German AVK valves, AVK models, AVK prices

AVK 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 fixed-displacement pump hydraulic systems, throttle valves used 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 lack negative flow feedback and cannot compensate for speed instability caused by load changes; they are generally used only in applications with minimal load variation or low requirements for speed stability.

AVK Valve Classification

Throttle valves are classified by flow path as straight-through or angle type; by the shape of the closing element, they are classified as needle, groove, or window type. Adjustable throttle valve: The valve needle and spool are made of hard alloy. The product is designed according to API6A standards and features wear and erosion resistance. It is mainly used in wellhead oil (gas) tree equipment. Sleeve-type throttle valve: The spool adopts a low-noise balanced structure for easy opening. The product is designed according to API6A standards. The spool 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 in industries such as petroleum, natural gas, chemical, refining, and hydropower.

AVK Valve Applications

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

AVK 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 to access and operate. During installation, ensure the medium flow direction aligns with the arrow marked on the valve body. 1) Mechanical impurities in the oil, or contaminants such as gum, asphalt, and carbon residue precipitated by oxidation, accumulate in the throttling gaps. 2) Polarized molecules generated by oil aging or compression become charged. A potential difference exists on the metal surfaces of the throttling gaps, causing polarized molecules to adsorb onto the gap surfaces, forming a firm boundary adsorption layer. The thickness of this layer is generally 5~8 micrometers, affecting the size of the throttling gap. When these accumulations and adsorbates reach a certain thickness, they are washed away by the fluid flow and then re-attach to the valve port. This cycle creates flow pulsation. 3) When the pressure differential across the valve port is large, the temperature at the port is high, increasing the degree of liquid compression. The metal surface is more susceptible to friction-induced potential differences, making clogging more likely 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 Crankcase Ventilation system (PCV) for secondary combustion. After entering the intake manifold, the lower temperature causes condensation into a liquid phase. 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: Turbocharged engines commonly use exhaust-driven turbines, where high-pressure exhaust from the exhaust manifold drives the turbine, which coaxially drives the compressor blades in the intake manifold to boost intake airflow. However, under long-term and harsh operating conditions, the coaxial bearings are prone to lubricating oil penetration and volatilization. Combined with doubled charging efficiency, this facilitates the formation of heavy oil stains, exacerbating deposit adhesion on the throttle valve body. 6) Fuel vapor discharged from the carbon canister: Among the fuel vapors adsorbed by the engine's 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 gel-like oil sludge.

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