PURPOSE: To measure the perfectness of a membrane filter in a short period of time and with high accuracy, by recording and/or indicating, on an enlarged scale, the detected change of the pressure decrease in a primary chamber of a housing.
CONSTITUTION: An air is introduced in a primary chamber 11a of a housing 11 at time point A. When the pressure within the primary chamber 11a reaches a predetermined constant value at time point B, a start button is turned ON at time point C for recording on an enlarged scale. A recorder 20 accordingly starts recording on an enlarged scale. At this time, an automatic valve 16 is closed to stop the supply of the air. In the case where a membrane filter test piece 12 has perfectness, the gas within the primary chamber 11a is discharged to a secondary chamber 11b, and therefore the pressure in the primary chamber 11a is gradually decreased. However, since the degree of this decrease or reduction in air pressure is considerably minute, it is difficult to read the change or the reduction thereof only by a recording sale used when the pressure is increased. The pressure decrease is not confirmed before the pressure is remarkably reduced. Accordingly, if the output of a pressure sensor 19 is recorded and indicated by the magnification thereof, for example, as large as ten times (P1→P2) and (P2→P3), the pressure decrease can be easily read out.
MISAWA OSAMU
FURUMOTO HIROYUKI
TOKYO AIRCRAFT INSTR CO