Why are check valves generally not used in low-pressure gas pipelines?
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As the title suggests, why are check valves generally not required in the exhaust pipes of blowers and ventilators?
Imagine, if the fan stops, will the low-pressure gas flow back?
The pressure drop of the check valve is too high; the pressure of the fan is too low, so it cannot push open.
Maybe so. Even if the pressure is very low, it’s still higher than the inlet pressure, right? I guess it’s because of the high backflow valve seating pressure; if the pressure of the gas exiting is low, the backflow valve cannot operate
That makes sense; I think the same way. But for things like compressors and blowers, check valves should be installed, right?
It’s not necessarily the case either; actually, using a shutdown interlock valve is more reliable.
Even if there is a backflow, the air can’t possibly cause the impeller to rotate in the opposite direction. What’s the use of adding this...
It depends on the hazards of the medium; for example, in a sulfur recovery unit, the area behind the fan is exposed to hydrogen sulfide, and backflow of this gas can be harmful to people.
Generally, fans are equipped with DAMPERS. It won’t flow back. Additionally, for toxic gases, the tightness of sealing must be taken into consideration.
The impeller will reverse direction under backflow, right?