1. Field of the Invention
This invention relates to a valve provided for a branch pipe connected to a main pipe, and more particularly to a valve having a function that prevents liquid from stagnating in the branch pipe and the valve when the valve is closed.
2. Description of the Related Art
In order to collect ultra pure water flowing through a main pipe of a ultra pure water production line used, for example, in the semiconductor industry, a branch pipe is connected to the main pipe and a valve is provided for the branch pipe so that ultra pure water is collected from the main pipe by opening the valve.
FIG. 1 is a view showing an example of a conventional water collecting or sampling (hereinafter referred to as collecting) valve attached to a main pipe.
In FIG. 1, reference numeral 20 denotes a main pipe, 21 denotes a branch pipe connected to the main pipe 20, and 22 denotes a valve attached to an end portion of the branch pipe 21. In a conventional collecting valve, when the valve ball 23 in the valve 22 is opened, ultra pure water flowing in the main pipe 20 is introduced into a passageway 25 in the valve case 24 and into a flow passageway 26 provided in the valve 23 to allow to collect ultra pure water from the end opening 27 of the valve case 24.
In order to collect ultra pure water flowing in the main pipe 20 to the outside as described above, a valve 22 is provided for the branch pipe 21 connected to the main pipe 20, which valve can be opened or closed.
However, in the case of a valve of the conventional structure, when the valve ball 23 is closed, ultra pure water will stagnate in the branch pipe 21 and passageway 25 in the valve case 24, thereby allowing bacteria to proliferate or small particles to be deposited. Upon resuming the water collection, the stagnant water containing these contaminants will flow out first, and accordingly, there is a problem in that ultra pure water collected must first be blown down and discarded.
What is worse, the stagnation of ultra pure water has an adverse effect upon ultra pure water which flows through the main pipe 20.
Therefore, the present invention has been made to eliminate the problems of valves of the conventional type described above, and it is an object of the present invention to provide a valve with a function to prevent the stagnation of liquid so as to prevent proliferation of bacteria and deposition of small particles by constructing the valve such that, even when the valve is closed, the liquid does not stagnate in the branch pipe nor in the valve but is allowed to flow continuously therein.