EMG SV1-10 Flow Selection: 16, 32 or 48 L/min?

SV1-10/16, /32 and /48 identify rated flows of 16, 32 and 48 L/min at the specified 20 bar valve pressure drop. A guiding cylinder needs more flow as target speed increases. Increasing cylinder effective area also raises flow demand.

Start with effective area and guiding speed, then check the pressure drop available during movement. Replacing /16 with /48 changes flow for a given opening; it does not automatically improve guiding accuracy.

Catalogue flows at two pressure drops

EMG data sheet DB_SV1-10_05_en lists the following values:

Descriptions of /48 as 48 L/min and approximately 70 L/min can both be correct when their pressure-drop conditions differ.

Use the values in EMG's table rather than importing another valve's rating conditions. Rated-flow numbers from different manufacturers are not directly comparable when their reference pressure drops differ.

The SV1-10/48/315/6 model guide explains pressure and overlap suffixes. Here the calculation focuses on choosing 16, 32 or 48.

Different speeds with the same guiding cylinder

Assume a guiding roller frame uses a double-rod cylinder with equal effective areas of 20 cm². With Q = 6 × area (cm²) × velocity (m/s):

Under these conditions, a slow frame does not need /48 simply for its larger rating. At 0.30 m/s, /16 and /32 cannot meet full-opening demand by increasing the electrical command.

Moving the frame 100 mm in 0.5 seconds gives an average velocity of 0.20 m/s and 24 L/min demand. If acceleration and deceleration occupy a significant part of that interval, calculate peak speed from the velocity profile rather than using the average as the upper requirement.

Use effective cylinder area. A single-rod cylinder has different areas in each direction, so calculate extension and retraction separately.

A 50 bar pump supply does not leave 50 bar across the valve

Continue with the 20 cm² equal-area cylinder. A 6000 N frame-moving force requires approximately 30 bar across the cylinder.

With 50 bar supply during movement, return near zero and line losses ignored, approximately 20 bar remains for valve metering. Use the table's 20 bar column, not its 70 bar column, to assess speed.

Higher load, return backpressure or line losses reduce the available drop further. When movement is faster unloaded than loaded, record supply, return and both cylinder-chamber pressures during the stroke.

If a previously successful 24 L/min movement suddenly slows with unchanged valve and command limit, check supply and load changes. Increase valve size only after confirming that capacity is inadequate at the actual pressure drop.

What changes when /16 is replaced by /48?

At equal pressure drop and similar opening fraction and metering characteristics, the larger option provides more flow. Existing control settings can therefore need adjustment after fitting /48.

For a common demand of 12 L/min at the 20 bar rating condition, the demand equals 75% of /16 rated flow, 37.5% of /32 and 25% of /48. A larger valve concentrates the same demand into a smaller opening range.

These are flow fractions, not electrical-current percentages to enter directly into a controller. Overlap, drive-current range and load pressure drop influence the actual command. Changes from an existing /6 overlap require more than matching the flow number.

If a larger replacement makes small corrections abrupt, inspect command scaling and centre response as well. A larger rating raises flow capacity; guiding stability still depends on the sensor, mechanism and control settings.

When the smaller option remains appropriate

If maximum frame demand is 12 L/min, the original /16 meets speed at the lowest available pressure drop, and operation is stable, there is no capacity reason to fit /48.

If a modification increases effective area from 20 to 40 cm² while retaining 0.20 m/s speed, demand doubles from 24 to 48 L/min. At 20 bar, /32 is insufficient. /48 only meets the theoretical requirement, leaving no allowance for peak movement or flow variation; check pressure and speed requirements further.

Demand substantially beyond SV1 capacity calls for reconsidering the actuator and valve arrangement rather than continually increasing current. See the EMG SV1 versus SV2 comparison.

Conclusion

For this 20 cm² cylinder at 20 bar valve drop, /16, /32 and /48 respectively cover demands of 12, 24 and 36 L/min. Select from the fastest movement and lowest available pressure drop while preserving a useful low-speed adjustment range. A smaller option that meets demand and operates stably can be the better match.