What is the Difference Between Safety Valve and Relief Valve?
🆚 Go to Comparative Table 🆚The main difference between a safety valve and a relief valve lies in their purpose, operation, and setpoint. Here are the key differences:
- Purpose:
- Safety valves are designed to prevent accidents by preventing system pressure from getting too high. They protect people, property, and processes from catastrophic overpressurization events.
- Relief valves are designed to control pressure in a system, often in fluid or compressed air systems, and protect components from excess pressure.
- Operation:
- Safety valves open when the system pressure reaches a certain point, releasing excess pressure to prevent an accident.
- Relief valves open in proportion to the increase in system pressure, gradually allowing the system to return to the preset pressure level.
- Setpoint:
- Safety valves start opening when pressure is three percent higher than their setpoint.
- Relief valves start opening when the pressure is 10 percent higher than their setpoint.
In summary, safety valves are more commonly used in thermal systems and vessels that can build up pressure, such as those involving gases, hot fluids, and chemicals. On the other hand, relief valves are more commonly used in liquid systems, where a gradual release of pressure is more appropriate. Although both valves serve similar functions, they are not interchangeable and are used differently depending on the specific needs of the system.
Comparative Table: Safety Valve vs Relief Valve
The main difference between safety valves and relief valves lies in their primary functions and applications within a pressurized system. Here's a table comparing the two:
| Feature | Safety Valve | Relief Valve |
|---|---|---|
| Purpose | Designed to protect people, property, and processes from catastrophic overpressurization, often as a last resort when other relief valves fail. | Designed to control pressure within a system, most often in fluid or compressed air systems, by opening in proportion to the increase in system pressure. |
| Function | Opens fully when a system becomes overpressurized, providing a rapid release of pressure. | Opens gradually, allowing the system to return to the preset pressure level, and closes when that level is reached. |
| Application | Acts as a last line of defense against unsafe conditions, protecting facilities from damage and ensuring safe operation. | Helps avoid system failures and protects equipment from overpressurized conditions. |
Both safety valves and relief valves are designed to release pressure from a pressurized system when it becomes overpressurized. However, safety valves are typically considered the last line of defense, providing a rapid release of pressure when all other relief valves have failed. In contrast, relief valves are designed to control pressure within a system, opening gradually to allow the system to return to the preset pressure level.
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