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224-G3 Issue E
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The I.O.M. Sampler*
IMPORTANT
The I.O.M. cassette and filter paper combined must be pre and post weighed together for an
accurate inhalable result
The I.O.M. sampler is designed and closely adheres to the definition for inhalable dust given in EN481
I.O.M. - what does it stand for? The "Institute of
Occupational Medicine". Based in Edinburgh,
researchers at the Institute developed this sampler to
overcome some of the difficulties encountered with
other sampling devices. It is less prone to the effects
of air movement around it than others and utilises a
cassette rather than just a filter paper. There is a very
good reason for the cassette system being adopted.
One of the problems with other devices using a filter
paper alone is loss of sample on the walls of the sampler
itself. The dust which coats the walls of the sampler is not
normally included in the results, hence under sampling
is a possibility. With the I.O.M. sampler this problem is
overcome by using a cassette with the filter inside. It is
important that when a sample is taken the cassette and
filter paper are pre and post weighed as a single unit. By
doing this all the dust on both the filter paper and on the
internal walls of the cassette are included.
The diagram below shows the component parts of the
sampler and how they are put together.
To fit a filter unscrew the front plate. The cassette,
comprising the inlet spout and filter support grid
can now be removed by pulling forward gently. The
two halves of the cassette clip together and can be
separated with gentle pressure. Once separated a filter
can be placed in the support grid. Snap the inlet spout
into the support grid making sure it is seated down
properly. The cassette is replaced into the body of the
sampler and the front plate screwed on firmly so that
all of the O ring seals are compressed, thus ensuring
there are no leaks.
For further information on the I.O.M. sampler see :-
1986 paper, “New Personal Sampler For Airborne Total
Dust In The Workplace” by D Mark / J Vincent. Ref:
Annals Occupational Hygiene No. 30 Pages 89-102.
The I.O.M. sampler can also be used for respirable
dust sampling by inserting a foam plug into the inlet
spout part of the cassette. The foam plug size selects
some of the dust that is drawn though it and allows
the correct type of dust to be collected on the filter.
It is also possible to measure both the inhalable and
respirable dust fractions in one sample using the foam
plug and I.O.M. cassette.
Dust Sampling - Inhalable and Respirable
Ref: Report IR/EXM/99/06 produced by the Health and Safety Laboratory (UK). Available on the HSE web site.
*Manufactured under license from the Institute of Occupational Medicine TM 2043339E.
Foam Plug
Cassette Inlet Spout
Cassette
Cap
Front
Plate
O Rings
Cassette
Inlet
Spout
Filter
Cassette
Support
Grid
O Ring*
Sampler
Body
Sealing Cap
Foam
Plug†
Spring
Clip
†Foam plug
only required for
respirable sampling
*Not required on
stainless steel
I.O.M. sampler
Rear view of front
plate showing
O ring positions
