Hydraulics
(149)Hydraulic systems
Hydraulic systems, together with appropriate electronic control systems, are an important part of mechatronic systems and are indispensable when high force and high torque are required. In our catalogue, you can select the required accessories in the category of hydraulics and necessary sensors. Main features of hydraulic systems:
- small components can transmit considerable forces,
- speed changes of the actuators are fast and stepless,
- protection is provided by pressure limiting valves,
- viscosity of hydraulic oils depends on the temperature,
- leaks cause power loss,
- occurrence of vibrations and noise.
Pressure and related concepts
Units of pressure
Pressure is sometimes expressed in different units, i.e. the most common SI units – pascals (Pa) and derived megapascals (MPa), where 1 Pa = 1 N/m2, and bars (bar), which are equal to 100 000 Pa or 0.1 MPa.
Pressure – an important factor when choosing products
The maximum pressure is one of the important parameters when choosing components for a hydraulic system to ensure safe and trouble-free operation of the equipment. This applies to connectors, but also to valves or other components of the system.
Tightness of hydraulic systems
Hydraulic systems, while being relatively light, make it possible to achieve high force and torque. They allow for much more smooth movement compared to electric or pneumatic drives. Among the main drawbacks of hydraulic systems are the need to maintain tightness of the installation connections and their vulnerability to pressure fluid contamination.
Sealing material
As already mentioned, leaks pose a serious threat to the efficiency of hydraulic systems. For this reason, the choice of components in terms of the right sealing material can be crucial. The sealing materials available in our catalogue include: EPDM, FKM, NBR and PTFE. Each of these has its specific characteristics, and it is easy to choose one that will make our hydraulic accessories the perfect fit for our installation.
EPDM
The term EPDM refers to a material that is a combination of ethylene, propylene and monomer. It is commonly referred to as synthetic rubber. Due to proper preparation and a good chemical composition, it is characterised by impressive sealing properties. It is extremely flexible and exhibits high tensile strength. It provides an alternative to natural rubber extracted from various species of trees. In industrial terms, it is referred to as EPDM.
FKM
FKM is an abbreviation for a fluorine chemical compound, also known as FPM. To distinguish between the terms, it is worth knowing that FKM is the international ISO designation for all fluoroelastomers, while FPM is the German DIN designation. The term FKM covers a variety of synthetic polymer blends, all of which contain a VDF (vinylidene difluoride) monomer. They exhibit good heat and ozone resistance, as well as resistance to a wide range of chemicals, which makes FKM a truly universal elastomer.
NBR
NBR rubber is a rubber compound that is distinguished by its increased resistance to oils, fuels and fats as its ACN content increases. However, with an increase in the ACN content, its resistance to low temperatures decreases. An ozone-resistant compound can be obtained by adding PVC to NBR in the manufacturing process, whereas enriching NBR with a phenolic resin produces rubber that is flexible when stretched and resistant to hot water.
The ‘N’ in NBR stands for nitrile, which is one of the most popular types of rubber. Depending on its composition, NBR can be resistant to engine oils, heating oils, transformer oils, lubricants, hydraulic fluids and many other chemicals. It is also resistant to alcohol, salt solutions, dilute acids and bases. However, it is not resistant to oils and greases containing silicone, glycol-based brake fluids and HFD hydraulic fluids. It is also not resistant to concentrated acids, lyes, aromatic and chlorinated hydrocarbons, and esters.
PTFE
Polytetrafluoroethylene (PTFE), also known as polytetrafluoroethene, is a linearly structured, unbranched polymer containing fluorine and carbon, and it is partially crystalline. It is known by the trade name Teflon™, reserved by the DuPont company. Other trade names for PTFE include Dyneon PTFE (formerly Hostaflon) and Gore-Tex for PTFE membranes.
Testing the quality of a hydraulic system by performing a leak test
The smooth operation of a hydraulic system depends, to a large extent, on the tightness of its individual components, which can be achieved through proper connections, as well as the quality of the system elements. Hydraulic accessories, thanks to their good quality, definitely influence the tightness of the entire system, too. Lack of tightness can be disastrous due to high pressure inside the installation. A thorough leak test is therefore of great importance for the proper functioning of the entire system. A leak test can be carried out using various methods. Among the most precise and relatively inexpensive methods are the vacuum method and the overpressure method, using a gas spectrometer and helium. It is a non-poisonous and non-flammable gas, even when combined with other gases, which gives it a clear advantage when it comes to ensuring safety during the leak test of the system.
Other filters for choosing accessories
In the TME catalogue, you can sort the available components according to: operating temperature, power consumption, supply voltage, mounting hole size and more. This provides you an opportunity to choose perfect components for a specific project.
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