Diffusion caps
Diffusion caps are used to define the air gap between the sampling environment and sorbent surface during diffusive sampling (also known as axial or passive sampling). Used in combination with a single-bed sorbent tube, penclip and aluminium long-term storage cap (at the other end of the tube), diffusion caps offer a simple to use, lightweight approach to personal monitoring.
- Defines the air gap for diffusive sampling at 15 mm, allowing use of published uptake rates
- Prevents small insects/particulates from entering the tube
- Complies with standard methods such as US EPA Method 325
Custom etched caps are not available for online purchase - please contact sampletech@markes.com
Product List
Showing 5/5 results
Diffusion cap- aluminium, for passive sampling- 10 pack
Product Code
C-DF010
Diffusion cap- aluminium, for passive sampling- pack of 100
Product Code
C-DF100
Diffusion cap- stainless steel, for passive sampling- custom material: stainless steel- pack of 20
Product Code
C-DFS20
Diffusion cap- aluminium, for passive sampling- CUSTOM ETCHED - 10 pack
Not available for online purchase
Product Code
C-DF010E
Diffusion cap- aluminium, for passive sampling- CUSTOM ETCHED - pack of 100
Not available for online purchase
Product Code
C-DF100E
Overview
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.
Part numbers:
C-DF010 - C-DF010E - C-DF100 - C-DF100E - C-DFS20
