Valve pump

A combined purge pump and sample pump comprising:

• an enclosure;
• means for applying gas under pressure to the enclosure;
• pump inlet means for permitting the flow of liquid under ground from a well into said enclosure;
• said pump inlet means including first check valve means whereby liquid is permitted to flow into said enclosure but not permitted to flow out of said enclosure;
• and conduit means for permitting liquid to flow out of said enclosure as gas is applied to said enclosure;
• said conduit means including a conduit-means inlet portion;
• said conduit-means inlet portion including liquid level sensing means for permitting liquid to flow from the enclosure into said conduit means when a substantial amount of liquid is within said enclosure;
• said liquid level sensing means including second check valve means having a valve element, a valve seat and a valve housing;
• said valve element having a density less than said liquid but more than said gas, whereby said valve element floats free of said valve seat in the presence of said liquid but not in the presence of said gas;
• said conduit-means inlet portion including a conduit-means inlet opening and a third check valve means for permitting liquid to flow into said conduit means;
• said conduit means extending between said enclosure and the surface of the ground;
• a bladder pump communicating in series with said liquid level sensing means, said bladder pump including a conduit for applying gas thereto, an expandable bladder and an outer casing wall extending laterally from said liquid level sensing means;
• said valve element including:
• a nose part fitting within said valve seat;
• a valve opening communicating with said conduit means and said valve housing;
• a valve housing inlet opening communicating with said enclosure and said valve housing wherein water and gas may flow from said enclosure into said valve housing;
• the distance between the walls of the valve housing and valve element being between 8 thousandths inch and 1/4 inch;
• said valve housing inlet opening, valve opening and valve element being arranged with respect to each other so that the valve element is lifted sufficiently by the liquid before said valve element nose leaves said valve opening to avoid venture effects from liquid flowing past the valve element between said valve housing inlet means and said valve opening;
• said conduit-means inlet opening connecting said firs check valve means and third check valve means wherein negative pressure between said second check valve means and third check valve means may pull said first check valve means from its valve seat whereby pressure is released that otherwise would tend to hold said first check valve means and third check valve means closed.