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View Full Version : Jet Air Cleaner sizing question



Larry Browning
03-28-2008, 7:39 PM
I am considering spending my tax rebate money on this (http://www.amazon.com/708620B-AFS-1000B-Filtration-Electrostatic-Pre-Filter/dp/B00004R9LO/ref=pd_bbs_sr_1?ie=UTF8&s=hi&qid=1206746943&sr=8-1#productDetails)

However, I am wonder if one is going to be enough. My main shop is 30X30X9 I had outlets put in the ceiling for just this purpose in 2 places thinking I would put in 2. How do I figure this? I know I have 8100cf but how do I tell how big of an air cleaner I need to properly clean my air?

jason lambert
03-28-2008, 10:04 PM
I have that air cleaner in my 24X24 shop and it is more than enought to move the air. But I am also putting in a huge onida dust collection system so there is not all that much air born dust. I do not know how much you have floating around or how high the celing is. I think it has enought power but I do not know how often you would have to change the filters and how much do you work in your shop is it a hobbie or full time?

I have had mind for about 3 months work on weekends and my filters are still not near cleaning.

Brad Hammond
03-28-2008, 10:52 PM
i've had that cleaner for 3-4yrs now and it's done a great job. my shop is 36x36x10. should do just peachy!! that thing really moves alot of air! you'll be very happy.

Jason Beam
03-28-2008, 11:00 PM
The general range is that you want something to cycle the air at least 6 times per hour, 8 is better and 10 is GREAT ... think of the time - 6 per hour means every ten minutes... pretty nifty.

Take your cubic feet of air divided by the CFM of the machine and that's how many times you can get it to clean your air AT BEST ... so the numbers should be like 8-12 times to get within that 6-10 range, methinks.

Carl Fox
03-29-2008, 3:08 AM
I'm really glad, because I just ordered 1 today! That exact model.:D

Ken Harrod
03-29-2008, 8:19 AM
The general range is that you want something to cycle the air at least 6 times per hour, 8 is better and 10 is GREAT ... think of the time - 6 per hour means every ten minutes... pretty nifty.

Take your cubic feet of air divided by the CFM of the machine and that's how many times you can get it to clean your air AT BEST ... so the numbers should be like 8-12 times to get within that 6-10 range, methinks.

You math is a little off.

Cubic Feet of shop / CFM of Machine = how many minutes to turn over the air 1 time.

CFM of Machine * 60 / CF of Shop = how many times air is turned over per hour.

Jason Beam
03-29-2008, 2:44 PM
Doh' ... thanks for catching that, Ken.

jason lambert
03-29-2008, 2:56 PM
One thing I can say is on high it is pretty loud, the bigger one on low might be quieter and move more air. But I would think it is big enought, just another thing to consider but I am a stickler for noise since my shop is in the house.

Peter Quadarella
03-29-2008, 7:50 PM
The sound is the only thing stopping me from buying one of these. I'm not sure I want to have a constant loud noise the whole time I am in the shop. Are there any out there that are not a bother?

Jason Beam
03-29-2008, 9:48 PM
On low, the jet isn't THAT loud ... easily talked over at a normal speaking volume - especially if it's up a ways. Hardly louder than an old fridge, i'd say.

Carl Fox
03-29-2008, 11:37 PM
On low, the jet isn't THAT loud ... easily talked over at a normal speaking volume - especially if it's up a ways. Hardly louder than an old fridge, i'd say.

I imagine a little soundboard would go a long way...

Paul Stroik
03-30-2008, 8:44 AM
Larry...I have the JDS 2000 Air-Tech 750 model in my 24 x 32 sq. ft. shop. Have had it for 7 years and wouldn't be without it. Just recently realized I have never changed the secondary filter:eek:. So quiet I forget it's there. Placed the order yesterday. Best of my recollection - this size was supposed to be sufficient for my size shop.Money well spent in my opinion.
I keep mine on low-medium, plugged into a ceiling outlet controlled by the main light switch so it is always on when I'm in the shop.

Wilbur Pan
03-30-2008, 10:00 AM
I know that conventional wisdom says that that for air cleaners you should have enough CFM to exchange the room volume of air 6 times an hour or so. I went for 25 exchanges per hour. You'll clear out the airborne dust much more quickly, and it's easy to get there -- just add more air cleaners.

If you work through the math, if your air cleaner is about 75% efficient (a conservative estimate), at the usual 6 air exchanges per hour, it takes 2 hours and 10 minutes to reduce airborne dust to less than 1% of the original level.

If you shoot for 25 or so air exchanges per hour (which isn't hard: my 11'x20' shop has 1760 cubic feet, my JDS air cleaner is rated at 750 CFM, which works out to 25 exchanges per hour), it takes 16.4 minutes to reduce airborne dust to less than 1% of the original level.

Also, keep in mind that the CFM rating for air cleaners is often made without the filters in place, and that the real world CFM is probably less. JDS rates their air cleaners with filters in place, so their specs are more reflective of what you'll get.

Ken Ganshirt
03-30-2008, 12:18 PM
Wilbur has a good point. But there are a couple of issues still missing from this, and almost every, discussion about air cleaners.

First is the myth that you can simply divide the cubic foot volume of the shop by the cubic feet per minute rated airflow of the cleaner to figure out how long it will take to run all of the shop air through the cleaner.

The true answer is, you will never run all the shop air through the air cleaner. Not long after you turn your air cleaner on, a relatively fixed circulation pattern will develop. The air within that circulation pattern will be cycled through the air cleaner over and over. The air outside that circulation pattern will not be cycled through the cleaner. This is a gross simplification because there will be some turbulence along the edges of the circulation pattern that will cause some air in the flow to be "dropped" and some outside the flow to be "captured", but there will be areas of the shop where the air will be completely unaffected by the circulation pattern of the air cleaner.

The second issue is what your air cleaner is actually cleaning out of the air? If the filter is 1 micron, you aren't filtering anything smaller ... most of the respirable particles (the particles that will get through the defenses in the upper airway and down into the lungs to do the longer term damage) are smaller than 1 micron.

It's irrelevant how well the filter is filtering if all it's filtering are particles larger than the ones of most concern.

...ken...

glenn bradley
03-30-2008, 12:25 PM
30x30x9 = 8100 cubic feet.
Jet moves 1044 CFM.
Moves the volume of your shop every 7 hours (less some for filter resistance and all that).

I have two units (1150 and 1600 CFM, IIRC) in a 20x30x9. I only run both during a known messy activity (routing MDF for example). Normally the 1150 does fine for general off and on sawing, sanding, etc.

Wilbur Pan
03-30-2008, 1:35 PM
Ken brings up some excellent points. There's an easy way to get around the "racetrack of air" phenomenon: set up an oscillating fan. I have one in the corner of my shop that is opposite to where the air cleaner is hanging, and I aim it in the general direction of the air cleaner. With the oscillating motion, the air gets mixed more efficiently than if the air cleaner was operating solo. If you have two air cleaners, you can set them up so that they disrupt each other's "racetrack".

As to the 1 micron issue: I know that the JDS filters are rated down to 1 micron. A HEPA filter would be even better. When I was searching for air cleaners, I couldn't find any that had true HEPA filters that were also suitable for a workshop environment. But it's better than not having an air cleaner at all.

Ken Harrod
03-30-2008, 4:38 PM
30x30x9 = 8100 cubic feet.
Jet moves 1044 CFM.
Moves the volume of your shop every 7 hours (less some for filter resistance and all that).

I have two units (1150 and 1600 CFM, IIRC) in a 20x30x9. I only run both during a known messy activity (routing MDF for example). Normally the 1150 does fine for general off and on sawing, sanding, etc.

CFM = Cubic Feet per MINUTE. So, it moved the air volume in that shop every 7 MINTUES, not HOURS.

Ken Ganshirt
03-31-2008, 1:05 PM
As to the 1 micron issue: I know that the JDS filters are rated down to 1 micron. A HEPA filter would be even better. When I was searching for air cleaners, I couldn't find any that had true HEPA filters that were also suitable for a workshop environment. But it's better than not having an air cleaner at all.
Hi Wilbur,

I'm new here so I need to say that I ask the following questions with the utmost respect intended and not as derogatory comments. I'm not a professional writer so I don't know how to ask such questions other than straight out.

Is that true? If your air cleaner is not filtering out the particles that will do the most damage to your lungs, is it really worthwhile? Or is it a waste of money? Or is it even worse: a serious danger because we think it's actually doing some good and don't take other precautions?

Perhaps I should ask the question a different way. If the air cleaner is not filtering any of the respirable particles, in what way do you think it is better than not having an air cleaner? (Other than the obvious fact that the horizontal surfaces in the shop will be a little less dusty.)

...ken...

Wilbur Pan
03-31-2008, 1:52 PM
Hi Ken,

Overall, respirable dust is dust particles that are about 5 microns and below. It is true that a 1 micron filter won't get all the respirable dust, as it will not filter particles smaller than 1 micron very effectively. But it will take out the 1-5 micron dust, which, as I said, is better than nothing.

I have never regretted getting my air cleaner, even though it is rated for 1 micron particles. For dust-intense activities, such as sanding, I'll also put on a respirator with a P100 filter.

Larry Browning
03-31-2008, 3:04 PM
I did not get one of these air cleaners at the same time as I got my Gorilla because it was my understanding that if I did a good job of installing and using the dust collecting system I had, the air cleaner would be unnecessary or of marginal value. Collecting dust at its source is by far the best way to go. However, reality has proven different for me. I have not fully implemented all the dust hoods such as I still do not have a blade guard dust collection solution even though I really should. I also have come to the realization that hooking up the DC system to every little thing that produces dust is not practical for me. I don't have the personal discipline to ever do this ALL the time. I still have plans of building a sanding table that includes dust collection, but finding a practical way to collect dust from a hand held router, drill, circular saw and sanders on large bulky pieces will always be unachieved in my shop. So I think the air cleaner is something that would really help me.
I think I have decided to get 2 units base on this thread. I know it can't hurt, (pretty sure it won't suck the paint off the walls) and it looks like I could probably run them on med or even low to cut down on the noise a bit and still have plenty of filtration..

Ken Ganshirt
03-31-2008, 3:18 PM
Hi Larry,

My question wasn't whether or not an air cleaner might be useful. My question was whether or not an air cleaner that will not filter anything finer than 1 micron might be useful. I've decided it won't be for me ... well, actually, I've decided it's not worth the money. No business case. Too little incremental value for the cost.

But that's in the context that I've just discovered purely by accident that my small dust collector is currently functioning as a good air cleaner. As I've mentioned in another thread, measurements with my Dylos particle counter show that it will clean the shop air of particles at least as fine as 0.5 microns almost completely in two to three hours of operation.

...ken...

Eric Gustafson
03-31-2008, 4:36 PM
While I know that the filter is rated for 1 micron, in practice, it works much better. I have the Dylos .5/2.5 micron particle counter and we tested it and the Jet air filter in my BIL's shop. His shop is quite small, as it is only 10' x 20'. We would do some sanding and watch the particle counter (on the .5 scale) skyrocket. If we did not turn on the air cleaner, that value would hold very well. But with the cleaner turned on the particle count dropped quickly. Within 20 minutes the count had dropped to acceptable levels.

My guess is that enough dust gets trapped in the filter that it actually traps particles smaller than 1 micron.

Ken Ganshirt
03-31-2008, 10:11 PM
Hi Eric,

That's good feedback. So far the only 1 micron things I have experience with are the 1 micron filter bags on my dust collectors. My old King has a pretty good cake in it and filters the fines really well (according to my Dylos 0.5/5 micron counter). It can actually pull the fine particle count down into the single digit range in my 31 x 17 x 10 shop.

My new Delta has a brand new 1 micron bag on it and all it does is pump the fine stuff around the shop.

With the fine count sitting at around 500 on the metre display for a start, I can turn on the Delta with its spiffy clean 1 micron bag and it will be up to 3500 - 4000 in 10 minutes. That's with no other activity in the shop. It's super at sucking up the existing settled dust and recirculating it. If I can figure out how to get it filtering better it will make a really great air cleaner.

With the fine count sitting at over 12000 (yes, that's three zeros) after using the random orbital sander for a bit the King with its caked up 1 micron bag pulled the count down to a stable 45 in two hours.

Perhaps the answer for the Delta is to use it to suck the stuff out of the filter bag on the King and get a good cake going on it, as someone suggested.

Has the filter on your brother-in-law's air cleaner been used for awhile and is filtering better than when it was brand new?

...ken...

Peter Quadarella
03-31-2008, 11:04 PM
A cyclone might help with the Delta also.

Ken Ganshirt
04-01-2008, 12:45 AM
A cyclone might help with the Delta also.
I'm not sure I understand your suggestion, Peter. The Delta is a single-stage dust collector. A cyclone is a completely different type of dust collector. I'm not sure how the two relate in your suggestion. :confused:

...ken...

Eric Gustafson
04-01-2008, 2:08 AM
Has the filter on your brother-in-law's air cleaner been used for awhile and is filtering better than when it was brand new?

...ken...

Hi Ken,

The filter has seen quite a bit of use. He also has a Jet dust collecter. I bought a Clearvue but have no data on that yet. The Jet has the large pleated filter on top and the bag below. It also does a great job at lowering the particle count and compared to the power of the Cleavue it seems like a dog to me. I was completely surprised by how well the Jet DC works. Unfortunately, I did not get the Dylos until after both filters had seen a lot of use, so I have no baseline.

Peter Quadarella
04-01-2008, 10:23 AM
What I meant is, it should be possible to attach the collector through a cyclone body. Similar to what people do with shopvacs and the mini cyclones (e.g. mini cv06). If you look at clearvue's site, they sell the body only (cv1400 or cv1800) for about $400.

Quesne Ouaques
04-01-2008, 2:07 PM
I have the Penn State AC-1000, which looks identical to the Jet. It has all of the same specs, though I don't really know if they are directly comparable.

http://www.pennstateind.com/store/ac1000.html

My shop is smaller than yours (30' x 15') so I don't know how relevant my comments will be, but I will say that the unit is extremely effective in moving and filtering the air in my shop. If they are, in fact, the same AC with different paint jobs, then I can also tell you that it is a quality unit; strong and very well made.

Ken Ganshirt
04-01-2008, 6:06 PM
What I meant is, it should be possible to attach the collector through a cyclone body. Similar to what people do with shopvacs and the mini cyclones (e.g. mini cv06). If you look at clearvue's site, they sell the body only (cv1400 or cv1800) for about $400.
Thanks for the clarification, Peter. How would that help the filtering issue that I raised? Eg. the 1 micron bag on my new Delta dust collector doesn't filter the fine stuff very well at this point and mostly just recirculates it according to my measurements with the Dylos air quality monitor. I was pretty much focused on improved filtering on the dust collector itself. How would turning the dust collector into a two-stage unit (adding the cyclone body in front of the DC) help with filtering that really fine stuff (0.5 to 5 microns)?

...ken...

Peter Quadarella
04-01-2008, 10:41 PM
From using the mini cyclone, it really seems as though very little of the stuff that gets sucked up ends up going through the filter. I don't have a meter to check though, so maybe it's only saving the bigger stuff, but I have to think with it stopping 99.9% of the big stuff, at least some of the little stuff is getting stopped also. It would be nice if one of the folks with a Dylos could check this out.