| 摘要 |
PURPOSE:To control the flow rate of raw gas in a highly precise manner by a method wherein the time opened of a high speed valve, in which a piezoelectric element and the like is used, a repetitive frequency, the pressure in front and in rear of the valve and the like are properly controlled. CONSTITUTION:A high-speed valve 4 is provided on the second gas supply pie 2 into which carrier gas is sent, and it performs the function of introduction and shutting out of the source gas sent from the first gas supply pipe 1. While a growing operation is performed, the flow rate is controlled by a mass flow controller 3 in order to make uniform the pressure of source gas constant. When a high speed value 4 is opened, the source gas flows into the second gas supply pipe 2 from the first gas feeding pipe 1, it is mixed with carrier gas and sent to a reaction furnace. When the indicated value of a pressure gauges 6 and 7 is set at P6 and P7, the quantity of flow of source gas runs into the feeding pipe 2, it is mixed with carrier gas and sent to a reaction furnace. When the valve of the pressure gauges 6 and 7 indicate P6 and p7, the flow rate of source gas is in proportion to the product of the opened time of the high speed valve 4 and its respective frequency of P7X(P7-P6).
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