German DONADON SDD valves, DONADON SDD models, DONADON SDD prices

DONADON SDD 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.

DONADON SDD Valve Classification

Throttle valves can be classified into straight-through and angle types based on the flow path configuration. Based on the shape of the closing element, there are three types: needle, groove, and window. 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 for 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 a long service life and significantly improved flow regulation accuracy. It is applicable to industries such as petroleum, natural gas, chemical, refining, and hydroelectric power.

DONADON SDD 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 the actuator load variation is very small and speed stability requirements are not high. For throttle speed control systems with large 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.

DONADON SDD Valve Installation and Maintenance

The following points should be noted during the installation and maintenance of throttle valves: This valve requires frequent operation, so it should be installed in a location that is easy and convenient to operate. During installation, ensure that the direction of the medium aligns with the arrow direction marked on the valve body. 1) Mechanical impurities in the oil, or contaminants such as gum, asphalt, and carbon residue precipitated by oxidation, accumulate at the throttling 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 throttling gap, polarized molecules are adsorbed onto the gap surface, forming a firm boundary adsorption layer. The thickness of this adsorption layer is generally 5~8 microns, which affects the size of the throttling gap. When these accumulations and adsorbates grow to a certain thickness, they are washed away by the fluid flow and then re-attach to the valve port. This cycle results in flow pulsation. 3) When the pressure differential at the valve port is large, the temperature at the valve port is high, increasing the degree of liquid compression. The metal surface is more susceptible to friction, creating a potential difference. Therefore, blockage phenomena are more likely to occur under high pressure differentials. 4) Source of PCV exhaust gases: Combustible mixture from the combustion chamber enters the crankcase through piston gaps, 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 reduction. The "unstable components" oxidize and condense at high temperatures, forming oil sludge that adheres to the throttle valve surface. 5) Lubricating oil penetrating deep into 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, boosting intake airflow. However, under long-term and harsh operating conditions, the common shaft bearings are prone to lubricating oil penetration and volatilization. Coupled with doubled 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 continuous high temperatures, it can oxidize and condense to form gummy oil sludge.

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