The effect of negative pressure on bellows mechanical seals
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Does anyone know the impact of negative pressure on bellows seal systems? At the start of operation, when there is negative pressure in the system and the pump inlet valve is suddenly opened to fill the pump, a negative pressure is created inside the pump chamber – could this cause damage to the bellows? The absolute pressure is 10–30 KPA
It’s okay; we use a bellows seal for this, as it’s a high-temperature medium!
What causes cracks in the graphite ring between the stationary and rotating rings?
There’s definitely an impact; I’ve seen many new units experience pump cavitation while in operation, with the static ring shifting out of position and resulting in seal leakage
This amount of negative pressure should be fine; we also use it in applications with negative pressure!
I just understood your question. What you mean is that due to the negative pressure condition, the pump gets evacuated, and cracks appear on the dry friction pair of the mechanical seal – that’s what it means! Negative pressure isn’t a problem, but dry grinding under vacuum is definitely not acceptable! !