Patent ID: 7070394

Claim:
A gas pressure driven fluid pump, said pump comprising: a source of pressurized gas; a pump tank having a liquid inlet and a liquid outlet; a float carried within the interior of said pump tank, said float being operable to move between a low level position and a high level position; an exhaust valve in fluid communication with said pump tank, said exhaust valve capable of switching between an open position and a closed position; a motive valve in fluid communication with said pump tank, said motive valve being separate from said exhaust valve and capable of switching between an open position that allows fluid communication with the source of pressurized gas and a closed position that prevents fluid communication with the source of pressurized gas; a pilot valve operatively connected to said float and controlling operation of both said exhaust valve and said motive valve, said pilot valve operable to switch said exhaust valve to said open position and said motive valve to said closed position when said float falls to said low level position and to switch said exhaust valve to said closed position and said motive valve to said open position when said float rises to said high level position, wherein said pilot valve is operative to supply a motive valve pilot signal to said motive valve when said float reaches said low level position and is operative to supply an exhaust valve pilot signal to said exhaust valve when said float reaches said high level position; and whereby liquid filling said pump tank causes said float to rise from said low level position to said high level position when said exhaust valve is open and liquid exiting said pump tank causes said float to fall from said high level position to said low level position due to introduction of the pressurized gas when said motive valve is open.