Thread: HEPA filter for cleaning equipment

Just because the term HEPA (High Efficiency Particulate Arrestance) filter is used doesn't necessarily make it a better filter than other type of filters.
Forget the name HEPA and instead look at the "filter efficiency" (% of dust removed from an air stream) and the "micron rating"

A basic hospital HEPA air filter has between 99.9 and 99.97% efficiency for particles of 0.3 microns or bigger.

This is a HEPA filter I have in my room filter unit in my shed.
Its rating 99.99% at 0.3 microns.
These filters go down to 99.9997% and beyond that it becomes near impossible to measure.

HepaSpecs.jpg

The unit itself is designed for clean air laboratories and looks like this
Its super quiet and draws about 80W of power.
Hepa1.jpg

This unit cost US$700 in 2002 when they they were more than AUS $1500 but I would not bother using them in a house.
Instead I would try and make the house as dust and bug free as possible.

Move house so you are away from dust sources like busy streets and building sites
No carpets - these are the single worst thing for dust.
No pets - we have two fluffy dogs.
Mimimise the use of exposed fabrics - SWMBO is a rabid sewer and there are pieces of fabric everywhere.
Keep the house clean - use an eco cleaning fluid or even just hot water or steam.
Even some so called HEPA vacuum cleaners can make the house air dirtier than it started with.
Better quality vacuums will stir up dust ie the motor cooling loop will fluff dust up off surfaces into the air.
However most vacuums will usually pick up more dust than they stir up and eventually as the fluffed up dust settles there will be less dust in the air.
Shower regularly, the human body sheds ~100,000 particles of skin an hour so wash clothing and bedding regularly.

I have a fine dust monitor running continuously inside and outside my house and the only time I see the dust levels go anywhere close to a problem is the couple of days a year when there are bushfires burning off in the Perth hills and the wind blows towards the city. (currently the reading inside the house oscillates between 7 and 4 ppb Conc PM10)

Perth already has very low dust levels anyway with a yearly average (17 ppb) which is low for any city. Remote areas like mountains, forests etc have around 4 ppb, (Beijing is around 200 ppb and some places in india are over 400 ppb). Inside our house is usually less than the air outside especially when there are bushfires which. This is normal for most situations is why the authorities recommend staying indoors when there is a dust problem outside. The small amount of dust that will enter a house will soon drop out of the air with 0.3-0.5 micron dust has a half residence time of about 25 minutes.

Generally most dust in a house is generated inside the house itself.
If you live in a dusty area the trade off is to ensure enough fresh air comes into the house without letting too much dust into the house.