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Gate Valve Disc Positions
Please refer to the figures shown above.
The figure on the right hand side shows a gate valve with its disc in full down (closed) position.
The figure on the left hand side shows the gate valve in full open position. Notice, in the open position, the disc has been pulled totally out of the way of the fluid flow. This is so because the disc should be subjected to flowing fluids as little as possible. Obviously, when the valve is being opened or closed it will cause the disc to come in contact with flowing fluid for a short time.
Also, notice that the disc in this case is one solid piece. This type of construction is referred to as the “solid wedge construction.”