JPS57105218A - Tank - Google Patents

Abstract

PURPOSE: To obtain a tank fitted with a filter which has a high efficiency in trapping fine particles of specified particle diameters and shows a low pressure loss by a method wherein a filter in gas discharge and intake valves for a tank used for storage or in a production process is composed of fluororesin fibers whose fiber diameter, fiber-to-fiber distance, porosity and thickness are specified.

CONSTITUTION: The tank has the filter fitted in the gas discharge and intake valves, which filter consisting of a woven and stacked structure of fluororesin fibers having a fiber diameter of 0.01W10μ, a fiber-to-fiber distance of 0.04W40μ, a porosity of 30W 95% and a thickness of 0.02W2mm. The fiber diameter and the fiber-to-fiber distance specified above are required for achieving a trapping efficiency of 80W100% in filtering the particles of a diameter of about 0.3μ, such as bacteria, which have been said to be trappable only at a low efficiency. And, the porosity and the thickness specified above are needed to be effective for decreasing the pressure loss to a desired value. When the fiber diameter and the fiber-to-fiber distance are larger than the respective upper limits, the trapping efficiency is reduced to below 80%, and on the other hand, when the diameter and the distance are smaller than the respective lower limits, the resulted strength is insufficient which leads to an excessive pressure loss. A porosity less than the lower limit leads to a large pressure loss, while a porosity larger than the upper limit results in an insufficient strength.

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