Microbes, Microns and Filters - some observations and recommendations about vacuum
cleaners
Take the humble vacuum cleaner, for example, which is the subject of this hopefully
informative article. Until recent years, it knew its place - in the cleaning cupboard.
Now, however, it has been virtually catapulted into the limelight as our number one
defender against the hordes of bacteria, mites and allergens that seem these days
to threaten to completely overwhelm us. It is a fact that increasing numbers of people
- particularly children - seem to be falling foul of conditions caused by atmospherically-carried
dusts, proteins and pollution in general. We are told that we must breathe pure,
clean air (no bad thing!) and that this or that system of vacuuming prowess will
ensure this.
I hope to be able, in the next few paragraphs, to be able to give a fair comparison
between the three basic systems that are in use in modern vacuum cleaners - the choice
is then yours. So where do we start? Well, in the beginning was -
1. The ‘traditional’ upright, tub or cylinder vacuum cleaner
This type of machine, which until recently comprised almost 100% of all sold, works
in a very simple way. At one end is a fan motor, (which creates the suction necessary
to provide the airflow needed) at the other end is a floor/upholstery/brush/crevice
tool which is connected to the machine by a hose. In the middle is a permeable paper
or fabric bag which allows air to pass through but traps the majority of dust and
dirt collected.
The style and specifications vary - some have rotating brushes, some don't - but
they all work the same way. If you have no problem with any allergic conditions,
this level of vacuum cleaner will almost certainly meet your needs. If you do have
allergy problems, then you’ll probably require a higher level of filtration in order
to trap the nasties. The most popular and most widely advertised method is to use
a machine with a HEPA high efficiency filter.
These filters will stop particles down to about 0.2 microns in diameter at a rate
of 99.997% retained soil. So what does that mean? Well, a micron is one millionth
of a metre - very small indeed! As comparison, a human hair is some 150 microns in
diameter and anything under 100 microns across is difficult to see with the naked
eye. These filters will retain 100% of dust at 0.5 micron diameter, 99.994% at 0.3
and 99.2 at 0.2. Under those diameters they don’t fall inside the test protocols
used by British Standards but by 0.1 micron you’re getting down to the size of some
of the bigger gas molecules anyway!
2. The whirlwind/cyclonic type vacuum cleaner
A recent (well, 1911 actually) arrival onto the mass market, these machines are a
step forward in that they do not use a collector bag and so are able to maintain
suction and airflow for longer periods, by utilising a 'whirlwind' effect that deposits
the larger particles in the bottom of the hopper or collection chamber.
They still use filters, though, as not all the dust can be trapped in the collection
chamber and these filters still have to be replaced fairly frequently, although on
some makes you can clean them out and reuse them. The effectiveness of the basic
models can be gauged by the fact that these machines are now, too, offered with optional
HEPA filter -indeed sometimes two filters!
Also, OK there’s no bag to buy but the collection chamber still has to emptied, with
all its attendant problems (slip and you’re back to square one - dust everywhere!).
They’re a step up from the first type but still fail to address fully the filter
blocking problem which restricts airflow and so reduces the machine's capacity to
clean. This also, by the way, causes the motor to work much harder and in extreme
instances to give up the struggle and fail completely.
Only by maintaining the airflow can the machine operate at peak efficiency and clogged
bags and /or filters simply will not allow this to happen. Is there any answer? Well,
only one I'm afraid - if you want to maintain the efficiency of your vacuum cleaner,
replace bags/empty the thing/make sure filters are not clogged. Sorry folks, but
that's it!
Now you may say we I have an interest in selling vacuum cleaners, so all this is
just sales talk. Well, frankly, the first part used to be true. I mean, that’s part
of what I did for a living. However, it made me look long and hard at how these machines
worked - so now you get the benefit, because I’m not selling you anything!
As for the second half of the statement - all that I can say is that it’s there to
help you, the customer, the one who will ultimately benefit from this information,
to make an informed decision as to which type of machine will best suit your needs.
If I’m guilty of that, so be it!
In this world of ever-increasing high-tech complexity you might be forgiven for thinking
that we are constantly having to employ more (and more complex) technology to achieve
our desired levels of hygiene. Every manufacturer of cleaning equipment and machines
is striving to reassure their customers that no effort is being spared in order to
protect you from attack by the generally nasty things that float around our homes.
As a basic rule of thumb, the more efficient a filter is, the more often it must
be changed or cleaned. And what a nasty job that is. Do it indoors and trapped dust
flies everywhere. Do it outdoors and it is inevitably raining/dark/the middle of
winter. Deep joy. However, I’m sorry, it has to be done. So - are there alternatives,
you ask? What about. -
So, it would seem that these filters are the answer. In fact they are if (you knew
there’d be an if, yes?) and only if the bags and filters are changed at what will
seem depressingly frequent intervals - and HEPA filters are not cheap.Why must this
be done? Well, to illustrate, suppose you’re having a meal that requires boiled rice,
lots of boiled rice. You drain it when cooked and put some into a sieve to rinse
the excess starchy stuff off. It works fine! So, in with the next lot. Hm - doesn’t
drain so quickly this time....next lot......this is really slow......last lot.......help!
the water won’t go through! Tip the rice out and you will see a horrible gludgy mess
- yes, the filter (sieve) is almost totally blocked! But, if you had cleaned the
sieve each time it would have worked perfectly! I think you can see the point (and
I don't mean clean rice with a vacuum cleaner, alright?).
