Abstract: A valve assembly especially adapted for use with very high pressure reciprocating pumps. The main components are coaxially aligned. A main high pressure passage extends through the center of the assembly and has check valves at opposite ends thereof. One of the check valves has an annular valve element comprising inner and outer sleeves which fit against one another with an interference fit. This annular valve element seats against a matching annular inlet passage.

Abstract: A high velocity, constant flow, liquid jet cutting apparatus comprising a source of high pressure fluid, a jet nozzle, and a high pressure conduit to carry the fluid from the source to the jet nozzle. Immediately upstream of the jet nozzle is a liquid collimating device comprising a housing interconnected between the conduit and the nozzle and defining a flow collimating chamber directly upstream of the nozzle, through which the high pressure liquid is delivered to the nozzle. The cross sectional area of the flow collimating chamber is at least greater than 100 times the cross sectional area of the nozzle opening, and desirably in the order of four hundred times as great or more. The resulting liquid jet has relatively little dispersion of the liquid and is capable of effectively cutting a relatively narrow kerf with a high quality finish and little, if any, wetting.