Abstract: A hydraulic cartridge valve includes a movable member and a position monitoring mechanism configured to detect the position of the movable member. The position monitoring mechanism is adapted to generate a position signal indicative of the position of the movable member. The position monitoring mechanism can be in the form of a linear variable differential transformer (LVDT).

Abstract: A hydraulic cartridge valve includes a movable member and a position monitoring mechanism configured to detect the position of the movable member. The position monitoring mechanism is adapted to generate a position signal indicative of the position of the movable member. The position monitoring mechanism can be in the form of a linear variable differential transformer (LVDT).

Abstract: A fluid sampling apparatus for use in a hole in the earth having a rigid wall and containing a fluid comprising a flexible tubular member extendable within the hole and inflatable to a diameter effective to urge the tubular member against the rigid wall. At least one fluid pump is in communication with the tubular member and the hole for transferring fluid between the tubular member and the hole whereby the tubular member is inflated as the fluid si transferred from the hole into the tubular member and the tubular member is deflated as the fluid is transferred from the tubular member to the hole. The flexible tubular member may be adapted to contain at least one instrument for sampling and measuring fluids.