APPARATUS AND METHOD FOR MEASURING THE FILTERABILITY OF A FLUID

A cold box (12) has a temperature regulating mechanism (14) connected thereto. In the cold box a filter holder (24) is connected between first and second cylinders (26 and 28). The filter holder has a housing in two parts held together by a quick attachment and release mechanism (34) which permits a calibrated filter to be inserted and removed easily. The first cylinder (26) contains a free piston (50) which separates a quantity of fast fluid from a pressurized inert gas (56) which is supplied to an opposite side of the piston. The pressurized gas forces the fast fluid through the calibrated filter to the second cylinder (28) where it impinges on another free piston (66). This free piston is biased by gas pressure (pressure regulator 84) so that back pressure is created across the filter to simulate actual conditions which would occur in a full-size device, such as an engine. The rate of flow at a given temperature is measured by a flow meter (78) or by measuring the time for a predetermined volume of test fluid to be displaced (calibrated indicator rod 68 fixed to piston 66).