Abstract: A method of predicting logarithmic reduction values for a membrane filtration system having a filtrate flow portion and a bypass flow portion relative to a filtrate permeable membrane with stable input gas flow comprising: determining the filtrate flow rate through the membrane under the action of an applied test pressure, determining the membrane bypass flow rate using integrity test measurements and estimating the logarithmic reduction value using the ratio of determined filtrate flow rate and determined bypass flow rate. Methods of testing the integrity of a porous membrane are also disclosed.

Abstract: A method of determining one gas in the presence of another, where the one gas is reactive with an electrochemical product of the other, comprisesapplying the gases to one side of a membrane permeable to the two gases, the other side of the membrane retaining a solvent for both gases and for the electrochemical product,applying, for the predetermined duration through a working electrode in contact with the solvent, a potential which electrolyses (e.g. reduces) the (dissolved) other gas to form the said electrochemical product,applying, through the working electrode, a potential for reconverting the product to the dissolved gas,measuring, at a predetermined instant or integrated over a predetermined time slot, the current flowing at the reconversion potential, and,from the amount by which the measured current (or integrated current, i.e. charge) falls short of the current when the said one gas is absent, determining the concentration of the said one gas.