Float operated pneumatic pump

摘要

A float operated, top fill, recovery unit floats in a body of contaminated groundwater to recover a layer of liquid hydrocarbons residing on top of the groundwater. The recovery unit has an upper end fitted with a discharge check valve assembly and a lower end that is closed, the discharge valve assembly including a semi-permeable screen which is positioned in and skims the liquid hydrocarbons, and a series of passages and check valves for directing the hydrocarbons via a return line to a holding tank. In an embodiment disclosed, the lower end of the unit is formed in part by an inlet check valve arrangement which has had its check ball removed such that the arrangement does not operate to inhibit flow, and a closure plate is secured to the inlet valve arrangement to prevent external fluid from entering the unit. Sinking of the recovery unit allows hydrocarbons to pass through the screen to fill the interior of the unit so that it can be pumped out of the unit by compressed air and conveyed to the holding tank. The top fill recovery unit is easily modified to a bottom fill underground contaminated water recovery unit by removing the closure plate and replacing the check ball in the inlet valve arrangement, removing the top discharge valve assembly, and connecting the return line directly to the top of the unit.