Do you have a suction pump higher than 9 meters?
This screw self-priming pump suction process can be more than ten meters or more, my family is using this
Pump rated suction generally 7 meters or so, it is estimated that no one calibration pump suction stroke 9 meters. Calibration suction range of 9 meters is not reliable.
Since the atmospheric pressure has been basically determined, the theoretical suction degree of the pump is more than 10 meters.