A hydraulic priority flow divider controls how oil from a single pump is distributed between two hydraulic circuits. It divides the incoming flow into a regulated priority flow (REG) and an excess or by-pass flow (BP).

The priority flow is adjusted to provide the required flow rate to a hydraulic motor or cylinder, while the excess flow can be returned to the reservoir or used to operate another hydraulic function.

Webtec's VFD Series uses OptiFlo® adaptive pressure-compensation technology to help maintain consistent priority flow despite changes in load pressure. The RV, CK & M Series also provides pressure-compensated flow division, with additional circuit options.

A pressure-compensated priority flow divider can help maintain a consistent hydraulic motor speed even when the pump output varies.

On agricultural machinery, for example, the hydraulic pump flow may change with tractor engine speed. Without suitable flow regulation, this can cause the hydraulic motor speed to change.

Webtec's VFD Series uses OptiFlo® technology to automatically respond to changes in operating pressure, helping maintain the selected priority flow rate. The flow can be adjusted manually or remotely, depending on the model.

This helps maintain a consistent hydraulic motor speed despite variations in pump output, provided sufficient inlet flow is available.

Yes. A variable priority flow divider can enable two hydraulic functions to operate from a single pump by splitting the pump output into separate priority and by-pass flows.

For example, the priority flow can provide controlled speed to a hydraulic motor while the excess flow operates a hydraulic cylinder or another motor.

Webtec's VFD Series uses OptiFlo® technology to compensate for changing pressures between these circuits. This allows both functions to operate simultaneously, even when their loads differ, while helping maintain the selected priority flow.

This arrangement can eliminate the need for an additional hydraulic pump in some applications, potentially reducing system complexity and installation costs.

Yes. Multiple priority flow dividers can be incorporated into a hydraulic circuit to provide independently adjustable flow to several hydraulic motors from a single pump.

Each flow divider regulates the flow supplied to its associated motor, allowing its speed to be adjusted independently of the others, subject to the available pump flow and hydraulic circuit conditions.

Webtec provides example circuits using VFD Series valves in which three hydraulic motors are driven from one pump. The motors can operate simultaneously or independently.

This arrangement is useful when several hydraulic functions require different operating speeds without the need for individual pumps.
 

Pressure compensation helps maintain a consistent hydraulic flow rate when operating pressures change.

In a conventional flow restriction, changes in load pressure can affect the flow passing through the valve. A pressure-compensated flow divider automatically adjusts to compensate for these changes, helping maintain the selected priority flow.

Webtec's OptiFlo® technology uses a pressure-balanced, spring-loaded spool that responds to pressure changes at the priority (REG) and by-pass (BP) ports. The spool automatically adjusts the flow openings to maintain the required pressure differential.

This helps keep priority flow stable as operating conditions change. If the available inlet flow decreases, OptiFlo® gives preference to the priority circuit over the by-pass circuit, helping direct the available flow where it is needed most.

Selecting the correct flow divider depends on the available pump flow, required priority flow, maximum system pressure and method of control.

Webtec offers several options:

• VFD50: Compact manual flow control for lower-flow applications.
• VFD120: Manual control for medium-flow hydraulic systems.
• VFD120-E: Electrically operated flow adjustment using a remote switch.
• VFD120MD: Remote proportional flow control using an electrical input signal.
• VFD190: Manual flow control for higher-flow applications.
• RV, CK & M Series: Flow control with the option of an integral relief valve, reverse-flow check valve or compact manifold mounting.

The VFD range incorporates OptiFlo® adaptive pressure compensation to maintain priority flow under changing load conditions.

The selected valve must accommodate both the total inlet flow and required regulated flow. Port connections, operating pressure and installation space should also be considered

The maximum ratings vary between the different Webtec flow divider ranges.

The VFD50 handles a total inlet flow of up to 50 L/min (13.2 US gpm), with a maximum priority flow of 30 L/min (7.9 US gpm), at pressures up to 250 bar (3,625 psi).

The VFD120 handles up to 120 L/min (32 US gpm), with priority flow up to 95 L/min (25 US gpm). The VFD120-E and VFD120MD offer the same maximum total flow but have priority flow options up to 110 L/min (30 US gpm).

The VFD190 handles up to 190 L/min (50 US gpm), with priority flow up to 150 L/min (40 US gpm). All VFD120 and VFD190 variants are rated up to 420 bar (6,000 psi).

The RV, CK & M Series has a listed maximum rated flow of up to 114 L/min (30 US gpm) and pressure up to 250 bar (3,630 psi). The RV relief-valve variant has an additional maximum priority-flow restriction of 50 L/min (13.2 US gpm).

The correct flow-size option and associated operating limits should always be checked before selecting a valve.

Manual flow control valves require the operator to adjust the flow directly at the valve, while electrically operated versions allow the adjustment to be made remotely.

The Webtec VFD50, VFD120 and VFD190 use a clearly marked, single-turn control dial to adjust priority flow.

The VFD120-E uses an electric motor drive, allowing the operator to increase or decrease the priority flow using a remote toggle or rocker switch.

The VFD120MD provides proportional remote control through a potentiometer or analogue electrical signal, making it suitable for applications requiring integration with an electronic control system.
All three control methods provide adjustable priority flow, with the choice depending on how and where the operator needs to control the hydraulic equipment.

Yes. The Webtec VFD120-E enables the priority flow, and therefore the hydraulic motor speed, to be adjusted remotely using an electrical switch.

The valve uses an integrated electric motor drive to adjust the flow setting. It is available in 12 Vdc and 24 Vdc versions and can be operated using a toggle or rocker switch, which is not supplied with the valve.

All the required control electronics are contained within the drive assembly, removing the need for a separate electronic control box.

This makes the VFD120-E suitable for agricultural and industrial machinery where the operator needs to adjust hydraulic motor speed without accessing the valve directly.

Yes. The Webtec VFD120MD is designed for remote proportional control using several electrical input options.

Depending on the selected version, the valve accepts a potentiometer input, a 0.5–5 Vdc signal or a 4–20 mA signal.

The electrical input controls the motor-driven adjustment mechanism, allowing the priority flow to be changed remotely. This makes the VFD120MD suitable for applications where hydraulic motor speed needs to be controlled by an operator interface or electronic control system.

The valve provides a maximum priority flow of up to 110 L/min (30 US gpm) and can move from minimum to maximum priority flow in less than 10 seconds at full pressure.

The Webtec VFD120MD is designed to retain its valve setting following a loss of electrical power.

This means the selected flow-control position is not reset simply because the power supply is interrupted. The valve also incorporates automatic current limiting to help protect the motor drive against overheating and overload.

The VFD120MD operates from an 11–28 Vdc supply and requires external electrical protection using a 2 A fuse. It is designed to meet IP66 protection with the cable connected.

The VFD120-E is available with 12 Vdc or 24 Vdc motor drives and is also designed to meet IP66. The two models have different electrical control arrangements, so their specifications should be checked individually.

A priority flow divider has three main hydraulic connections: inlet, priority and by-pass.

The inlet connection, normally identified as IN, P or PR, receives the flow from the hydraulic pump. The regulated or priority connection (REG) supplies the controlled flow to the hydraulic motor or other component.

The by-pass connection (BP) carries the remaining flow, which can return to the reservoir or supply another hydraulic circuit.

Webtec's VFD and RV, CK & M datasheets include hydraulic circuit diagrams showing typical arrangements for motor speed control, two functions operating from a single pump, and multiple motor circuits.

These diagrams should be used alongside the installation drawings to ensure the correct ports are connected for the intended application.

Reverse-flow capability depends on the valve model and its operating arrangement.

The Webtec CK Series includes an integral check valve between the priority and inlet connections specifically to allow reverse flow through the priority line.

The VFD120 also has reverse-flow capability, but this depends on the position of the control knob. The VFD190 allows intermittent reverse flow by pulling back the needle valve.

Reverse-flow operation should not be assumed to be available on every priority flow divider. The specific flow direction, control setting and operating requirements should be confirmed against the relevant datasheet or with Webtec's technical sales team.
 

The Webtec RV, CK & M Series provides three related variable priority flow divider arrangements, each suited to a different hydraulic circuit requirement.

The RV Series incorporates an adjustable relief valve between the priority and by-pass connections, providing pressure protection within the valve.

The CK Series incorporates a check valve between the priority and inlet connections to permit reverse flow through the priority line.

The M Series uses a compact manifold-mounted arrangement where installation space or hydraulic manifold integration is important.

All three use adjustable, pressure-compensated priority flow control, with the choice depending on the required hydraulic circuit function.

No. The integral relief valve fitted to the Webtec RV Series is intended to protect the flow divider against overpressure and must not be used as the main hydraulic system relief valve.

The RV relief valve is adjustable between 35 and 207 bar (508–3,000 psi) and is factory set to 138 bar (2,000 psi).

The RV relief-valve version also has a maximum priority flow of 50 L/min (13.2 US gpm), which is lower than the maximum flow capacity listed for the wider RV, CK & M family.

The main hydraulic circuit must therefore retain appropriate system pressure protection independently of the RV valve's integral relief function.

Yes. Anti-tamper options are available on selected Webtec manually adjustable priority flow dividers.

The VFD120 and VFD190 Series offer a locknut version that allows the priority flow setting to be secured, reducing the risk of unintended adjustment.

The RV, CK & M Series also offers an anti-tamper locknut option. The required regulated-flow setting should be specified when ordering this version.

These arrangements are useful where a hydraulic motor needs to operate at a predetermined flow rate and routine operator adjustment is not required.

Anti-tamper options should be checked against the specific model, as they are not listed as standard features across the entire VFD range.

Selecting a flow divider with suitable pressure-drop characteristics can help reduce energy losses in a hydraulic system.

Pressure loss across a flow control valve represents hydraulic energy that is not available to perform useful work.

Webtec's OptiFlo® technology combines adaptive pressure compensation with a design that helps minimise pressure losses while maintaining controlled priority flow.

The VFD120 and VFD190 Series, including the electrically operated VFD120-E and VFD120MD, have been designed to reduce pressure losses across the valve. This can help improve hydraulic system efficiency and reduce operating costs.

Their datasheets provide pressure-drop information at specified operating conditions, allowing engineers to assess the likely pressure loss for a selected flow size.

Webtec offers several porting and mounting options to suit different hydraulic installations.

The VFD50 is available with 3/8" BSPP or NPTF threaded connections, or a manifold-mounted arrangement.

The VFD120 Series offers BSPP, SAE, NPTF and metric port options, with availability depending on the model and flow size. The VFD190 is available with 1" BSPP or #16 SAE ORB connections.

The RV, CK & M Series offers BSPP, NPTF, SAE and metric connections, together with a dedicated manifold-mounted version.
Mounting hole positions, valve dimensions and connection details are provided in the individual datasheets. These should be checked before installation, particularly when replacing an existing valve or designing a compact hydraulic manifold.

The Webtec VFD50, VFD120, VFD120-E, VFD120MD, VFD190 and RV, CK & M Series specify a hydraulic fluid temperature range of -30 to 120 °C (-22 to 248 °F).

Their stated ambient operating temperature range is -30 to 50 °C (-22 to 122 °F).

The RV, CK & M datasheet specifically confirms compatibility with mineral hydraulic oils to ISO 11158, with other fluids requiring consultation with Webtec.

The VFD datasheets do not provide an equivalent explicit fluid compatibility specification. Suitability for particular hydraulic fluids, especially water-based, fire-resistant or other specialist media, should therefore be confirmed before selecting a valve.

The materials and operating conditions should always be considered together when determining fluid compatibility.

The maximum regulated flow depends on the available inlet flow, not just the selected valve's nominal priority-flow rating.

Webtec's VFD and RV, CK & M datasheets specify that the input flow affects the maximum priority flow that can be achieved. To reach the stated priority-flow capacity, the inlet flow must be greater than the required regulated flow.

The VFD range uses OptiFlo® technology to give preference to the priority circuit when inlet flow decreases, reducing the flow available to the by-pass circuit first. However, if the inlet flow is insufficient, the valve cannot maintain a regulated flow rate greater than the available supply.

When a hydraulic motor is running slower than expected, the available pump output, priority-flow setting and operating pressures should therefore be checked.