4 types of hydraulic valves and their working principles

There are many types of Hydraulic Valves available in the industry. Hydraulic Valves are mechanical equipment for controlling the flow of fluid in hydraulic pipes or systems. They can be utilized to thoroughly check the flow level to a specific domain, redirect pressurized fluid or close a line.

Hydraulic valves are available in various characteristics similar to other valves, such as bypass, needle, regulating, relief, ball, butterfly, pilot-operated, check, diverter, Proportional Valve, and Directional Valves. In general, these hydraulic valves may be described as being of three main varieties which are:

1) Hydraulic Flow Control Valves
2) Hydraulic Pressure Control Valve
3) Hydraulic Directional Control Valve

Types of Hydraulic Valves

Hydraulic Flow Control Valves

Hydraulic flow control valves are used to regulate the flow volume of passing fluid in hydraulic systems. These types of valves have a movable gate that changes the flow domain to modify the flow rate in the valve. For example, this type of hydraulic valve would be used in control circuits for devices, such as actuators, cylinders, or motors. The speed of these devices is a function of flow rate linearly, i.e. decreasing the flow rate reduces their driving speed and vice versa.

The different types of hydraulic flow control valves are movable flow control valves, pressure compensated flow control valves, fixed flow control valves, and throttling flow control valves. The method of flow control in these valves are modifying based on the mechanical shape of the valve, which regularly is one of the well-known styles same as other valves, namely: Ball.Butterfly.Diaphragm.Needle.Plug.

Some of the conventional hydraulic flow control valves are:

· Pressure-compensated proportional flow-control valves
· Deceleration valves
· Proportional flow-control logic valves
· Pressure- and temperature-compensated, variable flow valves
· Pressure-compensated, variable flow valves
· Priority valves

Hydraulic Pressure Control Valves
Hydraulic pressure control valves are used to regulate the fluid pressure passing through hydraulic arrangements to keep that pressure at desired amount as restricted by the System operator. Fluid systems are typically produced for operation at a fixed range of pressures. These valves serve a crucial role in preventing rises in pressure that may result in hydraulic fluid leaks or the bursting of pipes and tubes. They are also installed to have the desired pressure in some sections of a hydraulic circuit.

Several kinds of pressure control valves are widespread in hydraulic systems, including reducing valves, relief valves, sequence valves, counterbalance valves, and unloading valves.

Hydraulic Directional Control Valves

We use hydraulic directional control valves to track fluid in a system or circuit to several devices as demanded. They shift between discrete positions such as extend, retract, or neutral locations for controlling a hydraulic cylinder. They can also change into intermediate states to control an actuator`s acceleration, speed or direction.

Discrete hydraulic Directional control valves are a simple form of binary valves, passing blocking the fluid flow. If fluid tries to pass in the reverse direction, a check valve seals the system using a ball, plunger or poppet.

Hydraulic directional control valves with more complicated characteristics may have multiple gates, as their characteristics allow them to switch fluid within distinct ports depending on the device they supply with hydraulic fluid. Consequently, they are discriminated against by standardized numbering systems that have two values, the same as 4/3 or 2/2. The first number indicates the number of valve ports, and the second number indicates the number of valve positions that the device can achieve.

Here we list some of the classes for directional-control valves. You can identify these valves according to the:

· The number of flow ways in the extreme positions.

· The number of spool positions.
· Method of providing spool return.
· Method of shifting a spool.
· Flow pattern in the crossover or center position.

The function of the Hydraulic Control Valve

Several hydraulic directional control valves have spools. Spools slide between parts allowing liquid to flow in open gates, based on the state of the spool in the body. Valves may have one or multiple spools to achieve the designed port control. Other flow control elements in these valves may be poppets or plungers.

The valve part that drives these flow control components is known as the actuator or operator of the valve. These hydraulic valves can present proper timing or sequencing of the valve position modifications needing to control the hydraulic systems or circuits. There are many possibilities for the actuator mechanism, including pilot, electrical/electronic, mechanical actuation.