This is a vacuum pump which is connected to the self priming pump. It obtain to come the water though the inlet of the pump by suction air inside the pipe. When the water is filled whole pipe and the water pump run normally the vacuum pump stops. The vacuum pump is the pump which has double eccentric pistons, first suck the air then water and discharge them from outlet which is settled both side. The vacuum pump that it's power by the triggel pulley which is connected to other on the pump shaft. The magnetic clucth on the vacuum pump's shaft is locked triggel pulley and transfer the movement of the pump shaft to the vacuum pump. In the same way, it releases the triggel pulley when the electric supply is cut off and turns freely. The magnetic clucth is feeded with 24 VDC. When the pressure increases in the outlet of the pump runs freely, the parts which is constituted the vacuum pump is made by aluminum of brass. So they prevent the pump from rust. The vacuum pump is used long term without any problem and their maintenance period is long.