Abstract: A pump for pumping fluid down a well bore in a rock formation comprises: intake and discharge passages; a pumping chamber with a plunger therein; intake and discharge valve assemblies in the intake passage and the discharge passages. At least one valve assembly has a valve body movable into sealing contact with the valve seat by fluid pressure in the pumping chamber. The valve seat may have a cylindrical outer surface for mating reception in said intake passage, and a shoulder with a radially-projecting surface biased against a wall for sealing. A cushioning member may be interposed between the valve body and the valve seat. A seal may be interposed between said valve body and said valve seat, and configured so that between 35% and 60% of a sealing surface of said valve seat contacts the valve body.

Abstract: The apparatus measure the exhalation of a subject and stores selected data relating to the peak value of the air pressure during exhalation. The storing unit for the data stores the peak values for a plurality of time periods and the apparatus can collect a series of measurements over an extended time period. Auxiliary information and data relating to each measurement can also be stored in the storing unit. A dedicated power source may be incorporated for holding the stored information in the storing unit.

Abstract: An applanating member is provided for use in an applanation tonometer and comprises an optical element replaceably held in a tubular carrier. The element is formed as a replaceable plastics moulding with integral means for locating it in the member axially and rotationally. Such an optical element can be used disposably so as to achieve higher standards of hygiene without excessive costs.