| 摘要 |
<p>PURPOSE:To hold the difference of pressures of the inside and outside of a warehouse within a certain limit, to prevent the back flow of air and to maintain cleanliness by installing a plurality o air blowers ventilating the inside of the warehouse mounted on a ceiling, a pressure difference detecting sensor being set up at the specified position of a sidewall and detecting the difference of pressures of the inside and outside of the warehouse and a control section controlling the quantity of the blast of the air blower based on an output from the pressure difference detecting sensor. CONSTITUTION:The periphery of a wafer warehouse is surrounded by sidewalls, a ventilating port 10A is formed to a ceiling and an exhaust port 10B to a floor, and the warehouse has an air blower 21, a control section 50 and a pressure difference detecting sensor 51. On the other hand, clean air A blowing down from the ventilating port 10A from the air blower 21 is made to flow in the warehouse, the greater part of air C are discharged to the outside through a grating 11, and clean air A falls on the surfaces of wafers at all times, thus preventing the adhesion of dust on the wafers. Even when pressure in the warehouse is kept constant, pressure on the inside and outside of the warehouse is fluctuated, the speed of a fan motor 22 is adjusted when pressure difference less out of the range of variation, the quantity of the blast of the air blower 21 is controlled, and pressure difference on the inside and outside of the warehouse is returned within the range of variation, and held at a positive specified value.</p> |
