A diffusion cap replaces the long-term storage cap at the sampling (grooved) end of the sorbent tube for the duration of the sampling period. It is made of anodised aluminium and contains a stainless steel gauze.

When used for personal monitoring/occupational hygiene, the tube should be mounted in the breathing zone of the worker; for example on the lapel of their jacket, with the cap facing up. Markes recommends using diffusion caps in combination with aluminium long-term storage caps and stainless steel penclips to ensure that the sorbent tube is as light as possible, minimising unconscious changes in behaviour by those being monitored.

When used for fixed-location sampling, a suitable sampling site should be chosen. Markes recommends the Field Station for passive sampling (EPA 325), which houses up to five sorbent tubes in a vertical position.

Note: The diffusion cap should be facing down for this sampling approach.

Typical sampling durations for diffusive monitoring are 8 hours for workplace monitoring and 1–4 weeks for ambient and indoor air monitoring.

For traceability purposes, diffusion caps can be supplied etched with a unique four-digit serial number. Contact us for options.

For further support, please contact:

COE team Email: info@transmed.com.vn Hotline: 0949 934 595