German EWO valves EWO models EWO prices

EWO valves are valves that control fluid flow by changing the throttling cross-section or throttling length. Connecting a throttle valve and a check valve in parallel forms a one-way throttle valve. Throttle valves and one-way throttle valves are simple flow control valves. In hydraulic systems with fixed-displacement pumps, throttle valves used in conjunction with relief valves can form three types of throttle speed control systems: inlet throttle speed control, return line throttle speed control, and bypass throttle speed control. Throttle valves do not have negative flow feedback functionality and cannot compensate for speed instability caused by load changes; they are generally only used in applications with minimal load variation or low requirements for speed stability.

EWO Valve Classification

Throttle valves can be classified into straight-through and angle types based on flow path configuration; based on the shape of the closing element, there are needle, groove, and window types. Adjustable throttle valve: The valve needle and valve core are made of hard alloy. The product is designed according to API6A standards and features wear resistance and erosion resistance. It is mainly used for wellhead oil (gas) tree equipment. Sleeve-type throttle valve: The valve core adopts a low-noise balanced structure, allowing easy opening. The product is designed according to API6A standards. The valve core surface is coated with tungsten carbide, making it suitable for harsh conditions such as flashing, high pressure differential, high pressure, and cavitation. It offers long service life and significantly improved flow regulation accuracy. It is applicable to industries such as petroleum, natural gas, chemical processing, oil refining, and hydropower.

EWO Valve Applications

Since the flow rate of a throttle valve depends not only on the size of the throttling orifice area but also on the pressure differential before and after the orifice, and due to the low stiffness of the valve, it is only suitable for applications where actuator load changes are minimal and speed stability requirements are low. For throttle speed control systems with significant actuator load variations and high requirements for speed stability, pressure compensation must be applied to the throttle valve to maintain a constant pressure differential across the valve, thereby achieving stable flow.

EWO Valve Installation and Maintenance

Precautions for the installation and maintenance of throttle valves: This valve requires frequent operation, so it should be installed in a position that is easier to access and operate. During installation, ensure that the flow direction of the medium aligns with the arrow direction marked on the valve body. 1) Mechanical impurities in the oil, or contaminants such as gums, asphaltenes, and carbon residues precipitated due to oxidation, accumulate at the throttle gap. 2) Due to oil aging or compression, charged polarized molecules are generated. Since there is a potential difference on the metal surface of the throttle gap, these polarized molecules are adsorbed onto the gap surface, forming a firm boundary adsorption layer. The thickness of this adsorption layer is generally 5~8 micrometers, thereby affecting the size of the throttle gap. When the accumulated adsorbates reach a certain thickness, they are washed away by the fluid flow and then re-attach to the valve port. This cyclic process results in flow pulsation. 3) When the pressure differential across the valve port is large, the temperature at the valve port is high, increasing the degree of liquid compression. The metal surface is also more susceptible to friction-induced potential differences. Therefore, blockage is more likely to occur under high pressure differentials. 4) PCV exhaust gas source: Combustible mixture from the combustion chamber enters the crankcase through the piston clearance, mixes with oil vapor, and forms a mixed gas. To avoid diluting and contaminating the engine oil, this mixture is drawn into the intake manifold by the Positive Crankcase Ventilation (PCV) system for secondary combustion. After entering the intake manifold, this portion of exhaust gas condenses into a liquid phase due to temperature drop. Its "unstable components" oxidize and condense under high temperatures, forming oil sludge that adheres to the throttle valve surface. 5) Lubricating oil penetrating from the turbocharger compressor: For turbocharged engines, exhaust gas drive is commonly used, where high-pressure exhaust from the exhaust manifold drives the turbine, which in turn drives the compressor blades in the intake manifold via a common shaft to boost intake airflow. However, under long-term and harsh operating conditions, the common shaft bearings are prone to lubricating oil seepage and volatilization. Coupled with multiplied charging efficiency, this facilitates the formation of heavy oil fouling, exacerbating the adhesion of deposits on the throttle valve body. 6) Fuel vapor discharged from the carbon canister: Among the fuel vapors adsorbed by the engine carbon canister, cyclopentadiene is the primary component that forms deposits on the throttle valve. Under sustained high temperatures, it can oxidize and condense to form gummy oil sludge.

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