Curb Valve Styles

Gate Valve Style

• The gate style curb valves are always found on older homes. The valve consists of a wedge-shaped blocking device that is screwed into a V-shaped seat to block the flow of water. The chief disadvantage of this style valve is that it takes a lot of turning, Typical keys to turn this valve are 10-feet long and sometimes longer. Not all of this length is inserted into the ground; part of the length is to make it easy to make several turns while standing upright. How far underground the curb valve boxes are buried depends on the climate. The boxes are placed far enough below ground that they will not freeze in the winter. In the tropics they may be only a foot or two below ground.

Ball Valve Style

• Ball valves consist of a ball that is turned inside a containing sleeve. The ball has a hole drilled through it so that when the ball is turned one way, water flows through the hole and a small turn -- usually a quarter turn -- blocks the water completely. The advantages of the ball-style valve is that it is a cheap, reliable valve and requires very little turning to open and close. The disadvantage is that the valve tends to leak more, and it only works on small diameter pipes. Sometimes there are several ball valves in parallel (for more total water flow) and in a series (to control leakage).

Butterfly Valve Style

• Butterfly-style valves are used with large pipes. They contain a large disk that fits snugly inside the pipe. When the disk is turned one way, it blocks the pipe entirely and the pressure tends to force it firmly closed. Turned 90 degrees, the disk offers little opposition to the flow of water, and the flow tends to keep it in this position. Butterfly valves are more expensive than other valve styles. Butterfly valves are normally only used for large industrial installations. They are still placed underground because that is where the water pipes are and that is the best place to protect from freezing. For these large valves, the controls are built into the valve and no key is needed to open or close the valve. They are still near the curb of the property -- the main turnoff must stop all incoming water -- so they are still called curb valves.