SKC 224-PCMTX8 Step-by-step Manual

www.skcltd.com

Step by Step Guide

An Introduction to Air Sampling

Universal Pump

Contents

The Universal Air Sampling Pump ...................................................................................................................... 1

The I.O.M. Sampler ...........................................................................................................................................2

Inhalable Dust Sampling using the I.O.M. Sampler ............................................................................................. 3

Respirable Dust Sampling using the Cyclone Sampler ....................................................................................... 6

Gas & Vapour Sampling using Sorbent Tubes .................................................................................................. 10

Gas & Vapour Sampling using Impingers .........................................................................................................13

Bag Sampling using the Universal Pump .........................................................................................................15

Duct Sampling for Volatile Organic Compounds ...............................................................................................16

The Sample Train ............................................................................................................................................. 17

Sample Train Check List .................................................................................................................................. 17

A helping hand from the experts

This guide is designed as an introduction to the basic principles of air sampling methods. The advice in this guide
deals with the setting up of equipment only.

Advice notes relating to specific sampling methods can be obtained from the HSE (www.hse.gov.uk) and these
will give you a good understanding of the approach you should take to sampling in your particular industry.

As an expert in the field of air sampling, SKC believe in supporting customers every step of the way, so in addition
to the Step By Step guides there is a range of training seminars available to help you get the best from your
sampling equipment.

If you are new to air sampling, our one day seminar 'A Practical Course in Air Monitoring' will give you the help
you need to get started.

The course includes both theoretical and practical sessions in the use of air sampling equipment. An experienced
practitioner will offer valuable input on sampling strategy and will assist with instrument configuration and
calibration. You will soon have everything you need to formulate a professional monitoring programme.

Contact SKC Limited customer services today for details on courses and available dates:

T: [phone]

E: [e-mail]

W: www.skcltd.com

Page 2 224-G3 Issue E www.skcltd.com

The Universal Air Sampling Pump

LCD display Air inlet hosetail

Keypad

Keypad cover

Keypad cover screw

Flow adjust screw

Exhaust port cover

On/off switch

Inlet filter housing

Inlet filter

Inlet filter O ring

Filter housing
screws

Accessory mounting
screws

Flow indicator*

*The flow indicator is for use only to
identify changing flow conditions
during sampling, such as a reduction
in flow caused by a crimped tube. It
must not be used to calibrate the
sample flow rate.

Low flow mode
screw cover

Belt clip

Charging jack socket

Cover over low flow regulator

Battery pack

Battery pack screws

Model depicted - 224-PCTX8

Features vary by model

www.skcltd.com 224-G3 Issue E Page 1

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.

†Foam plug
only required for
respirable sampling

*Not required on
stainless steel
I.O.M. sampler

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.

Spring

Clip

O Ring*

Support

Grid

Cassette

Cap

Front
Plate

O Rings

Foam
Plug†

Cassette

Inlet

Spout

Filter

Cassette

Dust Sampling - Inhalable and Respirable

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

Foam Plug Cassette Inlet Spout

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.

Sampler

Body

Rear view of front

plate showing

O ring positions

Sealing Cap

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.

Page 2 224-G3 Issue E www.skcltd.com

Inhalable Dust Sampling using the I.O.M. Sampler

For information on using the I.O.M. sampler for respirable dust fractions

please contact SKC customer support on [phone]

Inhalable dust is taken to mean any solid particle which
by its small size can be carried in an airflow or remains
airborne. It includes the thoracic and respirable dust
fractions. The inhalable dust fraction size is defined in
the standard EN481. More information is also given in
SKC’s Basic Step By Step Guide (224-G1).

You will need :-

• Universal sample pump (fully charged)

• I.O.M. sampler

• A length of flexible tubing

• Two filter papers from the same box or batch

• Flow calibration device capable of measuring 2

litre/min, such as the Defender primary calibrator
or a rotameter

• ‘Calidaptor’ calibration adaptor for the I.O.M.

sampler

• Toolkit to adjust the pump flow rate

3

0

2

5

2

0

1

5

1

0

0

5

0

3

The correct flow rate for the I.O.M. sampler is 2.0 litre/min

1. Mount one of the filter papers into the I.O.M.
cassette. Place the cassette into the sampler body
and screw on the front cover.

2. Connect the I.O.M. sampler with filter paper fitted,
to the inlet hosetail of the sample pump using the
flexible tubing. The inlet hosetail on the Universal is
mounted on the right hand side of the pump.

3. To set the flow rate required, in this case 2.0
litre/minute, a flow calibration device such as a
Defender primary calibrator or a rotameter, and a
‘calidaptor’ should be used. Make sure the flow
calibrator is capable of measuring the required
flow rate. There are two types of float used in
rotameters. To read them correctly depends on
the type. To read a ball type rotameter correctly
take the reading at the centre of the ball. To read
a float type rotameter correctly take the reading
at the top edge of the float. The float of a float

NOTE: MDHS 14/4
states that a primary
standard such as the
Defender should be used
for flow calibration in
favour of rotameters.

www.skcltd.com 224-G3 Issue E Page 3

Inhalable Dust Sampling using the I.O.M. Sampler

type rotameter is usually marked with a number
of dots. The dots give indication that the float
is spinning in the airflow, thus showing that it
is not touching the walls of the rotameter tube
which could affect the accuracy of the reading.
Note that the rotameter must be placed onto a
flat, level surface to ensure that the float does
not touch the sides of the rotameter tube.

2

5

2

0

1

5

1

0

Ball Type Float Type

Read Here Read Here

2

5

2

0

1

5

1

0

4. The I.O.M. sampler with filter fitted is placed
onto the foam sealing pad on the top of the
calidaptor. Secure the I.O.M. sampler to the
calidaptor using the finger screw, ensuring a
good seal of the front face of the I.O.M. sampler
to the foam pad. The hosetail fitting supplied
with the calidaptor is screwed into the hole in the
bottom of the calidaptor. The calidaptor hosetail
is connected to the hosetail on the Defender
primary calibrator marked ‘Suction’, with the
length of tubing supplied with the calidaptor.
Turn on the Defender primary calibrator
and set it to take continuous flow readings.

with the calidaptor to connect the calidaptor
to the rotameter. Fit the I.O.M. sampler to the
calidaptor and secure with the finger screw.

3

0

2

5

2

0

1

5

1

0

0

5

0

3

6. The pump flow rate is adjusted using the smallest
bladed screwdriver attachment of the toolkit
supplied with the pump. Unscrew and remove
the keypad cover from the pump and switch
on the pump using the on/off switch. Use the
screwdriver tool to turn the adjustment screw
labelled ‘FLOW ADJ’. As the screw is turned
the flow reading on the flow calibrator should
increase or decrease. If this does not happen
check the system for leaks or blockages. One
common cause of lack of flow is by using the
separation papers (usually coloured blue)
sometimes found in boxes of filters, instead of
the filters themselves (usually white). Once the
flow is set to the required level of 2.0 litre/min,
switch the sample pump off.

7. Remove the I.O.M. sampler from the calidaptor
and then remove the filter cassette from the
sampler. Remove the filter paper from the
cassette, and ensure that the cassette inlet
spout and support grid are clean and free of
contamination. Fit the second filter paper into

5. If using a rotameter to set the flow rate, the
calidaptor is designed to screw directly into the
inlet in the top of SKC rotameters. Unscrew the
hosetail fitting supplied with the rotameter, and
screw the calidaptor into the threaded hole in the
top of the rotameter, fastening tightly to ensure
a good seal. If using a non-SKC rotameter, use
the hosetail fitting and length of tubing supplied

Page 4 224-G3 Issue E www.skcltd.com

the cassette. Pre-weigh the filter and cassette,
and then fit the cassette back into the I.O.M.
sampler. Check the flow once again with the pre­weighed filter and cassette in place and make
any final adjustments needed to bring the flow
to the required level. It is advisable to do this
as quickly as possible to minimise the chance
of collecting anything that may affect the final

Inhalable Dust Sampling using the I.O.M. Sampler

result. The I.O.M. sampler complete with the new
filter should now be fitted with the cassette cover
supplied, and is ready to take into the workplace.

New filter
for sample

Filter used for
calibration

8. Mount the sample train (comprising the sample
pump, tubing and I.O.M. sampler) onto the
worker who is to wear it during the sample.
The I.O.M. sampler should be mounted as
close to the breathing zone as is practical and
comfortable. The pump can either be clipped
to a belt or placed into a pouch. Note that the
connecting tube can present a hazard if left
to flap around, in much the same way as a
necktie. Measures should be taken to protect
the wearer by clipping or restraining the tube so
that it cannot become caught up in anything.

30cm

Diameter

Breathing

I.O.M.

Sampler

Zone

cover and switch on the pump. IMPORTANT:
The start time of the sample should be noted.

9. At the end of the sample switch off the pump,
replace the cassette cover and note the finish
time of the sample. Remove the sample train
from the worker, and once away from the
sample location re-check the flow rate of the
sample pump (as per MDHS14/4). Ensure that
the flow rate check is carried out as quickly as
possible to minimise the chance of collecting
anything that may affect the final result. Remove
the filter cassette from the I.O.M. sampler and
post weigh the filter and cassette. If the sample
is to be sent to a laboratory for further analysis,
refit the cassette cover and fit a cassette clip.

The start and finish times, sample duration,
worker’s name, start and finish flow rates pre
and post sample weights and any other relevant

Pump

Once the pump is mounted on the worker
in a satisfactory way, remove the cassette

www.skcltd.com 224-G3 Issue E Page 5

details of the sample should be noted down and
indexed to the filter paper or cassette by number
or code.

Respirable Dust Sampling using the Cyclone Sampler

Respirable dust is taken to be solid particles
which, because of their extremely small size, can
be drawn deep into the lungs, and are not ejected
by the normal means of breathing out, coughing
or travelling out in the lung mucus. It is because of
this ability to stay in the body that it is considered
to be dangerous. Dust of this small size is normally
invisible to the human eye. The respirable dust
fraction size is defined in the standard EN481.
More information is also given in SKC's Basic Step
By Step Guide (224-G1).

You will need :-

• Universal sample pump (fully charged)

• Cyclone sampler and cassette

• A length of flexible tubing

• Filter paper and pre-weighed filter paper from the

same box or batch

• Flow calibration device capable of measuring 2.2

litre/min, such as the Defender primary calibrator
or a rotameter

• Toolkit to adjust the pump flow rate

• Filter transport cassette

3

0

2

5

2

0

1

5

1

0

The correct flow rate for the cyclone sampler is 2.2 litre/min

1. Mount the filter paper that is not pre-weighed into
the cyclone cassette as shown below. The easiest
way to place the filter in the cassette is as follows.

Cassette bottom

Filter

Filter support grid

Cassette top

0

5

0

3

Remove the top half of the cassette and place
it upside down on a flat surface, so that it looks
like a shallow bowl. Place the filter support grid
into the cassette top and place the filter on the
grid. Carefully pick up the cassette top with grid
and filter, and snap the cassette bottom onto the
cassette top. By assembling the filter cassette in
this way the filter remains located centrally on the
support grid.

2. Place the filter cassette into the cyclone sampler
body, mounting it with the embossed text 'SKC
TOP' facing upwards as shown in the figure to
the right. Check that an O ring is fitted into the
circular slot in the bottom face of the sampler
top, fit the sampler top over the cassette and
secure with the retaining ring, tightening firmly
to ensure a good seal. Make sure a grit pot is

Page 6 224-G3 Issue E www.skcltd.com

Respirable Dust Sampling using the Cyclone Sampler

fitted to the bottom of the cyclone sampler.

Retaining

Air

Ring

Outlet

Sampler
Top

3. Connect the top tubing connector (air
outlet) on the cyclone sampler to the inlet
hosetail on the right hand side of the sample
pump using the length of flexible tubing.

Filter
Cassette

Air
Inlet

Sampler
Body

4. To set the flow rate required, in this case 2.2
litre/minute, a flow calibration device such as a
Defender primary calibrator or a rotameter should
be used. Make sure the flow calibrator is capable
of measuring the required flow rate. There are two
types of float used in rotameters. To read them
correctly depends on the type. To read a ball type
rotameter correctly take the reading at the centre
of the ball. To read a float type rotameter correctly
take the reading at the top edge of the float.
Refer to the figure below. The float of a float type
rotameter is usually marked with a number of dots.
The dots give indication that the float is spinning in
the airflow, thus showing that the float is not touching
the walls of the rotameter tube which could affect the
accuracy of the reading. Note that the rotameter must
be placed onto a flat, level surface to ensure that the
float does not touch the sides of the rotameter tube.

2

5

2

0

1

5

Read Here Read Here

2

5

2

0

1

5

1

0

Ball Type Float Type

1

0

Grit Pot

5. Connect the air inlet of the cyclone sampler
to the hosetail on the Defender primary
calibrator marked 'Suction', with a length of

www.skcltd.com 224-G3 Issue E Page 7

Respirable Dust Sampling using the Cyclone Sampler

tubing. Turn on the Defender primary calibrator
and set it to take continuous flow readings.

6. If using a rotameter to set the flow rate, connect
the air inlet of the cyclone sampler to the hosetail
on the top of the rotameter using a length of
tubing. If a 'calidaptor' is fitted to the rotameter,
screw the threaded hosetail fitting supplied
with the calidaptor into the threaded hole in the
bottom of the calidaptor 'bowl', and connect
the cyclone sampler air inlet to the hosetail.

Hosetail

3

0

2

5

2

0

1

Calidaptor
(if fitted to
rotameter)

5

1

0

0

5

0

3

the required level. It is advisable to do this as quickly
as possible to minimise the chance of collecting
anything that may affect the final result. The cyclone
sampler is now ready to take into the workplace.

New filter

for sample

Filter used for

calibration

9. Mount the sample train (comprising the sample
pump, tubing and cyclone sampler) onto the
worker who is to wear it during the sample. The
cyclone sampler should be mounted as close to
the breathing zone as is practical and comfortable.
The pump can be either clipped to a belt or placed
into a pouch. Note that the connecting tube can
present a hazard if left to flap around, in much the
same way as a necktie. Measures should be taken
to protect the wearer by clipping or restraining the
tube so that it cannot become caught up in anything.

7. The pump flow rate is adjusted using the smallest
bladed screwdriver attachment of the toolkit supplied
with the pump. Unscrew and remove the keypad
cover from the pump and switch on the pump using
the on/off switch. Use the screwdriver tool to turn the
adjustment screw labelled 'FLOW ADJ'. As the screw
is turned the flow reading on the flow calibrator should
increase or decrease. If this does not happen check
the system for leaks or blockages. One common
cause of lack of flow is by using the separation papers
(usually coloured blue) sometimes found in boxes of
filters instead of the filters themselves (usually white).
Once the flow is set to the required level of 2.2 litre/
min switch the sample pump off.

8. Remove the filter cassette from the cyclone sampler
body, replace the filter paper in the cyclone cassette
with the pre-weighed filter paper, and refit the cassette
into the cyclone sampler. Check the flow rate once
again with the pre-weighed filter in place and make
any final adjustments needed to bring the flow to

30cm

Diameter

Breathing

Zone

Pump

Cyclone

Sampler

Page 8 224-G3 Issue E www.skcltd.com

Respirable Dust Sampling using the Cyclone Sampler

Once the pump is mounted on the worker in a
satisfactory way it can be switched on. IMPORTANT:
The start time of the sample should be noted.

10. At the end of the sample switch the pump off
and note the finish time of the sample. Remove
the sample train from the worker, and once away
from the sample location re-check the flow rate
of the sample pump (as per MDHS14/4). Ensure
that the flow rate check is carried out as quickly
as possible to minimise the chance of collecting
anything that may affect the final result. Remove
the filter cassette from the cyclone sampler.
Open the filter cassette, carefully lift out the filter
and post weigh it. If the sample is to be sent to
a laboratory for further analysis, carefully transfer
the filter onto the support grid in a transport
cassette and snap the transport cassette shut.

The start and finish times, sample duration,
worker's name, start and finish flow rates, pre and
post sample weights and other relevant details of
the sample should be noted down and indexed to
the filter paper by number or code.

www.skcltd.com 224-G3 Issue E Page 9

Gas & Vapour Sampling using Sorbent Tubes

You will need :-

• Universal sample pump (fully charged)

• Low flow adaptor (tube holder)

• Tube cover of appropriate size for the sorbent tube

being used

• A length of flexible tubing

• Tube adaptor for small diameter sorbent tubes (SKC

part no. 717-511)

• Two sorbent tubes from the same box or batch

• Flow calibration device capable of measuring the

intended flow rate, typically between 5 and 500 ml/
min, such as the Defender primary calibrator

• Toolkit to adjust the flow rate

1. Connect the flow calibrator directly to the sample
pump inlet hosetail using the length of tubing. Turn on
the pump and adjust the flow rate to 1.5 litre/minute.

Note: The sample pump must be in the high flow
mode during this process. This is the required flow
rate for correct operation of the pump's built-in low
flow regulator. Switch off the pump and disconnect
the flow calibrator. No further adjustment of the

pump flow rate should be made.

2. Unscrew the low flow mode screw cover from
the top of the pump as shown, to reveal the
low flow mode screw. Using the large bladed

screwdriver attachment of the toolkit, turn the
low flow mode screw three turns anti-clockwise
to put the pump into the low flow mode.

The combined low flow adaptor and tube holder is
now connected to the pump inlet hosetail using the
length of tubing.

3. Take one of the sorbent tubes and break off both
ends, ideally using a purpose designed tube tip

Page 10 224-G3 Issue E www.skcltd.com

Gas & Vapour Sampling using Sorbent Tubes

breaker. Take care handling the tube as the
broken ends are extremely sharp. Fit the sorbent

tube into the short black hose of the low flow adaptor.

To determine the correct way the sorbent tube
should face, look for a printed arrow on the tube. If
present the arrow should point towards the pump.
The arrow represents the correct direction of the
airflow through the tube. If there is no arrow on the
tube, the largest air gap or unfilled section of the
tube should face away from the pump, that is, to
atmosphere.

4. With the sorbent tube in place in the low flow
adaptor a connection from the free end of the
sorbent tube is made to the hosetail on the Defender
flow calibrator marked 'Suction', as shown.

Tube adaptor for small
diameter sorbent tubes

One of the red plastic caps provided can be used
to seal the sorbent tube until the sample is taken,
however please note that the cap should not be
pressed on too far as they are designed to provide
an airtight seal for transportation. Once pushed fully
home the caps require cutting off with a sharp knife.

Tube Cap

Tube Cover

6. Mount the sample train (comprising the sample
pump, tubing, tube holder and tube cover) onto
the worker who is to wear it during the sample.
The tube holder should be mounted vertically on
the worker, and as close to the breathing zone
as is practical and comfortable. The pump can
be either clipped to a belt or placed into a pouch.
Note that the connecting tube can present a
hazard if left to flap around, in much the same way
as a necktie. Measures should be taken to protect
the wearer by clipping or restraining the tube so
that it cannot become caught up in anything.

Tube must be held
vertical during
calibration

For small diameter sorbent tubes use the tube
adaptor to make the connection to the free end
of the sorbent tube. Switch on the pump and flow
calibrator, and set the calibrator to take continuous
readings. Ensure that the sorbent tube is held
vertically during calibration. Adjust the air flow
rate through the sorbent tube by turning the throttle
valve screw in the side of the low flow adaptor
using the large bladed screwdriver attachment of
the toolkit, as shown above. Once the flow rate is
set to the required level (depending on tube type
and sampling method), switch off the pump.

30cm

Diameter

Breathing

Zone

5. The sorbent tube used to set the flow rate is now
removed from the tube holder and replaced with a
clean tube with both ends broken off. The exposed
end of the tube should be protected with the tube
cover, which screws onto the low flow adaptor.

www.skcltd.com 224-G3 Issue E Page 11

Once the pump is mounted on the worker in a
satisfactory way it can be switched on. IMPORTANT:
The start time of the sample should be noted.

Gas & Vapour Sampling using Sorbent Tubes

7. At the end of the sample switch the pump off
and note the finish time of the sample. Remove
the sample train from the worker, and once away
from the sample location re-check the tube flow
rate. Ensure that the flow rate check is carried out
as quickly as possible to minimise the chance of
collecting anything that may affect the final result.

The importance of blanks:

Sample blanks are in general ignored by a lot of people,
but do offer an important and required benchmark for
accurate samples. Prepare and handle a sorbent tube
the same way as the ones being used for the actual
sample. DO NOT expose the blank tube to any air and

When the sorbent tube is removed from the tube
holder, both ends of the tube should be immediately
capped with the red covers supplied. The start and
finish times, sample duration, worker's name, start
and finish flow rates and any other relevant details
of the sample should be noted down and indexed
to the sorbent tube by number or code.

Tube Caps

cap it immediately with the red covers. When sending
the used tubes for analysis include the non exposed
blank as well. This will allow the laboratory to test the
blank and take into account any variations which are
then applied to the exposed samples.

Page 12 224-G3 Issue E www.skcltd.com

Gas & Vapour Sampling using Impingers

Impingers are typically run at a low flow rate of 1.0
litre/minute. It must first be decided if you are going
to carry out personal or static sampling. If personal
sampling is the method adopted you will require an
impinger pouch and an in-line trap. If static sampling
is more suited an impinger bracket and glass trap
should be used.

Note: Although personal sampling is recommended
by the HSE and the limits in EH 40 are based on
personal exposure, some thought must be given to
the fact that placing glassware filled with, in some
cases, hazardous liquids does present a hazard in
itself. It may, in your opinion, be safer to take samples
on a static basis.

The following section describes how to sample with
impingers on a STATIC basis at a flow rate of 1.0 litre/
minute. If you plan to sample on a personal basis use
an in-line trap and a pouch to attach to a subject.
Details shown in the text on personal sampling are
identified in italics and contained in brackets.

You will need :-

• Universal sample pump (fully charged)

• Impinger

• Impinger trap and trap sorbent

• Flexible tubing

• Bracket (or pouch)

• Flow calibration device capable of measuring the

flow rate intended to be used

• Toolkit to adjust the flow rate

For Low Flow Impinger Sampling

Please refer to the previous section on sorbent tube
sampling. The set up for sampling with an impinger at
flow rates below 500 ml/min is the same as this except
the impinger and trap assembly is substituted in place
of the sorbent tube.

1. Fill the trap with trap sorbent until all of the
holes in the central tube are covered. (Make

sure that the in-line trap is full of sorbent).

3

0

2

5

2

0

1

5

1

0

0

5

0

3

2. Connect from the pipe stub protuding
from the side of the impinger top to the
pipe stub sticking vertically from the trap.

www.skcltd.com 224-G3 Issue E Page 13

Gas & Vapour Sampling using Impingers

(Connect from the impinger to the in-line trap with
a length of flexible tubing. It does not matter which
way around the in-line trap is connected).

3. Fasten the bracket to the front of the Universal pump
using the two screws supplied with the pump. Place
the trap and the impinger into the bracket. (Place

the impinger and in-line trap on a suitable surface).

4. Remove the top of the impinger and fill it to the
desired level with some of the liquid intended to be
used for the sample. Connect with flexible tubing
between the sample pump inlet hosetail and the
pipe stub protuding from the side of the trap.

6. Renew the liquid in the impinger, filling to the
correct level as advised in the method you
are following. The complete unit can now be
placed in the work place and switched on.

(Mount the sample train [comprising the sample
pump, tubing, sorbent trap, impinger and pouch]
onto the worker who is to wear it during the
sample. A length of tube should be run from the
impinger to a position as close to the breathing
zone as is practical and comfortable. The pump
can be either clipped to a belt or placed into a
pouch. Note that the connecting tube can present
a hazard if left to flap around, in much the same
way as a necktie. Measures should be taken
to protect the wearer by clipping or restraining
the tube so that it cannot become caught up in
anything. Once the pump is mounted to the
worker in a satisfactory way it can be switched on).

5. It is important to make sure that the sample pump
is set to 1.0 litre/minute BEFORE switching it on.
If the pump is set to a higher flow rate the liquid
contained in the impinger may well be sucked out
and into the trap or pump. Connect with a length
of tubing between the impinger and a calibration
device. Using the toolkit, adjust the flow adjuster
screw on the pump (labelled ‘FLOW ADJ’). As the
screw is turned the flow reading should increase or
decrease. If this does not happen check the system
for leaks or blockages. Once the flow rate is set
to the required level switch the sample pump off.

3

0

2

5

2

0

1

5

1

0

0

5

0

3

30cm

Diameter

Breathing

Zone

Trap

Pump

Impinger

& Pouch

IMPORTANT: The start time of the sample should
be noted.

7. As the liquid can evaporate quite quickly the impinger
should be checked every 30-45 minutes and topped
up with liquid to ensure the end of the vertical glass
tube inside is always covered with liquid.

8. At the end of the sample switch the pump off, and
note the finish time. Check the flow rate at the end
of the sample. The start and finish times, sample
duration, start and finish flow rates and any other
relevant details of the sample should be noted down
and indexed to the impinger by number or code.

Page 14 224-G3 Issue E www.skcltd.com

Bag Sampling using the Universal Pump

Where there is a need for the sample not to come into
contact with the pump or where the atmosphere may be
aggressive (as found with stack sampling) a method of
collection using an intermediate vessel is recommended.
The intermediate vessel can be any container of adequate
size that is air tight. For example, the SKC Vac-U­Chamber. Some people use large Tupperware containers
if the bags are small, but any air tight vessel, metal, plastic
or otherwise can be used.

You will need :-

• Universal sample pump (fully charged)

• Sample bag of required size

• Vac-U-Chamber or container of adequate size

• Two air tight fittings for lid of container

• Calibration device that is capable of measuring the

desired flow rate

• Toolkit to adjust the flow rate

Please note: The container must be of a large size in
comparison with the sample bag otherwise too much
back pressure is imposed on the pump.

The set up is as shown in the figure below.

A container is prepared by placing two air tight fittings
in the lid, one is for the suction from the pump, the
other is to supply the sample bag with the sampled
air. By turning the pump on, air inside the container

is drawn out producing a negative pressure inside the
container. In order to maintain pressure equilibrium
inside the container, air is now drawn into the sample
bag via the tube to atmosphere.

1. Before placing the bag into the container open
its valve. Pinch closed the tube from the bag to
atmosphere (or sample point) at a point outside the
container.

2. Place the bag into the container and close the lid.

3. When ready to take the sample remove the clamp
from the tube running from the bag to atmosphere.

4. Switch on the pump.

5. When the sample has been taken switch off the
pump and re-clamp the tube running from the bag
to atmosphere.

6. Remove the bag from the container and close the
valve. The tube from the bag can now be removed
without loss of sampled air.

There is no way in which the volume taken into the
bag by this method can be accurately determined,
unless some kind of calibration device is fitted in-line
from the bag to atmosphere. An estimated volume can
be obtained from the flow rate of the pump multiplied
by the run time. This should not, however, be used
to produce accurate results of concentration of
contaminants.

www.skcltd.com 224-G3 Issue E Page 15

Duct Sampling for Volatile Organic Compounds

Unlike dust sampling from a stack, there is currently
NO requirement to carry out this type of monitoring
under 'isokinetic' conditions as detailed in the
standards BS 3405 and BS 893 on stack dust
sampling.

The simplest way to sample for volatile organic
compounds (VOC's) is to use sorbent tubes with a
slight adaptation of the method used in occupational
hygiene. To adapt this method for duct sampling the
simple addition of a probe connected to the inlet end
of the sorbent tube is all that is needed. The flexible

Tube adaptor for small
diameter sorbent tubes

Tube must be held
vertical during
calibration

tubing used to connect the probe to the sorbent tube
must be PTFE as other plastics can affect the sample
due to contamination. The probe should preferably be
PTFE lined or made of glass.

1. Calibration of the sample train is carried out in
a similar manner to that detailed in the section
'Gas & Vapour Sampling Using Sorbent Tubes',
but with the flow calibrator in line between the
duct probe and sorbent tube, as shown below.

The sorbent tube must be held vertical
during calibration.

Duct probe

2. Once the calibration is complete the sorbent tube is
replaced with a new one, the calibrator removed from

Tube must be held vertical
during the sample

Note: The probe must be inserted far enough into
the duct to be in smooth air, away from the walls of
the duct. BS 3405 and BS 893 give details of the
positioning for isokinetic sampling probes for dust
sampling. It is advised that this protocol is referred to
when monitoring for gases.

An alternative to sampling using sorbent tubes is to

the sample train and the sample taken. The sorbent

tube must be held vertical during the sample.

sample using an impinger. If using an impinger, the
liquid media should be replaced after calibration, and
filled to the same level as during the calibration. A
careful eye must be kept on the fluid level during the
sample, as the fluid can evaporate, leaving the impinger
nozzle above the fluid. Refer also to the section ‘Gas &
Vapour Sampling using Impingers’.

Page 16 224-G3 Issue E www.skcltd.com

The Sample Train

The sample ''train'' is the name given to the combination
of a pump, flexible tube and sampling device when
connected together. It does not matter what kind of
sampling device is attached to the pump as there are

Tubing

Sampling

Pump

Device

Sample Train Check List

• Ensure the pump is fully charged and in good condition.

no specific terms for individual setups. The figures
below give examples of sampling trains. Additionally
the figure on the right illustrates the sample train during
the process of calibration.

A 'Calidaptor'
designed for
hands free
calibration

Rotameter

3

0

2

5

2

0

1

5

1

0

0

5

0

3

• Treat the filter media with care.

• Calibrate in a clean area to avoid contamination of the sample media.

• Ensure the flow rate is set at the correct level required for the sampling device or methodology.

• Ensure that all connections are leakproof and secure.

• Mount the sampler in the “breathing zone” - a 30cm hemisphere centred around the mouth.

• Ensure the flexible tube is not left to hang free and become a hazard.

And Finally...

• Always note the sample start and finish time.

• Don’t forget to index the sample media, person sampled, time, date and location, together, preferably on a

form.

• Remember - The result is only as good as the sample taken.

www.skcltd.com 224-G3 Issue E Page 17

Specialists in Air Sampling Technologies

A member of the SKC global group of companies

SKC Limited 11 Sunrise Park, Higher Shaftesbury Road, Blandford Forum, Dorset DT11 8ST United Kingdom

224-G3 Issue E July 2015

T: [phone] F: [phone] E: [e-mail] W: www.skcltd.com