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Safe & emission free sampling of hazardous liquids, gases & liquefied gases for the UK process industry.

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process industry safety

How many times should I use a Dopak bottle septum?

sampling equipment, consultancy and expertise for your company

This is a common question with a simple answer – a Dopak bottle septum or septa should be used…


This is the only way to guarantee an emission free sample, safer for your plant operator and the local environment. The septa material you select should of course be suitable for your application, there are six materials to choose from and it is the user or plant operator who should make this selection, available options are below;

Dopak bottle septum material options

  • Natural rubber septa
  • Ethylene propylen Diane monomer rubber (EPDM) septa
  • Silicone rubber septa
  • PTFE coated butyl (TCB) septa
  • PTFE coated silicone septa
  • Viton (FKM) septa

Septa are available ex stock from the Dopak factory in many different set sizes all suitable for Dopak sample bottles.

The most basic septa material is natural rubber, this is the lowest cost option. Other materials are available which provide increased chemical compatibility such as PTFE coated butyl rubber or PTFE coated silicone.  It is also important to be aware that the softer septa materials such as natural rubber can accept the larger id needles (6mm!) of Dopak sampling systems whereas the harder materials such as TCB can only accept a process needle id up to 3mm.

If you are unsure which septa material to select then let us know and we will be happy to send you a free sample of the septa for you to test in your laboratory.

Contact Dopak or the UK agent for Dopak to re stock your septa material or give us a call here at Derwent James to discuss the best septa option for your application.

Sampling hazardous chemical liquids with a septum sealed bottle guarantees an emission free sample. Septa are relatively low in cost and the benefit to operator safety are immeasurable. Use septa when sampling.

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