One problem that plumbers deal with on a regular basis is the replacement of old shutoff valves. When installing or replacing a shutoff valve, you are faced with a choice: ball valve or gate valve?
Since water inherently wreaks havoc on every aspect of your plumbing system, having the proper valve in place will help “delay” problems down the road. I use the term “delay” instead of “prevent”, simply because when it comes to plumbing, problems will ALWAYS arise, it’s just a matter of how soon. The gate valve has been around longer, and is slowly becoming obsolete. The design of the ball valve makes it vastly superior to the gate valve, and is proven to last longer and cause less problems. A ball valve utilizes a sphere with a hole in it to control flow. When the handle is turned parallel with the valve, the hole is open to flow. When the handle is turned a 1/4 turn, the sphere is also turned and the hole is now perpendicular to the valve and flow is stopped. Ball valves can almost always be operated after years of disuse and do not typically “freeze” in position. A gate valve utilizes an internal gate that moves up and down on the stem. The stem is connected to the handle, which screws the gate up or down, opening and closing the gate. The gate valve has a few disadvantages. The biggest problem is that over the course of time, the stem, which controls the gate, may, and usually will break. This means the gate is stuck in place, and the water will either be stuck on or stuck off. Another problem is that gate valves are notorious for seizing shut after a long period of non-use. If they can be freed up, they will usually start to leak. One thing you should keep in mind though, there are some areas that actually still require the use of gate valves before and after the water meter. The reason being that a ball valve can be shut off very fast with just a quarter turn, whereas a gate valve is not. In the VERY unlikely event that all the water is running in a house, and the ball valve is shut off quickly, it will cause a water hammer condition, and MAY cause a problem elsewhere. This is extremely unlikely and should not be a factor unless required by your local authority.
Another thing to keep in mind is that like all things, there are different grades of each type of valve. Unfortunately, the box stores typically only sell on price, and not quality. We have seen a great deal of defects and leaks with “economy” grade valves. A reputable plumber will always supply you with a better valve, and will also be able to install the best valve for you upon request. It is advised that if you are in an area requiring a gate valve, a good quality gate valve is a very worthwhile investment.