Choosing Hydraulic Valves
There are five main types of hydraulic valves that that Yuken Europe offer, all of which are Comité Européen des Transmissions Oléohydrauliques et Pneumatiques (CETOP) compliant. Hydraulic valves that are recognised by CETOP, the European fluid power committee, are interchangeable within most types of hydraulic equipment.
Valves in hydraulic equipment systems regulate and control the flow of hydraulic fluid but in certain applications, there are different requirements for fluid flow so it is important that the correct valve is used for the correct purpose.
Flow control valves are designed to regulate fluid flow in two directions and to allow for fine tuning of the flow rate are variable. The valves control the travel of fluid in one direction however, in reverse the flow is free and can’t be controlled in the same way as when forward flowing. A pilot-operated check valve is thus used to regulate the flow of hydraulic fluid to a cylinder and when necessary, preventing unwanted cylinder movement. A pressure relief valve can be used in combination with a solenoid valve or a pilot operated check valve, to release the pressure held up by a pilot operated check valve, or to limit pressure in a control line, to a solenoid valve. Yuken Europe’s solenoid valves have a four-landed control spool whose purpose is to alter fluid flow direction. They are all rated to ISO4401-03-02-0-94 and DIN 240 340-A6 and can manage pressures up to 320 bar and a flow rate of up to 60L per minute. With a world-wide distribution network Yuken Europe’s hydraulic valves can be delivered anywhere, quickly.
Solenoid valves are sometimes opted-for over flow control valves due to their ability to regulate directional flow, as opposed to a single direction. Flow control valves are appropriate for applications where movement of a cylinder in one direction has to be regulated carefully but when it returns to its original position, no control is needed over either flow or speed of movement. These can be fitted in any direction, leaving it up to the user to decide which direction requires controlling. For appliances where control in both directions is needed over the flow rate e.g. in technologies that control gates or doors at a set speed, a solenoid valve would be a better choice, as it allows for finer control of movement and speed in opposing directions.
When a hydraulic valve needs to be replaced it is usual to replace it with a valve of the same type, buying from Yuken Europe ensures you get a valve that is perfect as a replacement regardless of whether your equipment was made by a different manufacturer. At times a hydraulic valve will need to be replaced with a different type of valve, for example, when machine specifications or usage changes, such as a piece of machinery that previously used a flow control valve, needs operational advantages to have better control over the hydraulic flow in two directions.
Choosing the right type of valve is relatively easy when simply replacing a valve but when designing new hydraulic machinery, these decisions are a little more difficult. Knowledge and understanding of the function the system is needed to perform is elemental but going a deeper into the additional functionalities is often necessary for performance improvements that could be made with a different type of valve choice, can help inform design choices at the outset, resulting in machinery that is more user friendly, provide a greater return on investment, and lower ongoing costs.
