21 - 05 - 2019, by Convergence Industry

Striving for Awesomeness – Redesigning BP measurements

State of the art

A bubble point test is a pretty straightforward test used in quality control and characterization of membranes: An increasing gas pressure is applied on a membrane sample submerged and filled with a wetting liquid. The pressure at which the first continuous bubble stream emerges is called the bubble point and is linked to the pore size of the membrane. In praxis, this test is often performed manually: the pre-pressure is set using a reducing valve and the bubble point determined by looking for the first continuous stream of bubbles. This process is tedious, time-consuming and results are in the worst case dependent on the operator. This is where Convergence Industry steps in: we decided to develop a reliable and automated method for bubble point detection.

Idea generation

When designing the process three things stood out as being the most important to us: compliance to standards, user-friendliness and versatility of the product. We decided to both comply to ASTM F316-03 as well as the ISO4003 and engineered the system accordingly. To increase user-friendliness, the decision to include an easy-to-use touchscreen interface into the front of the unit was made. And to make our bubble point tester more versatile we created two versions: one that can be operated with compressed air and one that has a built-in air compressor. The system will measure the bubble point by applying a constant pressure slope to the membrane and measuring the necessary air flow. As soon as bubbling occurs the air flow should increase and the first bubble point can be determined.


Of course an idea is only as good as its execution. That’s why we went to our in-house research and development facility, set up a test stand and tested our concept on commercially available membranes. And voilà, testing showed that the membranes bubble point could reliably be determined. With continued testing we began to get a feeling on the systems limitations, which enabled us to cut down the required time for one test to under 2 minutes.

Design work

Now that the concepts was proven to work we could focus on the final touches: creating an easy-to-use software interface and designing an aesthetically pleasing but functional system design. In the picture on the right you can catch a first glimpse at the would-be design: the integrated touchscreen puts all the functionalities of the software at your fingertips and the filter holder makes it easy to quickly attach different filters.

So in the end only one question remains: how can we help you improve your process?

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