Familiarizing yourself with the various components that make up the hydraulic systems used by your manufacturing plant can help you make informed decisions regarding the priority of upgrades based on what may be most efficient and effective. The flow control of hydraulic systems is to regulate speed, which affects the capability and energy efficiency of the entire system. Although fluid control is mainly regulated by the viscosity of the fluid, which should ideally be at 25 to 36 centistokes, the types of flow-control valves installed will also make a huge difference. This article will provide you with an overview of one of the more popular and advanced types: proportional flow control valves.

The Fundamentals of Proportional Flow-Control Valves

Proportional flow-control valves involve some of the most advanced technology for fluid control, as they couple and integrate state-of-the-art hydraulic valve actuation with electronic control. As a result, the accuracy and efficiency of the entire system is increased while the number of components that are required decreases. Proportional flow-control valves rely on three main components: 

  • a proportional solenoid or a pilot.
  • a metering area. This is where the valve spool will be installed.
  • a linear variable differential transformer (LVDT) or any other type of electronic position-feedback device.

Due to the complexity of flow-control valves, a programmable logic controller (PLC) will also be required for control. The PLC is the controlling device that monitors the operation of the hydraulic system and sends out signals to the proportional flow-control valves to adjust and modify its performance.

Changes and Adjustments Made to the Signal Pathway

Once a change in the system output or requirements have been detected by the PLC, analog electrical signal will be sent to the pilot or proportional solenoid of the flow-control valves. This induces an electromechanical force at the valve spool that will open up a flow path for the fluid. The flow can be controlled by the magnitude of the electrical signal that is sent. All shifts in movements induced by the valve spool will be monitored by the LVDT, which is responsible for feeding back the information to the PLC. 

The entire cycle then repeats itself. As the proportional flow-control valves are connected to a PLC, the entire process is automated once it has been set up. This reduces the need for manual calculations regarding which flow rate may be most efficient, especially with a system that may be facing constantly changing inputs. You will save a lot of time, and the hydraulic system will respond immediately to reduce waste and inefficiencies. 

Ideal Locations for the Installation of Proportional Flow-Control Valves 

The most important role of a proportional flow-control valve is its ability to make sure that all of the variables are proportionate to one another. All input current changes will change the position of the valve spool, the size of the flow path and the actuator speed. This controls the fluid flow rate. Proportional flow-control valves are most ideal in applications that require very precise control, whether it involves system acceleration or deceleration.

Proportional flow-control valves are also ideal in situations when the temperature of the fluid within the hydraulic system is subject to constant changes.


Many people who own manufacturing plants may be hesitant to upgrade the rudimentary fluid-control valves, like orifices, in their hydraulic system to proportional flow-control valves due to the installation costs that are involved. Although the initial installation costs can be quite high, you will see an increase in overall accuracy and efficiency, which will help you reduce waste and expenses. In short, you will be saving money in the long run. Speak with a fluid control products supplier to determine whether proportional flow-control valves are most ideal for your situation.