Types of Hydraulic Valves: A Pocket Guide

2024-03-18

When you inspect the components of hydraulic equipment/machinery, you can find one or more hydraulic valves in that. In the market, you can find different types of hydraulic valves developed by different manufacturers. These valves will perform various functions depending on the job assigned. Some hydraulic equipment requires an individual valve, whereas others use a combination of valves to operate.

Hydraulic seals

Now let’s begin with hydraulic valve basics. A hydraulic valve is a mechanical device used for controlling the flow of liquid or gas through it. Hydraulic valves control the flow by opening and closing the device. Also, these valves are manufactured using tough materials(steel or iron) for withstanding high fluid pressure of more than 3000 psi.

To actuate a hydraulic valve, we have many methods. They can be mechanically operated using a handle, knob, or cam, solenoid-operated, or pilot-operated. On/Off valves, and continuous regulating valves are the two classifications based on the working. Modular mounting, screw-in cartridge type, modular sandwich type, threaded connection, slip-in cartridge type, etc. are the different valve installation mountings.

Based on the functions, hydraulic valves are classified into a directional control valve, a hydraulic pressure control valve, and a hydraulic flow control valve.

1. Directional Control Valve

As the name suggests, the directional control valves are used to direct the flow of fluid through the system. These valves can pause and restart the movement of fluids. Also, they can change the direction of fluid flow. Check valves, prefill valves, spool valves, etc. are the various directional control valves used to ensure proper flow of fluids within the system. The check valves and prefill valves are non-return valves. Check valves block bidirectional fluid flow and control the pressure. Whereas, the prefill valve passes the fluid through the hydraulic cylinder and tank. Spool valves control the fluid flow within the system.

The 2-way directional control valve is the simplest directional control valve that has two ports called inlet and outlet. These valves are used in water faucets and they can start or stop the fluid flow. A 3-way directional control valve has 3 working ports called inlet, outlet, and exhaust. They are used in single-acting cylinders and the third working port can block the flow of all ports. Similarly, there are 4-way valves and 5-way valves used in double-acting actuators and air circuits respectively.

2. Hydraulic Pressure Control Valve

The hydraulic pressure control valve plays a vital role in controlling the leakages and bursting of pipes. Pressure control valves regulate the pressure of the fluid passing through the pipe by releasing the excess pressure. These valves maintain the pressure as entered manually by the operator.

Hydraulic pressure relief valves, sequence valves, counter-balance valves, and pressure-reducing valves are the different types. The counter-balance valve creates dynamic control within the system and the sequence valve detects the extreme pressure. The pressure relief valve is one of the important types that set the pressure limit by transferring excess back to the tank.

3. Hydraulic Flow Control Valve

The flow control valves are used for controlling and adjusting the fluid or gas flow through the system. These valves can optimize the hydraulic system performance. Flow control valves will monitor and regulate pressure fluctuations in the system. It prevents the flow towards ill-founded system components.

The throttle valve, speed control valve, manifold set flow valve, etc. are the types of flow control valves. Another type of flow control valve is a flow divider. This valve takes fluid input from one source and redirects this fluid to two or more sources.

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