PURPOSE: To prevent chemicals from being mixed with the atmosphere, moisture or the other base substances by providing a break seal capable of being bored by a penetrator to a control valve device attached to a storage tank and for storing, supplying, metering and dispensing volatile chemicals.

CONSTITUTION: An inlet/outlet attaching part 12 is provided on a storage tank 10, and a valve adapter nut 24 is fitted to an extension part 14 with a flange 16 continuously mounted on it. A sealing gasket 22 is fastened to a metallic break seal 16 by screwing a lower valve body 28 of a valve assembly 26 to the nut 24. The valve assembly 26 is provided with an upper valve body 10 including a valve rod 42 and a valve rod operating unit having a shape of a handle 44, and a connecting flange 38 connectable to a vacuum device to be used in manufacturing a semiconductor is continuously mounted on the upper valve body 40. A penetrator 46 capable of boring the break seal 16 is fixed to the lower part of the valve rod 42, and the periphery of the valve rod 42 is surrounded with a bellows 48.