A priming connection should be provided on the suction side, and a relief valve should be set from five to ten percent above the maximum working pressure on the discharge side. Under normal operating conditions with completely tight inlet lines and wetted pumping elements, a screw pump is self-priming. Starting the unit may involve simply opening the pump suction and discharge valves and starting the motor. It is always advisable to prime the unit before the initial startup to wet the screws.