Bubble point or bubble pressure tests are common non-destructive tests for small-area membrane filters, which can ultimately be used to calculate the maximum pore size of the filter material.

What is a bubble point of a membrane filter?

Simple explanation:

The bubble point is the pressure value at which the largest pores of a wetted membrane filter are pressed free.

What should the user do to determine whether the filter is intact?

He must wet the filter with the wetting agent specified in the validation, place the filter outlet under water using a thin hose and slowly place the inlet under increasing gas pressure (generally air is used for this!) From a certain pressure value, air bubbles appear at the outlet of the filter.

This pressure peak at which this happens is called the "Bubblepoint (bubble pressure)" of the filter. Finding this pressure peak is the task of the bubble point filter test

Before a bubble chain can be detected, the applied pressure must overcome the adhesion forces of the filter capillaries. The Mem Flow Test Bubblepoint testers are able to record, display and save this maximum pressure value. With the existing test devices, the Bubblepoint measuring range extends from 5-7000 mbar.

This means that even large-pored filter membranes of 0.2-25µ can be tested safely.

What is the difference between Mem Flow Test Bubblepoint devices and conventional Bubble Point measuring devices?

The most striking difference is that the Mem Flow Test devices always deliver two results:

1. How high is the release pressure of the largest filter capillary (bubblepoint pressure value)?

2. Which bubble point release flow does the bubble point value refer to?

These two pieces of information are required to clearly define bubble point values.