Pump / Selfpriming Pumps
Pumps that are partially or completely above the fluid level allow air into the suction line, which must be evacuated or displaced before the pump can move the liquid. Self-priming pumps are capable of removing air at startup before beginning its normal pumping functions.
To avoid the mixing of air and water, self-priming pumps create a partial vacuum to discharge water while also evacuating any air. It does this by combining the air and water during the priming process, forcing the air to rise and the water to sink or go down. Gravity then pulls the air-free water back into the impeller, where it mixes with the remaining air in the suction line.
This process repeats until all air is evacuated and a vacuum forms in the suction line. Once this happens, atmospheric pressure forces the water into the suction line and towards the impeller to allow pumping to begin.
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