Fluid Power Valve Basics: How To Pick the Correct Valve

 In AHE News

A hydraulic power unit utilizes the conjunction of its complex components in order to transfer energy through a fluid. When broken down further each of those crucial components contains even more pertinent pieces.

The basic fluid power unit is composed of major products such as pumps and controllers, filters and tubing, and cylinders and valves. The fluid power valve is housed inside the chamber walls of the system’s cylinder and implementing the correct valve is critical in the productivity and operation of your unit. More commonly, valves are remote mounted or modular stacked, in conjunction with a valve manifold or subbase.

The Basic Role of a Hydraulic Valve

Simply put, the role of the valve within a hydraulic power unit is to regulate the flow and pressure level of the fluid operating in the systems. Digressing deeper there are numerous varieties of hydraulic valves each holding a particular specialty or application. As mentioned the valve can be found inside of the walls or passageways of the machine’s cylinder(s) and work with other components like a piston ring and valve spring to direct the fluid’s flow. Same as above, this is a rare case. Because the fluidity of the oil or water is the backbone of the unit’s functionality it’s important to integrate the correct valves.

Browse Our Various Hydraulic Valves


Types of Valves

Various valves play different roles within the hydraulic power unit and when utilized correctly can improve the overall flow of your system. Valves can be classified as a key player in the operation of the system and therefore need to be strategically placed and utilized. The hydraulic valves can be categorized into three main areas and from there more specified types of valves.

Flow Control Hydraulic Valves

You can predict by the name the key role of these particular hydraulic valves. The multiple types of flow control valves constantly monitor and regulate the rate of the unit’s fluid flow. By reacting to the fluctuations of pressure in the circuit it’s able to maintain the correct flow rate, therefore, sustaining smooth production. For example, if and when the pressure within the system reaches a certain threshold the valve will react by shutting or opening to maintain the correct flow. Major flow-control valves include:

Needle Valves:
This highly adaptable, simple valve is made in a variety of shapes and sizes allowing use with or without a check valve. This adjustable option determines the flow rate through not only pressure of the fluid, but also the temperature.

Pressure-Compensated Flow Control Valves:
When working with a fluid power unit that can withstand a vast range of actuator speeds stemming from pressure changes caused by load variations, you need a pressure compensated flow control valve.

Temperature-Compensated Flow Control Valves:
With the use of its orifices, these valves alter flow rates in order to combat any viscosity or temperature change within the unit’s oil.

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Pressure Valves

With flow control valves maintaining the fluid’s journey throughout the unit, the pressure valve works to regulate the levels of pressure. Each hydraulic unit contains an ideal pressure level depending on coinciding factors such as use, size, etc. By determining this pressure and integrating various pressure valves you can ensure a fluid, efficient system. Installing the right pressure valves will help regulate the fluid’s pressure and each valve uses a unique tactic to do so.

Relief Valves:
Every hydraulic unit is required to have a relief valve or multiple. Not necessarily required, but use is encouraged. In conjunction with a positive displacement pump, this hydraulic valve protects again excessive pressure. Connecting to the pump outlet and tank the valve is often closed until pressure relief is a need in which then the valve will open according to the need of relief.

Sequence Valves:
This valve uses two branches of a circuit in order to control the order of operation. Based off of the indicated pressure signals the sequence valve will regulate the operating order. The branch with the primary port of the valve is the home of the system’s fluid until the specified pressure level is reached. At that point, the valve will direct the fluid to its secondary branch.

Unloading Valves:
If your system is using a two-volume circuit, then this is the most common valve used. The two circuit requirements when incorporating an unloading valve includes a large quantity of fluid at low pressure for one part of the circuit, and its counterpart should be a low amount of fluid with a high-pressure level.

Pressure-Reducing Valves:
This adjustable valve is commonly used and can provide relief to a range of circuits and levels. In order to regulate the normal pressure level in the main circuit, the pressure-reducing valve will reduce pressure to a lower requirement for a branch circuit. By partially closing when the pressure level is reached in the branch circuit, the valve is able to allow just enough fluid through the system to adhere to the required pressure.

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Directional Valves

There are three main roles of directional valves:

  • Direct fluid in a specified direction in a hydraulic system
  • Cease or initiate the flow of fluid in power unit
  • Change direction of fluid within a circuit

In a single hydraulic power unit, there are often a variety of directional valves integrated. This allows direct control over the fluid’s flow direction throughout the system’s operation. You should always plan out the use of your units through fluid power drawings to ensure the proper flow of the fluid, which in turn allows you to pick the correct valve.

(The Nachi SS Series Directional Valve is a Top-Seller!)

Check Valves:
The check valve is a multi-use valve allowing control over direction and pressure. With a simple make-up of a ball, seat and sometimes a spring placed between two ports, the check valve is a basic yet extremely essential component for your hydraulic power system.

Counterbalance Valves:
When your system is dealing with the need for an adjustable resistance against the flow in one direction, however, allow free flowing fluid in the opposite direction, you will need to use a counterbalance valve. This valve will help avoid uncontrolled movement of the system, as well as, has the ability to support weight in a specified circuit while fluid flows to the other working parts throughout the rest of the power unit.

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Air & Hydraulics Equipment Can Help With All of Your Pneumatic and Hydraulic Components

Whether it’s searching for the ideal fluid power valve, assessing a filtration system or repairing a hydraulic power unit, our team of experts has you covered! We have five locations throughout Middle Tennessee in addition to our fully-stocked online shop, so you are sure to find what you’re looking for. Contact us today for all of your air & hydraulic equipment needs!

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