When designing and constructing a hydraulic tank there are a lot of things to consider. One of them is to ensure an air-sucking vortex (like that you see when water goes down a drain) can not develop at the pump intake line penetration. Doing the following will ensure that it doesn't:
- Locate the intake penetration at least five times its inside diameter from the nearest reservoir wall, and no less than half its inside diameter, (but at least 100 mm or 4"), off the bottom.
- Ensure the intake penetration always remains submerged by at least twice its inside diameter.
- Size the intake line so that fluid velocity is no more than 1.2 m/sec (4 ft/sec), and preferably slower.
- Terminate the intake penetration inside the tank with a bell-mouthed adapter or flared tube. This reduces fluid velocity at the point of entry. It also tends to minimize turbulence which results in quieter pump operation.
- On flooded inlets, install a vertical baffle along the intake penetration's center line. (To check the effectiveness of this technique, pull the plug on a sink of water, wait for the vortex to develop, and then watch what happens when you insert your experimental baffle!)
Bottom line: air is a contaminant of hydraulic fluid and allowing it to get into a hydraulic system can have serious consequences. And to discover six other costly mistakes you want to be sure to avoid with your hydraulic equipment, get "Six Costly Mistakes Most Hydraulics Users Make... And How You Can Avoid Them!" available for FREE download here.