As water is drawn from its various sources and flows through a city's complex maze of water mains and service lines and into homes and buildings, there are hundreds of water control devices at work. A combination of gravity and pumps produces the pressure that makes the water flow, and dozens of types of valves and regulators efficiently and safely direct and control the water. Among the types of valves used are ball valves, gate valves, check valves and temperature pressure relief (TPR) valves.
Every home and building should be equipped with at least one water pressure regulator. As the name suggests, this water safety device regulates the pressure in the water line. The regulator ensures that a system has sufficient pressure but keeps the pressure low enough to avoid damaging pipes and appliances.
Ball valves are among the simplest water control devices available. These valves are usually made of bronze and designed in a straight-through fashion. Inside the valve is a steel ball with a hole bored through the center. There typically is a straight handle on the valve body which, when turned, rotates the ball so that it either blocks the water or allows it to flow through the bored hole.
The gate valve is one of the most familiar water control valves. A gate valve is what is typically used as a water valve, or spigot, on the outside of a home. Like check valves, gate valves generally are made of bronze. Instead of a ball, the gate valve uses a plate as its water control device. Water flow is controlled by turning the knob on the valve, which raises and lowers the plate inside.
Check valves are used to control the direction of flow. Sometimes called one-way valves, these water control valves have a spring and ball, or poppet, in the center that keep the valve closed. When there is enough water pressure, the valve opens, allowing the water through. When the pressure is lowered, the check valve closes again. Check valves are often used in irrigation and sprinkler systems to keep the pipes from draining when the water is shut off.
TPR valves are used as safety valves on hot water heaters. If the temperature or pressure in the tank exceeds safe levels, the TPR valve opens to release water. This lowers the internal pressure and allows cold water into the tank, which also lowers the temperature. Without a properly functioning TPR valve, a water heater could easily overheat or accumulate too much pressure, which could result in a catastrophic explosion.