Self-Priming Sealless Canned Motor Pump is used for pumping fluids from underground tanks and for rail / rank truck unloading. The Self Priming Pump is designed to lift water from some level below the pup suction without having to fill the suction piping with liquid. If accomplishes this by creating a partial vacuum at the pump suction which removes the air from the suction line. The pump then release the entrained air through its discharge while retaining the initial fill of water in the pump case. This air/ water separation is what makes the self-primer different.