Plumbing Valve Types
There are a number of different plumbing valves used to control the flow of water in a building. The pros and cons of each type are identified below.
Ball Valve
Ball valves are made with a rotating sphere that has a hole in it. In the open position, the hole in the sphere is in line with the pipe. When closed, the hole in the sphere is perpendicular to the pipe. The lever handle operates the valve, but also serves as an indicator for whether the valve is open or closed. When the lever is parallel to the pipe, the valve is open.
Ball valves do not allow for precise flow control because they usually have positive stops (0, 45, 90 degrees), but they do provide a very good seal in the closed position.
Gate Valve
Gate valves control water flow by raising or lowering the gate, which is generally a piece of metal. There is a wheel or knob at the top of a gate valve that controls the height of the gate - this, in turn, affects the flow of water. Unfortunately, the wheel doesn't provide any indication of whether the valve is open or closed, or to what extent.
Gate valves provide a reasonable seal, but they should not be used to adjust flow - they should be open or closed. Gate valves may not be very durable and are susceptible to corrosion, which will cause the valve to get stuck in the open or closed position.