Liq. leakage in double-walled storage vessels signalling device - maintains low pressure in protection space, and pressure rise is taken as leak criterion (SW 18.9.78)

摘要

On the storage vessel wall is partly or completely surrounded with a liquid. Pressure in test space monitored for liquid penetration is kept below atmospheric pressure by a vacuum pump operated with a pressure and/or time dependent control. Separate evacuation and pressure measuring pipes are provided. When the pressure in the test space rises owing to unavoidable small harmless leakages, it is automatically maintained within a certain rated pressure range. Delay or failure to reach the pressure range lower threshold is taken as the criterion for a leak. Means are provided which signal a pressure rise in the evacuation pipe above the lower pressure threshold as the leakage criterion.