Buy online at

What is DOP (Dispersed Oil Particulate) testing?

DOP testing is the process in which the integrity of your HEPA (High Efficiency Particulate Air) or ULPA (Ultra Low Penetration Air) filter is tested through the introduction of particulates.

Oil is dispersed as an aerosol into the upstream flow of the filter media while the number of particles in the downstream flow is measured using a calibrated photometer.

With cleanrooms often protecting mission critical environments, filter integrity and efficiency is vital; HEPA filters are tested to 99.99% @ 0.3 micron efficiency with ULPA filters tested to 99.9995% @ 0.12 micron. During the DOP the whole filter face is tested to ensure that any damage or leak will be detected and located.

If a filter is found to fall outside of the specified efficiency standards, our engineers are trained and competent to replace the filter media quickly on site to resolve the fault, this ensures that your cleanroom down time is kept to an absolute minimum and allows your business operations to resume quickly.

Why have a DOP test?

Equipment using a HEPA or ULPA filter should be tested every time the equipment is moved to ensure no damage due to transportation has occurred and at regular intervals.

If your filter is not working efficiently you run the risk of contamination entering your cleanroom, potentially impacting on your processes and product quality and, in turn, affecting your cleanrooms classification. A DOP test can therefore reduce costly product recalls, saving money, time and preventing damage to your brand.

Book your DOP filter integrity test

Connect 2 Cleanrooms have three engineers CTCB certified to professional standard, to achieve this status our engineers have had to demonstrate over 5 years' experience before the exam can even be sat. 

If you would like to book a DOP, validation or would like more information please email

Contact us»