sucks dust and debris through the impeller and from there is is pushing it out to the bag filter and that proto separator they have
So practically the impeller could be hit by a piece of wood if it gets sucked in the system -I did hear some impact sounds in a couple of occasions when some debris was sucked in
The above setup will protect the impeler in that sense AND the whole thing is more compact this way

 

[MiniMe4Eng]

And here is what ChatGPT is saying about it

Is it better for a dust collector to suck air through the filter or to push air through the filter
ChatGPT
For a dust collector, it is generally better to have the air flow in a configuration where it sucks air through the filter rather than pushing air through the filter. This configuration is commonly referred to as a "negative pressure" or "pull-through" system.

Here are a few reasons why sucking air through the filter is typically preferred:

[ol 1]
[li]Filtration Efficiency: Pulling air through the filter allows the filter media to effectively capture and trap dust particles, contaminants, and debris. The suction created by the dust collector helps ensure that the air passes through the filter media, maximizing filtration efficiency.[/li]

[li]Dust Containment: With a pull-through system, the filter acts as a barrier between the dust collection area and the exhaust or ambient environment. The negative pressure inside the dust collector helps contain the captured dust within the collector, reducing the risk of it escaping back into the working area or polluting the surrounding environment.[/li]

[li]Longer Filter Life: Pulling air through the filter tends to put less strain on the filter media compared to pushing air through it. This configuration can result in a longer filter life and reduced maintenance frequency, as the dust and debris accumulate on the outer surface of the filter, away from the clean side.[/li]

[li]Reduced Pressure Drop: In a pull-through system, the pressure drop across the filter is typically lower compared to a push-through system. This means the dust collector's fan doesn't need to work as hard, leading to potentially lower energy consumption and quieter operation.[/li]

[li]While a pull-through configuration is generally recommended, it's essential to follow the manufacturer's instructions and guidelines specific to your dust collector model. They can provide insights on the ideal airflow direction and any considerations unique to your equipment.[/li]
[/ol]

 

[LittleInch]

Hmmm,

Item 1 is rubbish
Item 2 has some legs. A negative pressure system will suck clean air in through any holes or gaps.
Item 3 is rubbish
Item 4 is rubbish
Item 5 is waffle.

A pull through system is much better for the fan but there is a higher negative pressure so collapse is a potential issue.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[LittleInch]

If you angle your inlet into that lower bin you'll create a bit of a cyclone filter....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[IRstuff]

Seems to me that ChatGPT is hallucinating again. The main reason I see for pull through is to NOT GET ALL THAT DUST IN YOUR PUMP. You can, if you want, but it'll increase the amount of maintenance and repair on your pump.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[MiniMe4Eng]

The advantage I see with a pullthrough setup is that if the blue container (filter housing) loses pressure it will suck clean air in at most
IF the system is a push through then dusty air will get out of the container through whatever weak points the filter housing has

Buying an off the shelf housing is not something that I want as I that type of housing is too tight and I want to be able to see inside
Ideally I should find a large transparent storage box that can cover the filter entirely and secure that against the top panner using a gasket

 

[LittleInch]

Also you might be able to blow the exhaust out of the work shop.... And not cover everything with fine dust.

But yes that's probably a good idea to pull air in rather than let it blow dust out

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Compositepro]

Be aware that fire and dust explosions can occur in dust collectors, Any hard shell containment can become a source of shrapnel as well as being another surface to clean. If you really want to direct the collector exhaust outside, place the collector outside, or place a larger plastic bag over the filter bag and duct that outside.

 

[MiniMe4Eng]

MOst of the workshops for hobbysts like me are set in a garage
Exhausting air outside will create negative pressure in a garage that does not have a lots of openings to get new fresh air in and it will create heating problems over the winter

 

[LittleInch]

Fair enough.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[hydtools]

As far as I know, garages are supposed to be ventilated so car exhaust will not collect. Or is that only for attached garages?

Fine dust will still be exhausted into the garage, whether push or pull without outside exhaust.

Ted

 

[MiniMe4Eng]

Many garages around here were built back duri the 60s and they do not fit the today shops. No ventilation was required back then

There is lots of first hand eperiences shared on line about this setup and it seems that even with an inverted floe these work great no dust