Air sampling - 4 stage

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Author:
Jag
ID:
100875
Filename:
Air sampling - 4 stage
Updated:
2011-09-10 13:39:42
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P404
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Description:
Air sampling and four stage clearance
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  1. Sampling Equipment

    Filter holders

    To comply with the standard method, an open faced filter holder fitted with an electrically conducting cylindrical cowl extending between
    33 and 44mm
  2. Sampling Equipment

    Filter holders

    a circular area of filter at least ....mm in diameter, should be used for sampling
    20mm. Allows for auniform deposit and protection of the filter.
  3. Sampling Equipment

    The membrane filters must be of mixed esters of cellulose or cellulose nitrate, of pore:
    size 0.8– 1.2 m and 25mm in diameter with a printed grid.

    Printed grids aid both focusing on the plane filters and identifying positions. Any distortions ofgrid lines indicates disturbance associated with poor mounting.
  4. Sampling Equipment

    Pumps

    The pumps must give a smooth flow and be capable of having the flow set to within +?% during the period of sampling (and preferably to within +?%) of the required flow rate and ofmaintaining this flow rate through the filter to within +?% during the period of sampling. Thisvariation includes any change of flow rate with pump orientation.
    10%, 5%, 10%
  5. Sampling equipment

    Pumps

    Static sampling pumps should have the facility to enable the sampling head to be positioned:
    1m to 2m above ground level.
  6. Sampling equipment

    Flow meters

    The airflow must be measured by a flow meter, capable of measuring the appropriate flow rate to within +10 (preferably to within +?%)and which has been calibrated against a primarystandard.
    5%
  7. Cover slip Thickness

    Cover slips must be glass

    Size 1?
    Size 1 1/2
    • 0.13 - 0.16mm
    • 0.16 - 0.19mm
  8. Microscope slides

    Microscope slides must be glass and of a conventional type:
    • 76 mm x 25 mm – length
    • 0.8 mm – 1.0 mm - width
  9. Static Sampling

    Static sampling is normally to be used for the monitoring:
    of airborne fibre concentrationsaround a work area during work periods (i.e. leak testing) or for assessing the suitability of anarea for normal occupation (i.e. clearance testing)
  10. Preparation and Deployment of Sampling Pumps

    Sampling pumps are to be prepared only in
    clean areas
  11. Loading Filters and Preparation of Pumps

    Ensure the sampling heads are clean before use. If necessary:
    wash the filter holders in warmwater or clean them using wet wipes provided in the air testing kit box
  12. Loading Filters and Preparation of Pumps

    Ensure the box of membrane filters intended for use is marked
    on the bottom to the effect thatit has been deemed satisfactory for use
  13. Loading Filters and Preparation of Pumps

    Use ..... ....... tweezers to load the membrane filter into the filter holder with the griddedsurface facing into the projected airflow, checking that the filter packing separation discs havebeen discarded.
    flat tipped
  14. Loading Filters and Preparation of Pumps

    Lower the white ..... ' ring seal onto the filter paper and then carefully screw the cowl intoplace.Close the open end of the cowl with the protective bung or cap to prevent contamination of thefilter during transport to the sampling location.
    PTFE 'O
  15. During clearance testing at stage 3 of the 4-stage clearance process the pumps should beadjusted and set to the appropriate flow rate in the
    outer compartment of the airlock (i.e. thecompartment furthest from the enclosure), or in an area immediately outside (and adjacent to)the enclosure/work area. Calibrated flow meters should not be taken inside the enclosure, toprevent unnecessary contamination of the equipment.
  16. Sampling Duration and Flow Rates

    When the monitoring of airborne fibre concentrations (i.e. background testing, leak testing,reassurance testing, environmental testing and clearance testing) is to be carried out aflow rate of between:
    1 and 14 litres per minute is to be used
  17. Sampling Duration and Flow Rates

    Each sample should be at least 480 litres in volume. When undertaking leak testing it may bedesirable to take a high volume sample for a short time (e.g.
    sampling to acquire volumes of120 litres or 240 litres - grab samples
  18. Sampling Duration and Flow Rates

    If pooling samples to a total 480 litres. Samples that are pooled should be taken within....
    1 minute of each other
  19. Sampling Duration and Flow Rates

    Samples taken over a time of 30 minutes or less may not be accurate to ±
    2% and the resultsare for guidance only
  20. Sampling Duration and Flow Rates

    Reduced sample volumes may also be adopted for routine monitoring outside work areas ifpast experience has shown that the ambient dust levels are likely to lead to filter samples with:
    more than one eighth of each graticule area being obscured by particles and/or agglomeratesof fibres.
  21. Clearance Level Indicator

    The lowest airborne respirable asbestos concentration that the method described in HSG248can reliably detect is ...... fibres / ml for a sample volume of air equivalent to at least 480 litrespassed through a filter with an effective diameter greater than 20mm
    0.01 f/ml
  22. Sampling Locations

    For static sampling the filter holder is to be sited at a height between -----/----- metres
    1 - 2 metres above thefloor in an unobstructed position with the cowl opening facing downwards. Considerationshould, however, be given to relative airflows around the location and the holder should be resited,if necessary, to positions likely to give the highest values of airborne fibreconcentrations. Particular care should be taken in dead spaces where lack of air movementmay prevent a representative sample from being obtaine
  23. Clearance Sampling at Stage 3 of the 4SC Certification Process

    Sampling equipment should be distributed throughout the enclosure with at least.....
    half thesamplers close to or underneath where the asbestos was removed. In tall enclosures (e.g.vertical pipe work or lift shafts), samplers should be placed at representative exposureheights, especially in areas where residual dust may be difficult to detect.

    Wherever possible clearance samples should also be taken adjacent to the inner chamber ofthe airlock and adjacent to the negative air unit filter. If the analyst has reason to believe thatthe airlock is contaminated then sampling shall take place within it.
  24. Clearance Sampling of the Hygiene Unit

    How many air tests shall be carried out and where
    For hygiene units two air tests shall be carried out, one in the shower compartment and the 2ndin the dirty end of the unit.
  25. Leak Air Tests (i.e. Enclosure Check

    Where is this performed?
    This is performed outside the enclosure while asbestos removal work is in progress to checkthat the environmental control systems are adequate.The samples are located where the likelihood of a leak is considered to be the highest.The speed with which results are obtained is more important than their absolute accuracy.Therefore a sample volume of between 120 and 240 litres will normally be collected
  26. Leak Air Tests (i.e. Enclosure Check

    Particular attention should be paid to areas where fibres are likely to escape. These include
    • (1) Around pipes, cables and cable trays, voids etc.
    • (2) Areas where the enclosure is under significant stress.(3) Airlocks and baglocks.
    • (4) Negative air units.
  27. Reassurance Sampling

    During air reasurrance sampling the distribution of sample should cover which sources?
    likely sources of fibreand likely areas of frequent human occupation. Fewer measurements may be generatedduring reassurance sampling than for sampling for certification of reoccupation
  28. Reassurance Sampling

    Air sampling is sometimes required in an area from which an....
    enclosure is/has recently beenremoved (i.e. during or following stage 3 or 4 of the 4-stage clearance certification). This is toensure that there are no airborne fibres emanating from any asbestos residue, which mayhave escaped from the enclosure during the confinement. The sampling protocol should bethe same as for clearance sampling although the sample density may be reduced toadequately cover any suspect areas.
  29. Background Sampling

    background sampling should be carrried prior to what
    • leak sampling, to establish ambient,background fibre levels.
    • During background sampling, the distribution of samples shouldcover likely sources of fibre and likely areas of frequent human occupation. Fewer measurements may be generated during background sampling than for sampling forcertification of reoccupation. Wherever possible background air tests should be taken in thearea where the work is to be carried out to establish an undisturbed fibre level, prior to theworks commencing.


    In order to establish the airborne fibre concentration, background air sampling may also berequired during and/or following minor works on asbestos or following accidental disturbanceof asbestos.

    For these tests a sample volume of 480 litres would normally be taken unless it is felt thats peed of reporting is of greater importance than absolute accuracy.
  30. Environmental Sampling

    Air monitoring is sometimes carried out in premises where asbestos is present but is not being disturbed, in order to determine.....
    Whether there ae measurable fibre concentrations.

    In these cases, static samples are used, usually located between 1 - 2 metres above groundlevel
  31. Decontamination of Sampling Equipment

    All sampling equipment used for asbestos air monitoring must be thoroughly cleaned using what?
    wet wipes prior to leaving the sampling location.
  32. Decontamination of Sampling Equipment

    Sampling equipment used in clearance sampling inside an enclosure must be decontaminated in the:
    third stage of the airlock on exiting from the enclosure

    Sampling equipment used for all other types of sampling outside of an enclosure mustbe decontaminated directly outside the area where sampling has taken place
  33. Number of Air Samples

    The maximum number of air samples which one analyst should supervise at one time is
    12

    If more samples need to be run at any one time or if an analyst considers they cannotsupervise any more work than they are already doing, then an additional analyst should beused. This is due to QC procedures and the number of graticule areas to be counted during asingle day.
  34. Personal Sampling

    All personal sampling for determining exposure to airborne asbestos dust is to be carried outin accordance with the World Health Organisation Method as detailed in HSG248.Personal sampling is used to 1.
    Determine personal exposure to airborne asbestos dust, to ensure that the level ofsuch exposure is controlled to the minimum reasonably practicable below therelevant Control Limit.
  35. Personal SamplingAll personal sampling for determining exposure to airborne asbestos dust is to be carried outin accordance with the World Health Organisation Method as detailed in HSG248.Personal sampling is used to 2.
    Aid in the selection of respiratory protective equipment, dust control equipmentand methods of working.

    Airborne fibre levels will normally be in excess of background levels and the samplingprocedures are to be determined, in each instance, by reference to the World HealthOrganisation Method.
  36. Preparation of Sampling Pumps

    The sampling pumps are to be prepared as for static sampling and should be fitted with a
    waist belt and an adaptor suitable for attaching the filter head assembly to the clothing of the wearer.

    The filter head assembly must always include the electrically conductive cylindrical cowl
  37. Sampling Location

    The sampling pump will normally be attached to the waist belt to minimise inconvenience tothe wearer. The filter holder is to be fixed to the upper lapel or shoulder of the wearer'sclothing as close to the nose and mouth as possible, but in any case within ......
    200mm of them

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