Question 2: Can a gear pump "lift" liquid? What is dry lift?
Answer:
Yes. Gear pumps have good lift characteristics, in the range of 5-20 feet, depending on the particular design. Lift characteristics of a gear pump improves significantly if even a minute amount of liquid is initially allowed to "wet" the internals, which is often the case if a pump was tested at the factory, and some residual liquid remains, or intentionally pre-lubed at the site. This minute amount of liquid acts as a capillary barrier in the clearances, preventing air from escaping back to suction during startup at lift. With no pre-lube, gear pump will still lift, but not as good.
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