The main difference between a safety valve and a relief valve is their scope of operation at the set point pressure. A safety valve normally opens up just as needed to relieve the overload condition. In contrast, a safety valve may open even when the pressure is very low. Relief valves are used to relieve any or all of the pressure when the load condition is satisfied. Thus, they are used for such purposes as controlling or relieving the load in power-generating equipment or for controlling the flow of fluid through an irrigation system.
There are many ways to prevent accidents in the process industry. One way is to prevent the gas from escaping at a set point. Another way is to prevent the gasses from coming back into the vessel. One such safety valve or regulator is a safety valve and relief valve combination. It combines the features of both safety valves and relief valves to provide a fully automatic and self-regulating mechanism.
A safety valve and relief valve combination is commonly used in steam and water pipes to prevent and relieve the steam pressure and high temperature gasses. Steam is usually used for interior systems while water is used for exterior systems. The two types of safety valve and relief valve combine both features of valves to provide a fully automatic regulation solution. They are also commonly used in various applications in the power industry. The commonly used safety valve or regulator is the high temperature interrupter.
High temperature interrupters are specially designed to operate within a steam-pressure environment. They can be used on any pipe or equipment where high temperatures are needed to keep equipment or machinery under control. High temperature interrupters are available in the market in different design and sizes. Most commonly used high temperature interrupters are the standard safety valve and relief valve combination. They are widely used in the power industry for controlling steam, gas and industrial steam pressures.
Standard safety valve and relief valve combinations have a safety switch that controls the interrupter. This safety switch is normally located above the piston so it can easily be reached by the workers. When a high temperature condition is detected, the safety valve automatically opens and the steam pressures are released through the two paddles. The two paddles rotate and move up and down until the desired pressure is achieved. When the paddle is rotated in the opposite direction, the pressure is released from the steam tube.
The steam safety valves and relief valves are available in different types and configurations. The most common steam safety valve and relief valve configuration are the ball and sleeve combination. Different types of these valves have different configurations as well.
A ball-and-sleeve combination is designed to provide both positive and negative pressures. The pressure relief of this system can also be variable. There are a primary relief tube, which have a positive pressure controlled by the ball, and a lower relief through a safety valve. The main difference valve prevents the fluid loss by closing off the lower relief tube.
A direct-loaded safety valve regulates the flow of fluid directly. It has a piston and two sleeves that allow only fluid or gaseous substances to pass through. In order to work, the valve must be open. There is a needle, which is placed at the top of the valve, that allows only a small amount of fluid or gas to pass. When the needle is pushed up, the flow of the fluid is restricted and when it is pushed down, the flow is unrestricted.