What's a flash point?


Thread Starter

Betty Lee

I'm reading one of the articles on your website, and in there it mentions a liquid "is very close to its flash point with regard to pressure drop in the pipe line", does flash point mean melting point?
does flash point mean melting point?
No. liquids can't 'melt'. Flash-point means the point at which the (usually) liquid converts to a gas, usually involving massive increases in required volume and may involve exothermic or explosive reactions.
Flashing is the transitory state between the liquid phase and the gas phase. The molecules lightly bound expand first, but somewhat constrained by the surronding ones.

In valve dynamics, as the fluid vein contacts by the restriction created by the 'plug', the pressure decreases at that contraction (energy conservation principle : Bernoulli). The decrease in pressure may reach near the boiling point, then flashing exist first. Further down the vein, pressure recovers and flashing bubbles collapse.
This situation is not damageable.
Smooth constant noise like light wind.
If the pressure recovery is insufficient,i.e: too high pressure drop across the entire valve, then the fluid enters boiling phase. Bubbles instead of implosing, explode with extreme force to extract metal molecules where they hit. That phase is cavitation (like in pumps).The noise is gravel passing through the pipe. Your valve will be soon deceased.
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