Hydraulic Valves

About Hydraulic Valves and Hydraulic Valve Manufacturers Including: Electric Hydraulic Valve, Hydraulic Ball Valves, Hydraulic Cartridge Valves, Hydraulic Check Valves, Hydraulic Control Valves, Hydraulic Directional Control Valves, Hydraulic Manifolds, Hydraulic Needle Valves, Hydraulic Proportional Valves, Hydraulic Relief Valve, Hydraulic Solenoid Valves & Hydraulics Valves.

Hydraulic valves are used to contain and transfer the flow and pressure of hydraulic fluid in hydraulic power systems. The specific types of valves range from those that have simple shutoff valves to precise control valves used in motion control systems. The basic components of a hydraulic valve are its body, bonnet, disc and seat. Other types of valves produced by hydraulic valve manufacturers have variations of these components, depending on their specific functions. Hydraulic valves are very similar to other valves in general purpose, regulating flow and design, but unlike many others, hydraulic valves are strictly used in hydraulic-related systems and components.
 
Hydraulic valves allow the flow of fluid when in their open position and prevent flow when closed. These valves work in tandem with hydraulic cylinders, pumps and motors directional control valves and relief valves. These valves are used for sealing and releasing in different situations, and some allow flow in only one direction while others are capable of managing more. Many hydraulic valves are computer controlled and do not require the monitoring of an operator.
 
Most valves made by hydraulic valve manufacturers are used within a fluid control system as a simple way to prevent improper levels of pressure and fluid from flowing. Some valves simply shut off flow when flow rates get too high. Other valves are designed to send impulses to valves further down the hydraulic line in order to provide a systematic balance of flow. Still other valves will direct the stream of the fluid to specific areas where fluid is needed, as do directional control valves. Directional control valves often have more than the standard two connections. Hydraulic tools and vehicles that use hydraulics commonly use these types of valves.
 
Hydraulic valve manufacturers produce hydraulic valves that vary greatly in size and shape. Narrowing of the fluid passage is a common method for reducing the overall size and cost of a valve. Sometimes a larger end is connected to a valve in order to make the valve capable of connecting to a larger line. Some valves use electro-magnetic power to actuate the valve. Current is applied to a coil within the valve and a magnetic field is created. These types of valves are used as a manual switch or control within a hydraulic system.

Hydraulic Valves Image Provided by Fulflo Specialties, Inc.

Types of Hydraulic Valves

• Ball valves are quarter turn, straight through hydraulic valves that have a round end with matching rounded seats to permit uniform sealing pressure. Ball valves are used in situations when tight shut-off is necessary.
  
• Cartridge valves are completely bodiless and can be removed and replaced easily without dismantling.
• Check valves are hydraulic valves which allow flow in only one direction. Any backflow forces the valve to shut.
  
• Directional control valves control the direction of the hydraulic fluid to the point where it is needed. Directional control valves are useful for hydraulic tools and farm equipment that use hydraulics.
  
• Float valves are valves that automatically open or close as the liquid level changes. Float valves are operated mechanically by a float that rests on top of the liquid.
  
• Gate valves are linear motion valves in which a flat closure element slides into the flow stream to provide shut-off. Gate valves are designed to minimize pressure drop in fully open positions.
  
• Globe valves are multi-turn valves that have a closing element that moves perpendicular to the valve body seat and generally seals in a plane parallel to the direction of flow. This type of valve is suited both for throttling and general flow control.
• Relief valves are made to release pressure. When safe pressure levels are exceeded, the valve opens and then closes when levels are back to safe presets.
• Solenoid valves are made from wire coil and a movable plunger that is set against the coil. Solenoid valves are electromechanical devices that use solenoid to control the valve's actuation.

Hydraulic Valve Terms

Accumulator - A container that stores fluid under pressure and is used to absorb hydraulic shock.
 
Back Pressure - The pressure exerted on the downstream side of a valve seat.
 
Bonnet - A removable outer piece of a valve that makes assembly possible, sometimes considered part of the body.
 
Bleed - A small controlled line of fluid from a pressurized system.
 
Cavitation - When gas enters into the liquid stream and causes the pressure to reduce to the vapor pressure.
 
Cylinder - A device that is used to convert hydraulic energy to mechanical motion and force.
 
Differential Set Pressure - The pressure differential between the set pressure and constant superimposed backpressure.
 
Disc - The o-ring or metal wedge that seals the valve to the seat.
 
Full Flow - A condition in which the maximum amount of fluid must be allowed to travel through the system.
 
Flow Rate - The volume, mass or weight of fluid passing through a flow passage, regulated by valves.
 
Gear Boxes - Used to ensure easier operation of larger valves, particularly ball valves.
 
Hydraulic Actuator - A device fitted to the valve stem that uses hydraulic energy to open and close the valve.
 
Hydraulics - The study of fluids in motion.
 
Meter - Used to measure pressure level and volume of fluid in a hydraulic system.
 
Overpressure - The pressure increase or accumulation above the set pressure when the valve is discharging flow.
 
Pre-Charge - The residual pressure in a hydraulic actuator before the introduction of oil.
 
Reduced Bore - Indicates that the internal diameter of the valve is lower than the piping to which the valve is fitted.
 
Seal - A device that restricts the escape of fluid or entrance of foreign material.
 
Seat - The fixed surface on which a valve rests or against which it presses.
 
Solenoid - A coil of wire designed to carry an electrical current producing a magnetic field.
 
Superimposed Backpressure - The static pressure existing at the outlet of the relief device at the time the device is required to operate. It is a result of the pressure in the discharge system coming from another source. May be constant or variable.
 
Static Water Pressure - The measured pressure of water when it is not moving.
 
Viscosity - A measure of the internal friction or resistance of a fluid to flow. Viscosity is determined by measuring the liquid shear strength under specific conditions.