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Cougar Engineering Services
Bird & Tole Air Sampling Products
BTS158 Filter Holder (click for photo/s)
BTS309 Filter Card Holder (click for photo/s)
BTS490 Filter Card Holder (click for photo/s)
BTS495 Maypack (click for photo/s)
Filter Holders

This unit is designed to mount 6cm diameter filters for laboratory or fieldwork. It can be used integrated in a pipeline, or by use of the adapter as an open-ended device.
The main body carries an 1/8” BSPT threaded hole in which is mounted a special screw sealed with an ‘O’ ring. Removal of this screw enables the user to mount the unit on a stand (incorporating suitable sealing), or to mount a pressure gauge to measure the pressure differential over the filter.

The BTS158 can be manufactured in lightweight aluminium alloy or robust stainless steel.

The outlet and inlet of the holder can be fitted with either the standard 10mm OD Tailpiece Adapters or the ‘One-Touch’ pneumatic fittings if specified.

Other fittings / screwthreads are available, please contact us with your requirements. See example photo showing a female thread on a BTS158ILC SS unit (designated SP).


The BTS158F is an open front design with the standard 3/8" BSPT thread on its outlet.

Ordering code:

BTS158F - Open front Filter Holder
BTS158ILA - Filter Holder with Pipe Adapters
BTS158ILC - Filter Holder with 1" BSPP Inlet & Pipe Adapter Outlet

NB: Please specify SS at the end of the order code if Stainless Steel is preferred

The BTS 309 series of filter holder is designed to accept the Bird & Tole Card Mounted Filter so that the filter disk may be handled without touching the sampling area. Records of the sampling may be written on the card if so desired.
Salient points of the BTS 309 Filter Holder
·         The card may be inserted and withdrawn from the filter holder without disconnecting
           the vacuum line.
·         The Filter Holder may be hard plumbed in any sampling line. The unit will seal without a card in
           position so it therefore can be left in the line until required.
·         The standard fitting on the up-stream end is a 1” BSP parallel thread for connection to a
           standard valve. Other end fittings can be produced to order (see photo SP)
·         The Filter Holder can be used as an open fronted unit if required.
·         The BTS 309 Filter Holder can be manufactured in either lightweight aluminium alloy or robust
          stainless steel.

NEW: The BTS309 Filter Holder can now be supplied to house the standard type SAS filter card. Order code is shown below.

Ordering code:

BTS309 - In-Line Filter Holder for B&T cards
BTS309 SAS - In-Line Filter Holder for S.A.S. cards

NB: Please specify SS at the end of the order code if Stainless Steel is preferred

The BTS 490 is designed to be used as a sampling head for environmental air monitoring using a card mounted filter paper (Bird & Tole Card Mounted Filters).

It is suitable for sampling flow rates in the range of 10 – 100 litre per minute (depending on supply).The holder can also be incorporated on the Bird & Tole Air Sampling Unit BTS 601 range.

The unit offers the following features:

  • An aesthetically pleasing design.
  • A hinged cover plate for rapid and positive location of the sampling filter card.
  • Ease of handling involving no physical contact with the sample filter ensuring maximum reproducibility.
  • Adapters available for use with any suitable piped vacuum supply.
 Ordering code:

BTS490 - Panel Mounted Filter Holder
BTS490A - Detachable Filter Holder with screwed cap (for front of BTS601)

The Maypack Insert was designed to carry filters that maximise the absorption or filtration of airborne iodine either in the form of particles or vapour and to fit into the Maypack Adapter BTS495.

The design consists of a cylindrical tube mounted with gauze retainers and locking rings to accommodate the appropriate filter papers and a spring to compress the charcoal bed on assembly to prevent shakedown.

The ‘Maypack’ adapter (BTS 495) is also manufactured by Bird & Tole, to accommodate the insert into a line either using the Stack Sampling unit BTS 327 (The range of sampling flow rates are typically from 10 – 30 litres per minute) or attached directly onto a Bird & Tole Air Sampling Unit’s (BTS 601 Series) Filter Holder.

Assembly of filters in the Maypack (upstream to downstream) is as follows:

  1. A high efficiency particulate filter eg. A Millipore type AA filter or a Whatman glass fibre filter type GF/A.
  2. One or two activated charcoal impregnated filters – typical, Bird & Tole BTS 684.
  3. A bed of 20 – 25g of activated Coconut charcoal (BTS 703) giving a layer about 25mm thick.

As a rough guide:

The airborne iodine collected in the pack may be quantitatively assessed by either direct gamma counting or by separate measurements of the activity on individual components of the pack. The latter can give information on the chemical or physical form of the iodine*.

Millipore glass fibre filter: Iodine absorbed into particals.
Charcoal loaded filters: Iodine vapour and some Methyliodide (Organic iodine).
Charcoal granules: Inorganic iodine compounds as vapour (also iodine vapour & Methyliodide if Charcoal filter papers are omitted.)

Notes on the specification of sampling media

Glass fibre filter - Whatman type GF/A Collection efficiency > 99.9% for particles of 0.6um at a face velocity of 25cm/s.

Carbon paper – Whatman glass fibre, impregnated with Charcoal type ACG/B. Collection efficiency of elemental iodine vapour > 99.9% at a face velocity of 9cm/s.

Charcoal bed of activated charcoal, Sutcliff Speakman 208C 10/18 mesh, derived from coconut shell.

Coconut shell carbons have a very small pore radii and are therefore ideal for adsorption of small molecules, usually in a gaseous phase. Coal based carbons contain larger pores and liquid phase applications to absorb the larger type of molecule.

Ordering code:

BTS495 - Maypack Adapter
BTS492 - Maypack Insert

NB: Please specify SS at the end of the order code if Stainless Steel is preferred

For details on the BTS174 PAS Personal Air Sampler, please refer to 'Air Samplers Tab' found on the top bar of website.
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