A bleed valve includes a valve housing defining an inlet and an outlet with a flow path for fluid communication from the inlet to the outlet. A poppet head is connected to the valve housing by a primary spring and a secondary spring. The poppet head is configured for movement relative to the valve housing between: a fully open position in which the poppet head is spaced apart from the inlet to allow flow through the flow path, with the primary spring and secondary spring both expanded; a partially closed position in which the poppet head is spaced apart from the inlet but is closer to the inlet than in the fully open position, with the primary spring compressed; and a fully closed position in which the poppet head seats against the valve housing blocking flow through the flow path, with the primary spring and the secondary spring both compressed.

A bleed valve includes a valve housing defining an inlet and an outlet with a flow path for fluid communication from the inlet to the outlet. A poppet head is connected to the valve housing by a primary spring and a secondary spring. The poppet head is configured for movement relative to the valve housing between: a fully open position in which the poppet head is spaced apart from the inlet to allow flow through the flow path, with the primary spring and secondary spring both expanded; a partially closed position in which the poppet head is spaced apart from the inlet but is closer to the inlet than in the fully open position, with the primary spring compressed; and a fully closed position in which the poppet head seats against the valve housing blocking flow through the flow path, with the primary spring and the secondary spring both compressed.

One or more techniques and/or systems are disclosed for bypass flow filtering. A bypass valve filter includes at least one wall configured to engage a surface of a bypass valve and a filter surface having a plurality of openings between an inside of the at least one wall and an outside of the at least one wall. One or more openings of the plurality of openings have a first size and one or more other openings of the plurality of openings have a second size, wherein the first size is different than the second size to define different levels of filtering. The bypass valve further includes an open end configured to allow fluid flow therethrough and to the plurality of openings.

A flow control valve for use in oil well bore holes. The flow control valve includes a plurality of flow paths connected in parallel. The flow control valve operates by successively opening different flow paths, starting with a flow path that requires a reduced force to operate its inlet valve. The flow rate through the flow control valve is controlled by opening and closing different ones of the plurality of flow paths individually or in combination. A flow path that allows fluid to flow at substantially the full flow rate of the valve is provided as one of the parallel paths. A simple mechanical design using poppet valves and at least one cam is described.

Disclosed is a differential pressure valve comprising: a valve body, the valve body having at least one flow inlet and one flow outlet: at least one shutter, the shutter being movable between an open position and a closed position under a differential pressure across the valve; at least one flow passage from the flow inlet to the flow outlet; at least one biasing member configured to bias the shutter towards a closed position so as to block the flow passage through the flow inlet. The biasing member is a non-linear biasing member.

A compressor lubrication system including a positive displacement pump, a pressure relief valve assembly, and a divider block. The pressure relief valve assembly includes a housing that has an opening to the fluid distribution system and a relief passage. A conduit is connected from the relief passage to a fluid reservoir. The assembly also includes a pressure relief valve that has an open position in which fluid from the fluid distribution system can enter the relief passage, and a closed position in which fluid is prevented from entering the relief passage. A biasing element maintains a biasing force on the pressure relief valve. The pressure relief valve is maintained in the closed position when the biasing force exceeds the fluid force on the pressure relief valve and the pressure relief valve moves into the open position when the fluid force exceeds the biasing force.

A compressor lubrication system including a positive displacement pump, a pressure relief valve assembly, and a divider block. The pressure relief valve assembly includes a housing that has an opening to the fluid distribution system and a relief passage. A conduit is connected from the relief passage to a fluid reservoir. The assembly also includes a pressure relief valve that has an open position in which fluid from the fluid distribution system can enter the relief passage, and a closed position in which fluid is prevented from entering the relief passage. A biasing element maintains a biasing force on the pressure relief valve. The pressure relief valve is maintained in the closed position when the biasing force exceeds the fluid force on the pressure relief valve and the pressure relief valve moves into the open position when the fluid force exceeds the biasing force.