| 摘要 |
PROBLEM TO BE SOLVED: To efficiently remove fine particles sticking to a filter membrane by bringing the filter membrane into contact with gas-dissolved water in which oxygen gas, hydrogen gas, carbonic acid gas, nitrogen gas or a rare gas is dissolved and thereby cleaning the filter membrane. SOLUTION: A nozzle 3 for a bubble jet fluid mixes a gas-dissolved water fed into a water conveying pipe 1 under pressure with gas forced into an air blowing pipe 2 under a high pressure, in the nozzle 3. When the energy of the gas is transferred to the gas-dissolved water, the gas-dissolved water becomes a fine water flow to be ejected to a filter membrane as a high energy water flow from a nozzle outlet 4. In this case, for cleaning the filter membrane, gas-dissolved water in which oxygen gas, hydrogen gas, carbonic acid gas, nitrogen gas or a rare gas is dissolved, is used. Consequently, the number of fine particles residing on a filter membrane is reduced to about 1/10-1/100. Thus it is possible to rapidly and accurately count, for example, the number of fine particles in high-purity water caught by the filter membrane by a low water throughput, when the measurement is performed by identification using a direct microscopic process.
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