Water contains approximately 2% air by volume. When it is being pumped, some of this entrained air will separate out of the water and accumulate in system high points. Air can also enter into the pumping system through common leak paths such as shaft seals, leaky joints, or open ports. If this air is not removed, it creates a restriction that reduces pumping efficiency, increases power consumption, increases fluid velocity, and promotes corrosion. If left unchecked, this can cause a pump to become air-bound so it cannot start, or even lose its prime during operation.
A Q-VAC priming system eliminates these issues so that every pump is kept fully primed. This is accomplished by installing a float-actuated priming valve as the high point in the suction piping. When air collects in the priming valve, the level sensitive float drops which opens the priming valve to the priming system. The air is then immediately removed which causes the water level inside the priming valve to be restored, and the float rises to close the priming valve. Since the priming system maintains a deeper vacuum than what is required to simply prime the pump, the priming valve can open and close many times to remove accumulated air without causing the Q-VAC system to run. As this process continues, the vacuum level of the priming system is gradually reduced until a control setpoint is reached and a vacuum pump turns on to restore a higher vacuum level.
Continuously removing air from the suction piping to maximize pump efficiency and ensure continuous pump prime is another major benefit of Q-VAC priming systems.