CORE BARREL VALVE ASSEMBLY

摘要

A valve assembly for use in an inner tube member of a core barrel head assembly positionable within a drill string of a drilling apparatus. The valve assembly works using two separate surfaces and a biasing element with a force Fs. When hydrostatic pressure is present forces are created on these surfaces, these forces have a direct relationship with pressure, as an increase in pressure will increase the force and vice versa. The surface areas are designed such that the valve will maintain closed while under a predetermined fluid pressure, indicating to the driller that the inner tube has landed. When the driller relieves the fluid pressure and the pressure decreases, the force difference between the respective forces decreases until the valve opens for drilling through the force from the biasing element.