My vacuum cleaner does not have a HEPA filter and I would like to get
a cleaner that does.

Can someone who understands the physics of HEPA filtration help me
understand HEPA a bit better please. Google is not much of a friend
for this info!

-----

Is HEPA a registered trademark?

What technology does a HEPA filter make use of? Is it nothing much
more impressive than a very fine aperture standard filter?

is the HEPA filter on a vacuum cleaner likely to need replacing more
often than non-HEPA on account of the greater dust it traps?

Can a HEPA filter be washed or otherwise cleaned so that it can be
reused? Or is the life of a HEPA filter so long that this is not a
consideration.

------

Thank you for any info.

Will wrote:
My vacuum cleaner does not have a HEPA filter and I would like to get
a cleaner that does.

Can someone who understands the physics of HEPA filtration help me
understand HEPA a bit better please. Google is not much of a friend
for this info!


I'm curious - if you don't actually know what HEPA is, why do you
believe you need/want it?

http://en.wikipedia.org/wiki/HEPA
http://www.eh.doe.gov/hepa/index.html


--
Grunff

Will wrote:
My vacuum cleaner does not have a HEPA filter and I would like to get
a cleaner that does.

Can someone who understands the physics of HEPA filtration help me
understand HEPA a bit better please. Google is not much of a friend
for this info!


From Google: http://www.eh.doe.gov/hepa/

Dear Will:

"Will" wrote in message
...
My vacuum cleaner does not have a HEPA filter and I
would like to get a cleaner that does.

You like the benefit of efficient particle removal of a certain
size (or larger), and you are willing to pay more for the bags,
buy more of them, and change them more frequently.

Can someone who understands the physics of HEPA
filtration help me understand HEPA a bit better please.
Google is not much of a friend for this info!

-----

Is HEPA a registered trademark?

No, but it is a recognized standard acronym.

What technology does a HEPA filter make use of?
Is it nothing much more impressive than a very
fine aperture standard filter?

Correct. Yet there are small modifications that can be made to
the element to extend service life... by a few minutes.

is the HEPA filter on a vacuum cleaner likely to
need replacing more often than non-HEPA on
account of the greater dust it traps?

Not "greater dust". It has a small pore size, and using it means
blocking the small pores will block all flow.

Can a HEPA filter be washed or otherwise
cleaned so that it can be reused?

Possible, but not likely. Water carries contaminants, and these
contaminants scale out and block small pores.

Or is the life of a HEPA filter so long that this
is not a consideration.

Anything one could do to extend bag life, or reduce the number of
bags used per annum would be a sales feature. But then, once you
buy the vacuum cleaner, they have hooked you for replacement
bags. Just like ink jet printers...

Thank you for any info.

You have good links by the others.

David A. Smith

Will wrote:

Is HEPA a registered trademark?

It may have become one, although it started life simply as an acronym.

What technology does a HEPA filter make use of? Is it nothing much
more impressive than a very fine aperture standard filter?

It ii a fiberous mat - when talking about stanad alone filters ifusually
with a large surface area enclosed in a container of some sort

is the HEPA filter on a vacuum cleaner likely to need replacing more
often than non-HEPA on account of the greater dust it traps?

The HEPA filter is usually the last filter in a sequence and hce is fed
mostly clean air. It will trap the smallest and most penetrating
particles including the carbon dust generated by the motor itself.

Can a HEPA filter be washed or otherwise cleaned so that it can be
reused?

Not IME.

Or is the life of a HEPA filter so long that this is not a
consideration.

They last a reasonable time if you avoid things like sucking up plaster
dust (or any other super fine clogging material)



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Will wrote:
My vacuum cleaner does not have a HEPA filter and I would like to get
a cleaner that does.

Why?

Can someone who understands the physics of HEPA filtration help me
understand HEPA a bit better please. Google is not much of a friend
for this info!

HEPA stands for High Efficency Particulate Air. It's simply a finer mesh so
it traps smaller particles, typically 99.95% efficient in removing particles
down to 0.3 micron. A human hair by comparison has a diameter of 60 -90
micron.

Is HEPA a registered trademark?

Not as far as I know, more an internationally agreed performance standard.
Vacs for asbestos work to similar standards.

is the HEPA filter on a vacuum cleaner likely to need replacing more
often than non-HEPA on account of the greater dust it traps?

Yes sort of. HEPA's are more commonly found as final exhaust filters, the
main filters trap the majority of the dust, leaving the HEPA to filter only
the finer particles.

Can a HEPA filter be washed or otherwise cleaned so that it can be
reused? Or is the life of a HEPA filter so long that this is not a
consideration.

You can't wash then, but they last a reasonable time (see above).

Considerable benefits if you suffer from asthma, but they also reduce
airbourne dust to almost zero, so you don't have to dust so often.

--
Dave
The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257

On 03 Apr 2006, wrote:

Will wrote:
My vacuum cleaner does not have a HEPA filter and I would like
to get a cleaner that does.

Can someone who understands the physics of HEPA filtration help
me understand HEPA a bit better please. Google is not much of
a friend for this info!


I'm curious - if you don't actually know what HEPA is, why do
you believe you need/want it?

http://en.wikipedia.org/wiki/HEPA
http://www.eh.doe.gov/hepa/index.html



Then you haven't smelt the dust which blows up when I hoover using my
current vaccuum cleaner!

On 03 Apr 2006, Sam wrote:

Will wrote:
My vacuum cleaner does not have a HEPA filter and I would like
to get a cleaner that does.

Can someone who understands the physics of HEPA filtration help
me understand HEPA a bit better please. Google is not much of
a friend for this info!


From Google: http://www.eh.doe.gov/hepa/


I got that far with Google but the site is full of heavy duty topics
all of which seem to assume the reader knows the basics of HEPA. I
couldn't find an intro or FAQ or primer there so then I posted to the
newsgroup.

Replying to myself ...

I asked here about HEPA and from the replies it seems that maybe I
could get some HEPA standard filter material and cut it to shape to
fit the final exhaust grille on my existing hoover. If air flow is
badly impeded by this then I could remove the original filter
material.

Q1) Assuming here are no other significant outlet vents on the hoover
then would this work in reducing airborne dust?

Q2) Does air passing through a HEPA filter get slowed down more than
it would when passing through a conventional filter? (Assuming all
other things like area covered is the same.)

Dear Will:

"Will" wrote in message
...
....
If air flow is
badly impeded by this

It will be.

then I could remove the original filter
material.

Then the "muck" you vaccum up will build up on the fins of the
"fan", changing its dynamic charateristics, and ultimately
causing it to fail. This is a bad thing. Instead, increase the
surface area of the external "bag".

Q1) Assuming here are no other significant outlet
vents on the hoover then would this work in reducing
airborne dust?

Yes.

Q2) Does air passing through a HEPA filter get
slowed down more than it would when passing
through a conventional filter? (Assuming all
other things like area covered is the same.)

Likely the answer to your question is "no". Because you are
trying to push that same volume of gas+ through a smaller total
orifice, so the average speed must go up.

Also, some blower motors are cooled by the exit air stream. So
be *sure* you do not constrict this airflow for long...

David A. Smith

"The Medway Handyman" wrote in message
. uk...
Will wrote:
My vacuum cleaner does not have a HEPA filter and I would like to get
a cleaner that does.

Why?

Can someone who understands the physics of HEPA filtration help me
understand HEPA a bit better please. Google is not much of a friend
for this info!

HEPA stands for High Efficency Particulate Air. It's simply a finer mesh
so it traps smaller particles, typically 99.95% efficient in removing
particles down to 0.3 micron. A human hair by comparison has a diameter
of 60 -90 micron.

Is HEPA a registered trademark?

Not as far as I know, more an internationally agreed performance standard.
Vacs for asbestos work to similar standards.

is the HEPA filter on a vacuum cleaner likely to need replacing more
often than non-HEPA on account of the greater dust it traps?

Yes sort of. HEPA's are more commonly found as final exhaust filters, the
main filters trap the majority of the dust, leaving the HEPA to filter
only the finer particles.

Can a HEPA filter be washed or otherwise cleaned so that it can be
reused? Or is the life of a HEPA filter so long that this is not a
consideration.

You can't wash then, but they last a reasonable time (see above).


Never say never (or can't)!

The Dyson range includes some which have a 'Lifetime HEPA' filter in the
exhaust air stream. The filter is intended to be hand-washed. It seems to be
composed of a foam, which for what it's worth it's blue and 'squidgy'. Dyson
recommends that the filter is washed 'at least every six months' and it
should be air-dried (they recommend placing it under a radiator). Spare
filter assemblies ( a yellow plastic cage containing the blue foam filter)
are purchasable - (most folk keep one spare and one in use). I exchange the
filter about every six months (honest ) ... the filter is quite black when I
get araound to exchanging it and requires vigorous squeezing to restore it
to its natural blue colour.


Considerable benefits if you suffer from asthma, but they also reduce
airbourne dust to almost zero, so you don't have to dust so often.

--
Dave
The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257

--

Brian

On 03 Apr 2006, John wrote:

Will wrote:

Is HEPA a registered trademark?

It may have become one, although it started life simply as an
acronym.

What technology does a HEPA filter make use of? Is it nothing
much more impressive than a very fine aperture standard filter?

It ii a fiberous mat - when talking about stanad alone filters
ifusually with a large surface area enclosed in a container of
some sort

is the HEPA filter on a vacuum cleaner likely to need replacing
more often than non-HEPA on account of the greater dust it
traps?

The HEPA filter is usually the last filter in a sequence and hce
is fed mostly clean air. It will trap the smallest and most
penetrating particles including the carbon dust generated by the
motor itself.

Can a HEPA filter be washed or otherwise cleaned so that it can
be reused?

Not IME.

Or is the life of a HEPA filter so long that this is not a
consideration.

They last a reasonable time if you avoid things like sucking up
plaster dust (or any other super fine clogging material)



Can I buy generic HEPA filtration material in the form of a sheet?