Liquid Entry Pressure (LEP) tester is essential when characterizing membranes, especially membranes used in Membrane Distillation processes. The system allows a quick, traceable and reliable automated method to characterize those membranes.
Especially in membrane distillation processes it is of utmost importance that wetting of the membrane does not occur. Therefore, the process must be operated at a transmembrane pressure lower than the LEP of the membrane in order to prevent liquid from permeating through the membrane.
The LEP of the tested membrane is determined by applying small pressure increment steps. After each step the pressure decay is measured. If no wetting of the membrane takes place, the pressure decay will be zero. When wetting starts to occur, a pressure decay is observed and the test is stopped. The user can set the incline at which the pressure steps are applied and can perform a zero calibration to increase accuracy. The design of the Convergence LEP tester allows the user to test both hollow fiber and flat sheet membranes. A 25 mm flat sheet disc holder comes with the system. The unit is controlled with the user-friendly software on an embedded touchscreen and data can be exported via USB.