Hepa filter for new model CTL Midi in UK

[AlexThePalex]

Err, shall we just put that in a big box marked Not My Problem?

Maybe, but perhaps it might fit better in that big box marked Not My Solution.

 

[Simon O]

Do you use a particulate meter to measure air quality in your shop or jobsite .

Have you tested the difference the HEPA filter makes (if any) ?

I think what some of us are saying is that the HEPA filter doesn't make much of a real world difference in air quality five feet away from the extractor because it's only part of the overall system.  We're also saying that a bigger factor in the overall air quality is the inability to capture all the dust at the source. And it's that dust which doesn't go through a filter at all; that contRibutes more to the air qualty than whether your secondary filter stops .3 or 1 micron particles.

I'm coming over next week, maybe I can bring you some HEPA filters if you can't find someone on Amazon or eBay to ship them to you direct.

Thanks for your summary [member=67935]xedos[/member], I guess my central point is that the standard filters are Not designed to catch the smaller particles (less than 1 micron), so my concern is that these invisible smaller particles are then exhausted into the workplace, turning my extractor into a distributor rather than a gatherer - this is what I'm attempting to minimise by installing a Hepa filter.

I do see the point you raise about the inability to capture all dust at the source, although-
1.I'd be curious to know on what you base the assertion that this is the 'bigger factor'? By what margin? and
2. All I'm trying to do is optimise the effectiveness of the extractor, with the parts that are available to me, it's self evident that this is never going to be 100% capture.
The suggestion overall here is that installing a Hepa filter makes an insignificant difference to the dust in the air - again as far as I know there are no test results for this?

The only independent and rigorous testing of extractors efficiency that I know of  are those conducted by the TNO in the Netherlands, and they don't give those sorts of statistics.
I'm assuming when OSHA introduced the new requirements governing respirable silica dust in June 2017, they did this on the back of some independent testing, which would have included looking at the effectiveness of different types of filters? Perhaps there's some data that's available there? It'd certainly be useful to see what they based their decisions on making (for certain tasks) Hepa filters mandatory, and for other tasks Hepa filters strongly recommended.

I'm not sure whether any tests I could conduct on a work site, would have any validity - the TNO testing procedures are ones I definitely could not replicate, but I guess there'd be no harm in setting something up at work, using a particulate sensor.

And thanks for your kind offer, I tried a tool company in Canada (as couldn't find one in the US that said it would ship to UK) but apparently Festool prohibits them selling outside Canada. My partner's brother is coming to UK from Seattle, in February next year, so I'll ask him to bring a couple over.

 

[AlexThePalex]

I do see the point you raise about the inability to capture all dust at the source, although-
1.I'd be curious to know on what you base the assertion that this is the 'bigger factor'? By what margin? and
2. All I'm trying to do is optimise the effectiveness of the extractor, with the parts that are available to me, it's self evident that this is never going to be 100% capture.
The suggestion overall here is that installing a Hepa filter makes an insignificant difference to the dust in the air - again as far as I know there are no test results for this?

Just go do some sanding. Or sawing. On whatever object, you will find that even though you are using an extractor there is always residual dust at the place where you are working. Some of the dust you generate and is not captured by the vac falls directly down, and some of it is spewed into the air. Depending on what you're working on, the amount of residual dust can be very small, or very large.

But still, if there is dust you can see with your own eyes, it means it is a lot more than those particles that go through the filter, because those are so small you can't even see them.

 

[Simon O]

I do see the point you raise about the inability to capture all dust at the source, although-
1.I'd be curious to know on what you base the assertion that this is the 'bigger factor'? By what margin? and
2. All I'm trying to do is optimise the effectiveness of the extractor, with the parts that are available to me, it's self evident that this is never going to be 100% capture.
The suggestion overall here is that installing a Hepa filter makes an insignificant difference to the dust in the air - again as far as I know there are no test results for this?

Just go do some sanding. Or sawing. On whatever object, you will find that even though you are using an extractor there is always residual dust at the place where you are working. Some of the dust you generate and is not captured by the vac falls directly down, and some of it is spewed into the air. Depending on what you're working on, the amount of residual dust can be very small, or very large.

But still, if there is dust you can see with your own eyes, it means it is a lot more than those particles that go through the filter, because those are so small you can't even see them.

Thanks so much Alex I'll take your advice and go do some sanding and sawing on objects, then use my eyes to see the dust that the extractor does not capture - dust which ..... you know what, I give up - we're either talking at cross purposes, or you have not understood a word I've been saying. So let's just agree that we have different opinions and leave it at that.
I'm happy to pay for Hepa filters for my Midi and to be using Hepa filters in my Starmix, presumably your happy with whatever you use - good luck.

 

[AlexThePalex]

you know what, I give up - we're either talking at cross purposes, or you have not understood a word I've been saying. So let's just agree that we have different opinions and leave it at that.

I didn't even know there was a difference of opinion here. Or a DISCUSSION at all.

In your quote I reacted to I see no statement of opinion at all from your side, just a question. You don't like people to attempt to answer it? Then I'd advise you don't ask them.

Fine, leave it at that.  [huh]

 

[xedos]

1.I'd be curious to know on what you base the assertion that this is the 'bigger factor'? By what margin? 

I haven't conducted any scientific, quantifiable measurements.  I can see what is not captured by the system while sanding at my station and the dust in the secondary air cleaners nearby.  Both are significant enough to see.  Which means the little bit xtra the HEPA filter captures is really meaningless.

I'm not sure whether any tests I could conduct on a work site, would have any validity

  Then what would be the real point of the better filter except as a placebo ?  In the OSHA rule , the government is mandating the performance measurement and levying fines for non compliance.  This would be a tangible reason to have the better filter.    Even with the HEPA filter I think PPE is still required , which should tell you something about the system right there.

At the end of the day (mine anyway) it's a zero sum game. Lets say the smallest particle I produce is .3 microns and my CTwhatever captures 100% of those with the HEPA filter.  Great.  What happens to all the of the particles of any size that are not sucked up by the vacuum ?  They go airborne and flow to........... For woodworking tasks I just don't lose sleep over whether my filter is 1 or .3 micron efficient.

If I were sanding or cutting material with asbestos, lead, formaldehyde, or mold - I would err on the side of caution.

 

[FestitaMakool]

If concerned, there are fresh air filtered masks, or powered respirator, that constantly flows fresh filtered air over the users face, covering your whole face. It might be an healthy alternative, even with a DC with HEPA, as the mask will protect you from what the DC doesn’t extract from the work area, and even more.

 

[Michael Kellough]

Xedos said  “If I were sanding or cutting material with asbestos, lead, formaldehyde, or mold - I would err on the side of caution.”

Add silica to the list. An industrial chemist told me, “Clinically, there is no difference between asbestosis and silicosis”. In both cases the lung tissue is equally ruined, it’s just caused by different materials. Seems to me, in general, people are overly concern about asbestos and not not concerned enough about fiberglass.

 

[Michael Kellough]

The irony of adding finer filtration to the vacuum is that less dust will be collected.

 

[Gregor]

The irony of adding finer filtration to the vacuum is that less dust will be collected.

Only in case the additional finer filtration reduces airflow, something that can be avoided by adding the fine filter behind the motor (instead of infront of it).

Apart from that it's a general good idea to not inhale particles that can't be exhaled again (as you're unable to cough them out), hence to use HEPA. And to use a laser beam to check for presence of floating fine dust, check if the air cleaning setup might be in need of an upgrade...

 

[Michael Kellough]

The irony of adding finer filtration to the vacuum is that less dust will be collected.

Only in case the additional finer filtration reduces airflow, something that can be avoided by adding the fine filter behind the motor (instead of infront of it).

Apart from that it's a general good idea to not inhale particles that can't be exhaled again (as you're unable to cough them out), hence to use HEPA. And to use a laser beam to check for presence of floating fine dust, check if the air cleaning setup might be in need of an upgrade...

I’m not convinced the location of the flow inhibitor (fine filter) in a closed system makes a difference. And the system (from the point of intake to output of the vacuum itself) has to be closed doesn’t it?

 

[Gregor]

I’m not convinced the location of the flow inhibitor (fine filter) in a closed system makes a difference.

A filter being between intake and motor can be exposed to a maximum of 1 atmosphere pressure differential (given the motor creating a perfect and instant vacuum and no other resistances except the filter exists). But a filter between the motor and the outlet can be exposed to a (way) higher pressure differential (if needed multiple atmospheres) without, given the motor being up to it, reducing the vacuum that is created at the inlet - and the higher the vacuum at the inlet (relative to the room) the better the extraction.

Thus it's a good idea to put all filters that are not directly needed to protect the device itself between the motor and the outlet.

 

[AlexThePalex]

I think you're on to something! I'm going to modify my Minis to have a normal filter before the motor and a HEPA filter behind it.

Boy, you guys gonna be so jealous at how healthy I'm gonna be now!  [big grin]

 

[xedos]

Be careful the back pressure on the exhaust does not shorten your turbine's life.

 

[FestitaMakool]

Isn’t HEPA filters placed on exhaust side of the turbine/motor?

 

[Gregor]

Isn’t HEPA filters placed on exhaust side of the turbine/motor?

Yes.

At least on the ones that deconstructed in front of me...

 

[FestitaMakool]

[big grin] [big grin]
..As I vaguely remember my last domestic dust collector with HEPA did as well..
It had big gaps around the filter, so I eventually just “misplaced” it.
But, the motor ran much cooler afterwards, it had scary hot exhaust with the filter in place, I was afraid of it igniting dust  [blink]. Not a good feeling putting it to storage in a closed cabinet without cooling first.