『Flow Control Valve Meter In and Meter Out Configurations for Hydraulic Cylinders』Related information(flow rotameter|digital flow meter|balo meter|hydraulic flow meter|volumetric meter|positive displacement meter|pitot tube flow meter|displacement meter|cfm meter|variable area flow meter|inline flow meter|differential pressure flow meter|calibrated flow meter|velocity meter|paddle wheel flow meter|oval gear flow meter|anemometer hvac|multiphase flow meter|doppler flow meter|thorpe tube flowmeter|heat flow meter)
Flow Control Valve Meter In and Meter Out Configurations for Hydraulic Cylinders
Quick Answer: A meter in configuration controls oil flow before it enters a hydraulic cylinder. A meter out configuration controls oil flow after it leaves the cylinder. For pushing loads, meter in works. For overrunning or vertical loads, meter out gives better speed control and stability. Silver Instruments recommends an oval gear flow meter such as the OGF series for verifying flow in these circuits.
Meter In Configuration in Plain Terms
Meter in means the flow control valve sits on the inlet side of the cylinder. Pump flow passes through the valve before it reaches the bore or cap end. The valve restricts supply flow. The cylinder moves slower because less oil enters per minute.
This setup is common on press feed cylinders, clamping systems, and machine tool slides. For example, a plywood press in Indonesia uses a meter in valve on the cap end. The system runs at 110 bar and 6 L/min. The operator sets the throttle once per shift.
Meter in works well when the load resists motion. A drill feed, a lift against gravity without a lowering function, or a paper roll nip load can use it. The cylinder back pressure stays low. Heat rejection is simple because the pump relief flow does not pass through the cylinder.
But there is a drawback. If the load pulls the piston rod faster than the supply flow, the cap end can cavitate. The rod end may not build enough back pressure. We have seen this on a plastic injection mold clamp in Mexico. The mold opened with a negative load and the cylinder jumped. The fix was a meter out valve.
Meter Out Configuration in Plain Terms
Meter out means the flow control valve sits on the outlet side of the cylinder. The valve restricts oil leaving the rod end or cap end. The cylinder speed depends on how fast oil can exit.
This setup works better for overrunning loads. A vertical lift, a crane boom lower, or a hydraulic winch can pull the piston. The meter out valve creates back pressure in the return line. The cylinder moves with more control. A port maintenance team in Chile uses a meter out valve on a boat lift platform. The platform lowers at 2.5 L/min on DN10 hose.
In practice, most engineers choose meter out for mobile and marine equipment. The return side restriction also keeps pilot operated check valves seated until the pump sends flow. That prevents load drop during startup.
The tradeoff is heat. The outlet restriction turns energy into heat. A 20 bar pressure drop at 15 L/min rejects about 0.5 kW as heat. That is manageable on small systems but needs a cooler on continuous duty circuits.
How to Choose Between Meter In and Meter Out
Here is the thing. Look at the load direction first. If the load always pushes against the cylinder, meter in is enough. If the load can run away or overrun, use meter out.
Check the cylinder area ratio. A 2:1 rod cylinder has lower rod end volume. The same pump flow creates different rod end velocity. Meter out flow is smaller than meter in flow for the same cylinder speed because of the rod area. Size the valve for the return flow, not only the inlet flow.
For circuits that need both directions under negative load, use a meter out valve on each port. Or use a counterbalance valve together with a flow control valve. A hydraulic drill rig in Ghana had a rotary head that dropped too fast on retract. A meter out valve with a 5 bar spring setting fixed the issue.
Where Flow Measurement Supports Hydraulic Cylinder Control
A flow control valv
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Most engineers skip this part. They trust the valve setting but do not measure actual flow. A customer in Vietnam asked us last year for a meter to check a hydraulic press circuit. The valve was set at 12 L/min but the oval gear meter read 9.8 L/min because the pump was worn. That 2.2 L/min gap explained a slow cylinder cycle.
Silver Automation Instruments supplies oval gear flow meters for hydraulic oil. The OGF series works from DN10 to DN25, with 4-20 mA HART output and pulse output. Typical ranges are 0.3 L/min to 150 L/min. Maximum pressure options reach 350 bar depending on the connection. These meters fit hydraulic power units, test benches, and brake circuits.
For a cylinder circuit running at 30 L/min, a DN15 oval gear meter is often enough. The meter body uses cast iron or stainless steel. Wetted parts match hydraulic oil with viscosity from 1 cP to 1000 cP. Temperature spans from -20°C to 120°C.
Flow meter data also helps tune a proportional directional valve. You can adjust the valve command until the meter reads the target speed in L/min. That method is faster than timing the cylinder with a stopwatch.
Recommended Models from Silver Instruments
OGF oval gear flow meter: Use for hydraulic oil, lubrication oil, and diesel. DN10, DN15, DN20. Accuracy 0.5% of reading. Output 4-20 mA HART and pulse. Pressure rating up to 350 bar with NPT threads. Good for meter in and meter out circuit verification.
Coriolis mass flow meter: Use for test benches that need mass flow or density data. The meter gives kg/h, density, and temperature. It works well for high viscosity hydraulic oil and does not need straight pipe runs.
Turbine flow meter: Use for clean low viscosity fluids in return lines up to 250 bar. This model is lower cost for simple pump flow tests. Pair it with a display unit for local reading.
Send us your pressure in bar, temperature in °C, pipe size in DN, and flow range in L/min. We will recommend a meter for your hydraulic cylinder circuit.
Contact Silver Automation Instruments
Tel: +86-25-68650347
Whatsapp: +86-25-52155837
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FAQ
Which valve configuration is better for a vertical hydraulic cylinder?
Meter out is usually better. The outlet restriction holds back the rod and prevents the load from dropping too fast. Use a counterbalance valve if the load is heavy.
What flow meter works with hydraulic oil at 250 bar?
A stainless steel oval gear flow meter from the Silver Instruments OGF series works at 250 bar and above. DN15 covers most flows from 0.5 L/min to 30 L/min.
Can a meter in valve control a negative load?
No. A negative load pulls the cylinder faster than the supply flow. The cap end can cavitate. Use meter out or a counterbalance valve for negative loads.
What pipe size should I use for a 30 L/min hydraulic circuit?
DN15 or DN20 is common for 30 L/min. Pressure drop depends on hose length and oil viscosity. We can calculate the pressure drop if you send your oil grade and temperature.
Does Silver Automation Instruments supply flow meters for hydraulic test benches?
Yes. We supply oval gear, Coriolis, and turbine flow meters for hydraulic test benches. Tell us your flow range and mounting port size. We will provide a product data sheet and price.
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