Needle type flow control valves can be installed in hydraulic system pressure lines to provide infinitely variable flow control.

Needle type flow control valves manufactured by Hydraulic System Products can be installed in hydraulic system pressure lines to provide infinitely variable flow control. Two versions are available: the Model HSP2810 allows infinitely variable controlled flow in either or both directions; the Model HSP2818 has an integral check valve to allow infinitely variable controlled flow in one direction and free flow in the opposite direction. In both models the flow rate is varied by a tapered valve which passes through a fixed orifice.

A threaded stem with a hand wheel controls the height of the valve and a locknut is provided on the threaded stem to lock the flow setting.

The valves are designed for in-line mounting and each model is available in four sizes having port connections of 0.25, 0.375, 0.5 and 0.75in NPTF or BSPF.

The largest sizes offer variable controlled flows up to 80 litre/min.

The check valve on the Model HSP2818 has a cracking pressure of 0.20bar and permits free flow up to 110 litre/min for the largest size.

Maximum operating pressure is 350bar for all valves.

The steel bodies are zinc plated and passivated for maximum protection against environmental conditions and the stem is stainless steel with Viton seals.

Overall height with the stem fully open is 104mm for the largest sizes of both models.

Lengths port to port for the largest sizes are 72 and 90mm for models HSP2810 and HSP2818, respectively.

Typical applications would include limiting the maximum speed of a cylinder movement in either meter-in and/or meter-out circuits or in a test rig to apply infinitely variable and progressive back pressure on the test piece.