The Criteria for Selecting a Suitable Hydraulic Valve

No matter the scale, complexity or application of a hydraulic system, the correct selection of a hydraulic control valve is crucial to ensuring performance, reliability and longevity.

Hydraulic valves play an important role in controlling the direction of fluid through a circuit. By ensuring a regulated flow, valves can control the speed of motors and the movement of cylinders, therefore ensuring that the system is operating efficiently and at the specified performance.

There are many different types of hydraulic valves available, which can make selecting the right one somewhat of a challenge, particularly when designing a new hydraulic system. When it comes to replacing a valve, a like-for-like replacement should be sourced.

In all other cases, our selection guide is here to help.

Hydraulic valve selection guide

In order to select the most suitable hydraulic valve for your application, you must have a good understanding of your system requirements and the options available to you.

Below, we will highlight some of the key factors that should be taken into account.

Media characteristics

The characteristics of the hydraulic fluid to be used in the system plays a vital role in determining which components are best suited – and this is no different when it comes to hydraulic valves.

Hydraulic fluids vary in viscosity and corrosiveness. With that in mind, the valve material must be compatible with the liquid to avoid any performance issues. Materials such as cast iron, brass and aluminium may potentially be affected by certain fluids.

As a brief guide, steel or metal valves should be used for pressurised fluids, and PTFE or PFA should be implemented where highly corrosive or harsh fluids are used.

Operating conditions

Whilst hydraulic valves are typically robust and designed to withstand harsh operating conditions, some materials naturally perform better than others in specific applications.

The pressure, flow rate and temperature of the system should be kept in mind when selecting a valve. For high temperature and pressure applications, steel or metal valves are the most suitable in comparison to plastic or lower grade materials.

Pressure – The working pressure of the valve should be equal to or greater than the maximum system pressure.

Temperature – The fluid temperature should be maintained at a level that is specified to be compatible with the valve.

Size

The valve should be sized correctly with the appropriate fittings or mounting connections to avoid any common issues such as pressure loss or damage due to excessive heat generation caused by too high a fluid velocity.

A valve that is too small may not have the capacity to pass the required flow, and one that is too large can lead to undesirable changes in fluid flow.

As a general rule of thumb, hydraulic valves should be sized to operate between 60-80% open at the maximum required flow rate.

Valve function

It’s important to consider the function that your valve will be required to perform. If it’s for a simple on/off control, a 2-way valve may be adequate. Whereas, if you also need the function of mixing or diverting the fluid, opt for a 3-way valve.

Similarly, if it’s likely that your valve will be open more often than it is closed, select one that is designed to sit in that position for the most part, and vice versa.

Valve operation

Different valves are designed to be operated in different ways – i.e. manually hand-operated or automatic. Depending on the requirements of your system, one of these will make a better selection than the other.

Selecting the right hydraulic valve

It’s all too common that oversized or incompatible valves are implemented in a system, which has a huge impact on operational efficiency and accuracy. Sizing and selecting the right hydraulic valve requires in-depth knowledge of hydraulic equipment and best practices.

In these situations, it’s always best to seek the help of an expert. Primary Fluid Power are one of the leading UK distributors of hydraulic components and accessories and can supply an extensive range of hydraulic valves from leading manufacturers including Roquet and Eaton Vickers.

Our experienced engineers are on hand to recommend the most suitable product for you, with the in-house capabilities of building or modifying existing products to meet your exact specifications.