Hydraulic valves are automatic devices that are utilized to control the flow of liquid in a hydraulic circuit or system. They can be used to completely close a line, to redirect pressurized fluid, or to control flow to a specific area. Intended in a broad variety of styles, these valves can be physically or automatically work by physical, automatic, pneumatic, hydraulic, or electrical activation.
Hydraulic valves must be able to withstand high fluid pressures as the nature of many hydraulic systems requires high pressures of up to 3000 psi or more. For this reason, they are often made from steel, cast iron, or other metals that are strong enough to withstand continuous operation under high pressure conditions. This article will provide information on hydraulic valves, including the different types, their designs and related characteristics.
Types of hydraulic valves
Hydraulic valves are available in a wide variety of styles, including many common to other valve types such as ball, butterfly, bypass, check, needle, and changeover, and control, pilot operated, proportional and directional. Broadly speaking, these hydraulic valves can be characterized as three main types:
- Hydraulic pressure control valves
- Hydraulic flow control valves
- Hydraulic directional valve
Hydraulic pressure control valves
Hydraulic pressure control valves are used to regulate the pressure of fluid flowing through hydraulic systems to maintain that pressure at a desired level, as determined by the system operator. Fluid systems are typically designed to operate within a given pressure range. These types of valves play a key role in preventing pressure build-up, which can lead to hydraulic fluid leaks or rupture of pipes and tubing. They are also used to maintain a given pressure in a part of the hydraulic circuit.
The various types of pressure control valves used in hydraulic systems include relief valves, pressure relief valves, sequence valves, balance valves, and relief valves.
Hydraulic flow control valves
Hydraulic flow control valves are used to adjust the flow of hydraulic fluid in a hydraulic system. These valves have a port that can be adjusted so that the flow area can be changed to accommodate a change in the flow rate through the valve. An example of how this type of hydraulic valve can be used is a control circuit for devices such as cylinders, motors, or actuators. The speed of movement of these devices directly depends on the flow rate – a decrease in the flow rate reduces the speed of their operation and vice versa. A variety of types of hydraulic control valves contain fixed control valves, adaptable control valves, flow control throttling valves, and force compensated control valves.
Hydraulic directional control valves
Hydraulic directional control valves are used to direct hydraulic fluid in a circuit or system to various devices as needed. They switch between discrete positions such as extend, retract or neutral, for example to control a hydraulic cylinder. They can also transition to intermediate states in which they can be used to control the speed, direction, or acceleration of the drive. The simple form of the Discrete Hydraulic Control Valve is a binary valve that either blocks or allows fluid flow. Make sure valves are an instance and use a needle, ball, or poppet to close in opposition to the seat when fluid tries to flow in the reverse direction of flow.
Hydraulic Valve Specifications
Hydraulic valves are particular using more than a few limitations that narrate to their dimension, ability, connections and actuation device. Typical specifications for these valves are outlined below, but it should be noted that these parameters can vary from manufacturer to supplier of valves, so there may be differences in presentation from supplier to supplier.