Hydraulic Flow Control MECH1300 Topics Flow Control Valve Types Flow Coefficient Circuits Cushioned Cylinders Flow Dividers Flow Control Valve Specifications

Flow Control Types MECH1300 Metering – Controlling the flow rate Meter In – IN to OUT is the controlled direction, OUT to IN is uncontrolled (Controls the flow IN) Meter Out – OUT to IN is the controlled direction, IN to OUT is uncontrolled (Controls the flow OUT)

Flow Control Types MECH1300 Needle valve - An adjustable orifice that can be closed to reduce the flow rate. Referred to as metering valves Often used as a manual shut off Flow is controlled in one direction only Referred to as Flow Control valves when they have an integral check

Flow Control Types MECH1300 Pressure Compensated valve – Automatically adjust the size of the orifice in response to changes in system pressure. Uses a spring loaded compensator spool that reduces the orifice size when upstream pressure increases Temperature compensated valves – orifice decrease as temperature increases

Flow Coefficient MECH1300 Flow coefficient describes the exact relationship between pressure drop and flow rate

Flow Coefficient MECH1300

Flow Coefficient MECH1300

Metering Circuit MECH1300

Circuits MECH1300 Pressure Intensification – Occurs in cylinders if the flow control valve is completely closed. The cylinder won’t move and pressure builds up. (happens with meter out fcv’s). A disadvantage of metering out. Tractive Loads – Loads that act in the direction of movement. Resistive Loads - Loads that oppose the direction of motion. Bleed Off – An additional line is run through a flow control back to the tank. To slow down the actuator, some of the flow is bled off through this line.

Cushioned Cylinders MECH1300 Used when it is desired to slow a cylinder down just before is reaches the end of its stroke. Helps prevent a clamp from doing damage to itself or a work piece.

Flow Dividers MECH1300 Divide the flow from a pump into two or more streams of equal flow rates Balanced Spool Rotary

Flow Control Valve Specifications MECH1300 What to look for: Max Pressure, Max Flow, Filtration level, Fluid type, Size, Mounting and porting