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A hydraulic seal is a relatively soft, non-metallic ring, captured in a groove or fixed in a combination of rings, forming a seal assembly, to block or separate fluid in reciprocating motion applications. Hydraulic seals are vital in machinery. Their use is critical in providing a way for fluid power to be converted to linear motion.
Hydraulic seals can be made from a variety of materials such as polyurethane, rubber or PTFE. [1] The type of material is determined by the specific operating conditions or limits due to fluid type, pressure, fluid chemical compatibility or temperature.
A static hydraulic seal is located in a groove and sees no movement - only sealing within its confined space, acting like a gasket. To achieve this the gasket should be under pressure. The pressure is applied by tightening of the bolts.
A type of dynamic hydraulic seal called a rod seal is exposed to movement on its inner diameter along the shaft or rod of a hydraulic cylinder. Hydraulic Piston seals prevent fluid from crossing the area of the piston head. Rod seals ensure that fluid does not leak from the cylinder and adequate pressure is maintained. Wiper seals are installed to prevent contamination from entering the hydraulic system. [2] A rod seal prevents leakage of hydraulic fluid to the outside of the sealing system. Additionally, rod seals help contribute, in combination with a wiper seal, to preventing contamination of the environment. [3] A type of dynamic hydraulic seal called a piston seal is exposed to movement on its outer diameter along the tube or bore of a hydraulic cylinder. Different Piston Seal profiles offer distinct advantages depending on the sealing application. Temperature, Pressure, Stroke Speed and other environmental considerations would lead users to different profiles and materials. [4]
A pump is a device that moves fluids, or sometimes slurries, by mechanical action, typically converted from electrical energy into hydraulic energy. Pumps can be classified into three major groups according to the method they use to move the fluid: direct lift, displacement, and gravity pumps.
A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the fluid in the cylinder. In some engines, the piston also acts as a valve by covering and uncovering ports in the cylinder.
A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert pressure into a rotating motion. This article describes the common features of all types. The main types are: the internal combustion engine, used extensively in motor vehicles; the steam engine, the mainstay of the Industrial Revolution; and the Stirling engine for niche applications. Internal combustion engines are further classified in two ways: either a spark-ignition (SI) engine, where the spark plug initiates the combustion; or a compression-ignition (CI) engine, where the air within the cylinder is compressed, thus heating it, so that the heated air ignites fuel that is injected then or earlier.
An end-face mechanical seal, or a mechanical end-face seal, also referred to as a mechanical face seal but usually simply as a mechanical seal, is a type of seal used in rotating equipment, such as pumps, mixers, blowers, and compressors. When a pump operates, the liquid could leak out of the pump between the rotating shaft and the stationary pump casing. Since the shaft rotates, preventing this leakage can be difficult. Earlier pump models used mechanical packing to seal the shaft. Since World War II, mechanical seals have replaced packing in many applications.
A diaphragm pump is a positive displacement pump that uses a combination of the reciprocating action of a rubber, thermoplastic or teflon diaphragm and suitable valves on either side of the diaphragm (check valve, butterfly valves, flap valves, or any other form of shut-off valves) to pump a fluid.
A gasket is a mechanical seal which fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression. Given the potential cost and safety implications of faulty or leaking gaskets, it is critical that the correct gasket material is selected to fit the needs of the application.
An O-ring, also known as a packing or a toric joint, is a mechanical gasket in the shape of a torus; it is a loop of elastomer with a round cross-section, designed to be seated in a groove and compressed during assembly between two or more parts, creating a seal at the interface.
A mechanical seal is a device that helps join systems or mechanisms together by preventing leakage, containing pressure, or excluding contamination. The effectiveness of a seal is dependent on adhesion in the case of sealants and compression in the case of gaskets. The seals are installed in pumps in a wide range of industries including chemicals, water supply, paper production, food processing and many other applications.
Hydraulic machines use liquid fluid power to perform work. Heavy construction vehicles are a common example. In this type of machine, hydraulic fluid is pumped to various hydraulic motors and hydraulic cylinders throughout the machine and becomes pressurized according to the resistance present. The fluid is controlled directly or automatically by control valves and distributed through hoses, tubes, or pipes.
A hydraulic brake is an arrangement of braking mechanism which uses brake fluid, typically containing glycol ethers or diethylene glycol, to transfer pressure from the controlling mechanism to the braking mechanism.
A hydraulic cylinder is a mechanical actuator that is used to give a unidirectional force through a unidirectional stroke. It has many applications, notably in construction equipment, manufacturing machinery, and civil engineering.
Pneumatic cylinder(s) are mechanical devices which use the power of compressed gas to produce a force in a reciprocating linear motion.
An axial piston pump is a positive displacement pump that has a number of pistons in a circular array within a cylinder block. It can be used as a stand-alone pump, a hydraulic motor or an automotive air conditioning compressor.
A fitting or adapter is used in pipe systems to connect straight sections of pipe or tube, adapt to different sizes or shapes, and for other purposes such as regulating fluid flow. These fittings are used in plumbing to manipulate the conveyance of water, gas, or liquid waste in domestic or commercial environments, within a system of pipes or tubes.
Artificial lift refers to the use of artificial means to increase the flow of liquids, such as crude oil or water, from a production well. Generally this is achieved by the use of a mechanical device inside the well or by decreasing the weight of the hydrostatic column by injecting gas into the liquid some distance down the well. A newer method called Continuous Belt Transportation (CBT) uses an oil absorbing belt to extract from marginal and idle wells. Artificial lift is needed in wells when there is insufficient pressure in the reservoir to lift the produced fluids to the surface, but often used in naturally flowing wells to increase the flow rate above what would flow naturally. The produced fluid can be oil, water or a mix of oil and water, typically mixed with some amount of gas.
A plunger pump is a type of positive displacement pump where the high-pressure seal is stationary and a smooth cylindrical plunger slides through the seal. This makes them different from piston pumps and allows them to be used at higher pressures. This type of pump is often used to transfer municipal and industrial sewage.
High-density solids pumps are hydrostatically operating machines which displace the medium being pumped and thus create a flow.
Reciprocating engine cylinders are often classified by whether they are single- or double-acting, depending on how the working fluid acts on the piston.
A Wills Ring or Cooper Ring is a form of all-metallic O-ring seal. They are used for extremely arduous service, such as sealing the head gasket of high performance piston engines.