Hydrostatic line testing and method

Claim 1

Apparatus for testing whether a pipe which is closed at one end and filled with a first liquid, such as gasoline, having a first predetermined density is leaking comprising: means coupled to the opposite end, opposite said one end, of said pipe for applying pressure to said first liquid in said pipe comprising an upstanding cylinder containing a second liquid having a density equal to said first predetermined density of said first liquid; means for coupling one end of said cylinder to said opposite end of said pipe so that the liquid in said cylinder is in intimate fluid contact with said first liquid in said pipe to be tested; means for admitting a third liquid to the opposite end of said cylinder; said third liquid having a density substantially different than said first predetermined density such that said second and third liquids, although in intimate contact with each other at a junction in said cylinder, remain substantially separated at said junction and substantially do not mix; means for applying a predetermined pressure to said third liquid in said cylinder in a direction tending to force said second and third liquids in said cylinder toward said first liquid in said pipe; and graduation means on said cylinder for providing a visual indication whether said junction of said second and third liquids in said cylinder moves toward said first end or said second end of said cylinder and thus indicate volumetric changes of the first liquid in said pipe being tested.

Claim 11

A method of testing whether a hollow cylindrical conduit, which transfers liquid, such as gasoline, of a predetermined density, from an underground storage tank is leaking, comprising: isolating a downstream end of said conduit to be tested from said underground storage tank; communicating a first liquid, substantially identical to the liquid in the conduit being tested, to one end of said conduit being tested via one end of a graduated cylinder; communicating a second liquid, having a second predetermined density which is substantially different than said predetermined density, to the opposite end of said graduated cylinder, so that said first and second liquids are separated at the boundary thereof; applying an above atmospheric pressure to said second liquid tending to force said first liquid into said line to be tested; and visually determining volumetric changes of the liquid in the line being tested by visually determining whether the boundary of said first and second liquids moves along the length of said cylinder.

Claim 12

A method of testing whether a hollow cylindrical conduit, which transfers liquid, such as gasoline, of a predetermined density, from an underground storage tank is leaking, comprising: isolating a downstream end of said conduit to be tested from said underground storage tank; communicating a first liquid, substantially identical to the liquid in the conduit being tested, to one end of said conduit being tested via one end of a graduated cylinder; communicating a second liquid, having a second predetermined density which is substantially different than said predetermined density, to the opposite end of said graduated cylinder, so that said first and second liquids are separated at the boundary thereof; applying an above atmospheric pressure to said second liquid tending to force said first liquid into said line to be tested; and visually determining volumetric changes of the liquid in the line being tested by visually determining whether the boundary of said first and second liquids moves along the length of said cylinder.