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AS100/AS200
Personal Air Sampler
Instruction Manual
Munro Instruments Ltd, Gilbert House, 406 Roding Lane South,
Woodford Green, Essex, IG8 8EY, UK
Phone: +44 (0) 20 8551 7000 Fax: +44 (0) 20 8551 4565
Email: [email protected]
AS100/AS200 Personal Air Sampler
INSTRUCTION MANUAL
Contents
Chapter
Description
Page
Introduction
1
1.1 Schedule of parts
1.2 Applications
1
1
2
Specification
2
3
Order Codes
3
4
Operating Instructions
4
4.1 Batteries and battery charging
4.2 Fitting a filter paper
4.3 Flow rate setting
4.4 Sampling
4.5 Handling of filter papers
4.6 Timer (AS200 only)
5
6
8
8
9
11
Servicing
11
1
5
Munro Instruments
Gilbert House, 406 Roding Lane South
Woodford Green, Essex IG8 8EY
Telephone 020 8551 7000 Fax 020 8551 4565
Issue 4 July 2014
AS100/200 Personal Air Sampler
1.
Introduction
1.1
Schedule of parts
The AS100 and AS200 Personal Air Samplers are supplied either as single
instruments or as part of standard kits for general dust monitoring. The following
items are supplied in the kit (filters and holders may differ).
1.2
Qty
1
AS100 or AS200 Personal Air Sampler
Qty
1
Battery Charger
Qty
1
Harness
Qty
1
Pair of Tweezers
Qty
1
Screwdriver
Qty
1
Carrying Case with insert
Qty
1
Instruction Book
Qty
1
25mm open face filter holder with lapel clip and 1m of tubing
Qty
1
Pack of 100 Whatman GF/A 25mm filter papers.
Applications
The AS100 Personal Air Sampler is designed for use by Occupational Hygienists,
Factory Managers and others concerned with sampling in environments likely to
contain airborne dusts or fumes from which personnel must be protected. It will be
particularly useful for assessments in connection with the COSHH Regulations.
A personal sampler is the only way to measure the true exposure to airborne dusts
or fumes of personnel who are very mobile, or who work in areas in which the
degree of air pollution varies widely during the working period.
The results from analysis following sampling can be used to confirm that the
wearer is not being exposed to dust concentrations in excess of the Occupational
Exposure Limit laid down in HSE Guidance Note EH40
* The Guidance Note lists concentration limits for a wide variety of potentially
hazardous dusts, gases, vapours etc.
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The Sampler is built round a diaphragm pump driven by a small d.c. motor.
Diaphragm pumps have few moving parts and mechanical power losses are very low.
As a result, their power conversion efficiency is relatively high. The cost of this
efficiency is marginally higher noise in operation and pulsation in the air flow.
Noise is reduced by interposing insulation between the pump and the sampler case
and pulsation is controlled by use of a smoothing box.
Higher power conversion efficiency allows a smaller battery to be used, reducing both
the sampler weight and its cost.
Flow stabilisation is achieved by use of a closed loop electronic feed-back system;
this results in a virtually flat response over a wide range of working conditions.
When the battery is discharged, the motor is cut off automatically and the LED colour
changes from Green to Red to warn the user.
The AS200 incorporates a timer, allowing sampling times to measure with great
accuracy. .
2.
Specification
Sampler unit
Flow Rate
0.5 to 2.5 l/min stabilised to within ±5%.
Maximum load
2 l/min - 12" WG
Filter size
25mm standard; 37mm optional.
Carrying attachment Belt clip; kit incl. harness.
Rechargeable battery Ni-cad 3.6V 1.2Ahr. Recharge time 14 hr. @ 100mA.
Average current 80 to 100mA.
LED indicator
Yellow/Green - pump running
Red - Battery discharged.
Accessories
Sampling heads
Battery charger
Harness
Calibrator
Filters
25mm & 37mm open face filter holders.
25mm cowled filter holder.
Cyclone for respirable dust separation; (but see text).
240V ac input; 100mA output.
6-way 100mA and Auto chargers are also available.
Strong webbing belt with shoulder strap.
To set up the flow rate.
Selection available
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3.
Order codes
AS100
Personal Air Sampler
AS200
Personal Air Sampler with integral timer.
RM 1108 100mA Battery Charger
NR720
6 way 100mA Battery Charger
RM1115 Open face filter holder, with lapel clip & 1m hose.
RM1272 Lead-in-air filter holder, lapel clip and 1m hose
RM 1127 Spare sample can
RM 1112 Harness with shoulder strap and belt
RM 1110 Cyclone (separates respirable dust).
RM 1156 Pack of 5 x 25mm Cassettes for Cyclone
RM 1111 Pack of 5 x 37mm cassettes for Cyclone
FL 1701 Pack of 100 25mm 0.8µm Membrane filters
FL 1702 Pack of 100 37mm 0.8µm Membrane filters
FL 1726 Pack of 100 25mm 0.8µm Gridded Membrane filters
FL 1705 Pack of 100 37mm 0.8µm Gridded Membrane filters
FL 1720 Pack of 100 25mm GF/A filters
FL 1721 Pack of 100 37mm GF/A filters
Note about sampling heads. The standard open face filter head is used for general
air sampling. The cyclone is designed to separate out dust defined as 'respirable' by
the Johannesburg Conference. The flow rate must be 2.2 litres per minute for this
separation to be achieved.
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4.
Operating Instructions
IMPORTANT NOTE Do not run the pump without a filter holder and filter fitted
4.1
Batteries and battery charging
A fully charged battery in good condition will run the sampler at a flow rate of 2 l/min
for between 8 and 12 hours, depending on the type of filter in use. The maximum
sampling time will depend on how well the battery is maintained, and will in any case
decrease over time as the battery ages.
A fully discharged battery requires 14 hours to recharge using the 100mA charger.
No harm is done by leaving the battery on charge for a slightly longer period. Do not
leave a battery on charge over a full weekend.
If a battery is not used for some time, full capacity may not be restored until several
charge/discharge cycles have occurred.
If a Sampler is regularly used for short samples followed by recharge, and is suddenly
required to provide a long sample, the battery may not be able to cope. This is due to
a memory effect, common to NiCad batteries. Unless curative action is taken, the
battery only becomes able to provide the output for which it has been regularly used.
The cure is to run the battery until it is fully discharged and then recharge it.
To prevent the memory effect developing, the Sampler should be run occasionally
(say, monthly) until the battery is completely discharged, and then given a full charge.
The need to recharge a battery is indicated by the LED on top of the instrument
changing from Yellow/Green to Red. The pump will not run when the LED is in the
Red state.
Charging the battery
1.
Check that the AS100/200 is switched OFF.
2.
Connect the miniature jack plug on the battery charger lead into the socket on
top of' the AS100/200.
3.
Plug the charger into a mains socket and switch on.
4.
Leave the battery on charge for about 14 hours, (overnight), but not over a
weekend.
5.
If a battery is only partly discharged, and then recharged, the memory effect
described earlier may develop. This will cause no harm, but will prevent the
battery giving its full capacity until remedial action (full discharge and
recharge) has been taken.
An auto-charger will recharge a 'flat' battery in approximately five to six hours. A
partially discharged battery will be recharged even faster. In either case, the charging
rate will fall to a low (trickle) value when full charge is detected. The battery can
then trickle charge indefinitely without harm, and remain ready for instant use.
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4.2
Fitting a filter paper
All filter paper handling should be carried out in 'clean room' conditions. Filter
papers to be weighed should be allowed to stabilise in the environment of the
laboratory or room in which the balance is located, preferably overnight.
4.2.1 Using an open face filter holder
If the subsequent dust analysis is to be by weight (gravimetric analysis) filter papers
must be pre-weighed and kept in identifiable sealed containers until they are to be
used.
If a filter head with paper fitted is used to set up and check the sampler, the paper
should be discarded and a new one, pre-weighed if necessary, fitted just before
sampling is to start. If possible, a spare holder should be kept for setting up.
1
2.
Unscrew the filter cap, taking care not to lose the sealing '0' ring
Place a clean filter on the support grid using tweezers; this avoids contamination
and damage to the paper. If using membrane filters for the first time, ensure
that a filter is selected and not a blue separator paper
If the paper is pre-weighed, keep it in its labelled container until it is required for
use, and ensure that it goes back into the same container after use.
3.
Place the '0' ring over the filter paper, followed by the orifice plate, if sampling
for lead in air, or the 7-hole insert if sampling for total dust.
4.
Return the end cap and screw it up firmly. Do not over tighten, as this may
damage the filter.
4.2.2 Using a cowled filter head for asbestos
NOTE Details of methods of sampling for Asbestos dust are given in HSE
publication EH 10.
1.
Proceed as in section 3.2.1 and note that the cowl replaces the normal end cap.
As asbestos is measured by counting fibres under the microscope, pre-weighing of
tile filter is not necessary.
2.
After assembling the holder, place the red plastic cap over the end of the cowl
until sampling is about to start, this will prevent contamination of the filter.
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4.2.3 Using a cyclone
1.
The filter paper is weighed and pre-loaded into a cassette which is placed into
the cyclone just before sampling commences. Cassette loading should preferably be
done by the laboratory weighing the filter. The cassette is then numbered for
identification and returned to the laboratory for unloading after use.
2.
To pre-load a weighed filter paper, remove the clip holding the cassette
together, and separate the parts on a clean surface, pointing downwards.
3.
Place the cone section on a clean surface, pointing downwards. Place the
support grid on top of the inverted cone.
4.
Using tweezers, remove the filter from its numbered container and place it on
the grid. Finally, place the other half of the cassette on top.
5.
Clamp the assembly together using the "miniature headphones clip. This
holds the assembly together and also prevents contamination of the paper.
6.
To prepare for sampling, undo the knurled ring on the cyclone and lift off the
outlet tubing adapter.
7.
Remove the clip from the prepared cassette and place the cassette into the
cyclone body, cone side upwards.
8.
Place the outlet tube adapter over the cassette and lock it in position with the
knurled ring.
9.
Check that there is a rubber grit-pot on the bottom of the cyclone. This pot will
collect the larger non-respirable dust rejected by the cyclone and must be
emptied after each sample has been taken.
In certain cases this pot may be weighed before and after sampling to assess the
quantity of larger dust. In this case a bung is used to seal the pot after sampling is
completed.
4.2.4 Quartz dust measurement
Quartz dust is measured using a cyclone and special filter papers. As with any
sampling, the laboratory performing the post-sampling analysis should be consulted
about the best filtering medium. In the case of quartz dust, analysis may be carried
out by gravimetric measurement, infra-red absorption or chemical analysis following
ashing.
The filter medium used must have negligible silica content (which rules out glass fibre
filters) and must also be transparent to infra-red light if this technique is to be used. A
typical recommended filter medium is the Gelman DM Metricel PVC filter; other
makes may be suitable. The same handling procedures as above must be observed.
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4.3
Flow rate setting
An external calibration flowmeter is required to set the air flow. It can be coupled
directly to an open face filter head or a cowled filter head by pressing either firmly on
to the black sponge rubber washer.
To couple a Flow Gauge to the Cyclone, insert the screw-in stub into the top of the
flow gauge and connect it to the inlet stub of the cyclone, using a short length of
plastic tubing,
If the stub is not available, a spare open-face filter can be used. (See diagrams)
i.
Run the AS100/200 for about 10 minutes with a spare filter head and filter
paper fitted to warm up the pump. (Do not use this filter paper for actual sampling).
ii.
Connect the loaded filter head (open, cowled or cyclone) to the sampler using
the plastic hose. Switch the sampler ON. With the filter head pressed down on to the
calibrator, use the slotted screw on the front of the sampler adjust the flow to the
required value. If the gauge has a ball float read the gauge mark at the middle of the
ball, if the float is bullet-shaped then read the flow indicated by the top of the float.
iii.
Switch off the sampler, and replace the cover on the cowled holder unless
sampling is to start immediately. Protect all heads from contamination by storing
them in plastic bags until they are required for use.
4.4
Sampling
i. If the harness is to be used, it should be fitted and adjusted until it is comfortable.
Both the shoulder strap and the waist belt are adjustable and there are four alternative
fastening positions for the shoulder strap at the rear of the belt.
ii. When the harness is comfortable, the AS100/200 should be attached to the belt to
suit the user. Just behind the right hip is a common position.
iii. The cyclone or filter holder should be attached to one of the slots on the shoulder
strap to be as close to the mouth as convenient. The hose should be led back over
the left shoulder to connect to the sampler.
iv. If a harness is not used, clip the sampler to a waist-belt in the most comfortable
position for the user. Similarly, the filter head or cyclone should be clipped to a
lapel or pocket to be as close to the user's mouth as possible, i.e. within the user's
breathing zone,
v· Switch on the sampler and check that the Sampler LED is lit and showing Green.
Sampling is now in progress.
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NOTE on flow rate
The flow rate and maximum sampling time that can be achieved by a portable sampler
are both related to the type of filter paper to be used.
The resistance or restriction to air flow offered by a filter paper of given diameter
depends on the material from which it is made. Generally, glass fibre filter papers
have low restriction, while membrane filters have a high restriction.
Because more energy is used drawing air through a high restriction filter paper, the
maximum sampling period available from a battery between charges is shorter. The
period will also be shorter if a higher flow rate is selected. Although it is difficult to
be precise, the table below gives an idea of the sampling periods to be expected from
a properly charged battery in good condition.
Flow Rate (l/min)
Type of filter
Membrane (0.8µm)
Membrane (1.2µm)*
Glass fibre GF/A (1.6µm)
1.5
10+ hours
14 hours
12+ hours
2.0
8 hours
8 hours
10 hours
*Can be used for asbestos with the approval of the analysing laboratory.
If the performance times shown above are not achieved, check first that proper battery
charging procedures are being used, and consider whether the battery memory effect
is causing a problem.
4.5
Handling of filters after sampling
Once sampling is complete, the filter should be unloaded as soon as possible
and handled carefully at all times.
Open face filter
i.
After switching off the sampler and removing the filter head from the user, it
should be carefully transferred to the unloading point.
ii.
Have a sample can ready; if the filter was pre-weighed, this should be the
same can from which it was taken.
iii.
Carefully undo the cap and, using tweezers, remove the '0' ring and then the
filter. Place the filter in the sample can and label the can with date, location
etc.
Transfer to the laboratory as soon as possible. The filter must be in the laboratory
environment for a period (usually overnight) to stabilise before it is re-weighed.
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Calculation of dust concentration
The dust concentration measured during sampling is found as follows Concentration (mg/m³) = W x 1000
F x ST
Where
W = Weight of dust collected (mg)
F = Flow rate of sampler (litre/minute)
ST = Total Sampling Time (minutes)
The resulting value can be compared directly with Exposure Limits laid down by the
HSE or other authorities.
Asbestos filter
i.
After switching off the sampler, place the red protective cap over the cowl
immediately. Transfer the filter head carefully to the unloading point.
ii. Have a labelled sample can ready. Carefully undo the cowl and remove the '0'
ring using tweezers. Then remove the filter paper and place it in the can. The
filter can be attached to the can by adhesive tape, taking care not to touch the
exposed area.
iii. Label the can and send to the analysing laboratory as soon as possible.
Cyclone
i.
After switching off the sampler, remove the cyclone and undo the locking ring.
Remove the cassette and place the clip in position to prevent the cassette falling
apart. The whole cassette should preferably be sent to the analysing laboratory
rather than being unloaded on site.
ii. At the unloading point, remove the clip with the coned end of the cassette
downwards. Remove the round end carefully.
iii. Lift the filter with tweezers and place in a labelled sample can for transportation
to the analysing laboratory. If possible, transport with the loaded side upward.
If it is a preweighed filter, ensure that it is returned to its original can or the presampling weight will not be known.
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NOTES
1.
To ensure traceability, a simple system of identifying sample cans must be
devised. If filters are to be pre-weighed, the laboratory should be asked to
prepare say, a week's supply and a few spares, each can having a unique
number. After sampling, the label should have date and location details added,
or these details should be separately logged for future reference.
2.
The sampling head should be thoroughly cleaned after use.
4.6
Timer
1.
The AS100 has no timer fitted.
2.
The AS200 is fitted with a timer counting in hours, minutes and seconds. The
timer is fitted with its own battery having an 8-year life expectancy. Operation is
as follows.
i.
Before the sampler is first started, the Red button on the timer should be
pressed to set the display to zero (unless it is already showing 0.00).
ii. Timing starts as soon as the sampler is switched on. If sampling is stopped
by switching power off, the time display freezes at the final time. If the
sampler is restarted, timing will continue from the previously frozen value,
unless this has been reset. This feature ensures that true exposure time is
recorded even if the operator switches the sampler off during a dinner or
other bread.
iii. If the pump switches off because the battery is discharged, the clock
display will again be frozen and display the actual sampling time.
5.
Servicing
5.1
General
Apart from keeping the batteries in the AS100/200 charged, no day-to-day
maintenance is required. However, filter holders and cyclones must be cleaned every
time that they are used
Do not run the pump, even to check it, without a filter fitted. Such running will
introduce dust into the pump and cause premature wear and clogging.
The inlet tube of the pump contains an in-line sintered bronze filter to block coarse
dust particles. However, this is only a partial protection A filter to trap all dust would
reduce the efficiency of the pump.
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5.2
Loss of performance
In general, if performance is failing off, there are several likely causes.
i.
A valve or the diaphragm is damaged.
ii. Dust particles have entered the pump and lodged under a valve, preventing it
operating properly.
iii. The battery has lost capacity.
iv. Although less likely, the battery charger may be faulty.
5.3
Battery checks
The battery is a sealed unit, which limits the testing possibilities. If the battery has
been run until the Red LED lights, place it on charge for a full 14 hours, (or if using
an Autocharger, until the Orange LED goes off and the Green comes on). If it does
not then run for the normally expected period, the discharge/charge cycle should be
repeated. If there is no improvement in performance, the battery should be replaced.
5.4
Battery charger
It is unlikely that the battery charger is running a low charge current it will either run
at 100mA or not operate at all. However, if a multi-meter is available the charger can
be checked as follows.
The open circuit output voltage at the jack plug should be approximately 19V d.c.
with the tip positive. The short circuit current between tip and ring should be 100mA
d.c. (Use the 1A d.c. range). The charger will not be damaged by this check.
5.5
Service at Munro
If it is necessary to return an instrument for service you must contact Munro
Instruments Limited and complete a “Notification of Repair Return” form before
sending the unit back. Please address your instrument to the Service Department at the
address shown at the front of this Manual. If possible, please include a note of the
symptoms that preceded failure.
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