Deep analysis of the functional differences between check valves and valves**
**From protection mechanisms to system integration strategies**
**1. Functional essential differences**
-Check Valve**
-Core function: Prevent medium backflow (passive protection)
-Trigger condition: Relying on the kinetic energy of the fluid itself to achieve opening and closing
-Typical application: pump/fan outlet anti reverse
-* * Safety Valve**
-Core function: Overpressure relief (active protection)
-Trigger condition: Mechanical opening under preset pressure value
-Typical application: Explosion protection for pressure vessels
**2. Collaborative work scenario**
In the Roots blower system, two types of valves need to be used in conjunction:
1. * * Start up phase * *: Check valve prevents gas backflow, valve monitors the pressure rise process;
2. * * Abnormal shutdown * *: Check valve blocks recoil airflow, valve releases residual pressure;
3. * * Long term operation * *: Valves serve as a defense line to prevent system overpressure caused by check valve failure.
**3. Comparison Table of Selection Parameters**
|Parameters | Check Valve | Valve|
|--------------|-----------------------|-----------------------|
|Setting criteria | Flow direction changes | Pressure threshold|
|Response time | 0.1~0.5 seconds | 0.05~0.2 seconds|
|Reset mode | Automatic | Requires manual/automatic reset device|
|Standard Specification | API 594 | ASME Section VIII|
