Abstract: An apparatus for detecting defects in porous elements including systems and methods for quantifying acoustic signal data. A transducer receives acoustic signals generated within a test chamber by a porous element. A signal processing device may be included for analyzing the acoustic signals received, for quantifying the acoustic signals, and for correlating the acoustic signals with physical attributes of the porous element.

Abstract: A method for manufacturing tubular shaped thermoplastic members comprising conveying two thin sheets of thermoplastic material in close substantially parallel relationship through an ultrasonic welding station for forming a plurality of continuous spaced apart seams substantially parallel to the direction of conveying for joining the two sheets of thermoplastic material. The seams, thus formed, are cut substantially parallel to the direction of conveying such that the two sheets of thermoplastic material remain joined adjacent each side of the cuts. Preferably, the cutting takes place substantially simultaneously with the ultrasonic formation of the seams and the thin sheets of thermoplastic material are cooled prior to the ultrasonic welding. An apparatus for practicing the method is also disclosed. The method and apparatus are particularly adaptable for the manufacture of ionically permeable thermoplastic separators for use in electrochemical cells and the like.