German LVF valve LVF model LVF price

LVF valves are valves that reduce inlet pressure to a required outlet pressure through regulation, and rely on the energy of the medium itself to automatically maintain stable outlet pressure. From the perspective of fluid mechanics, a pressure reducing valve is a throttling element with variable local resistance, i.e., by changing the throttling area, the flow velocity and kinetic energy of the fluid are changed, causing different pressure losses, thereby achieving pressure reduction. Then, through the regulation of the control and adjustment system, the fluctuation of the pressure after the valve is balanced with the spring force, keeping the pressure after the valve constant within a certain error range.

LVF valve working principle

The pressure reducing valve reduces water pressure by the local resistance of the flow channel inside the valve to the water flow. The range of water pressure drop is automatically adjusted by the water pressure difference between the inlet and outlet on both sides of the diaphragm or piston connected to the valve disc. The fixed-ratio pressure reduction principle uses the water pressure ratio of the floating piston in the valve body for control; the pressure reduction ratio between the inlet and outlet ends is inversely proportional to the area ratio of the pistons on the inlet and outlet sides. This type of pressure reducing valve operates smoothly without vibration; there is no spring inside the valve body, so there is no concern about spring corrosion or metal fatigue failure. The sealing performance is good with no leakage, thus reducing both dynamic pressure (when water is flowing) and static pressure (when flow rate is 0); especially, it reduces pressure without affecting the water flow rate. The pressure reducing valve regulates the flow of the medium by adjusting the opening degree of the closing member inside the valve body, reducing the pressure of the medium, while simultaneously adjusting the opening degree of the closing member by the action of the pressure after the valve, keeping the pressure after the valve within a certain range, and injecting cooling water inside the valve body or after the valve to reduce the temperature of the medium; this type of valve is called a pressure reducing and desuperheating valve. Kuaiyiyou Automation Selection includes pressure reducing valves. The characteristic of this valve is to keep the outlet pressure and temperature value within a certain range when the inlet pressure changes continuously.

LVF valve installation precautions

1) Before installing the valve, carefully verify whether the model and specifications of the valve used match the design; 2) Check against the valve model and factory instruction manual to determine if the valve can be applied under the required conditions; 3) When lifting the valve, the rope should be tied at the flange connection between the valve body and the valve cover, and must not be tied to the handwheel or valve stem, to avoid damaging the valve stem and handwheel; 4) When installing the valve on a horizontal pipe, the valve stem should be vertically upward; downward installation of the valve stem is not allowed; 5) When installing the valve, do not use forced alignment connection methods such as pulling or dragging hard, to avoid damage caused by uneven stress; 6) Rising stem gate valves should not be installed in underground damp places to avoid corrosion of the valve stem.

LVF valve troubleshooting

In certain pressure reducing control circuits, the outlet pressure of the pressure reducing valve is used to control the pressure level of the control oil for electro-hydraulic directional valves or externally controlled sequence valves, etc. When the electro-hydraulic directional valve or externally controlled sequence valve shifts or operates, the flow rate at the outlet of the pressure reducing valve becomes zero, but the pressure must still maintain the originally set pressure. In this case, since the flow rate at the valve outlet is zero, the flow passing through the pressure reducing port is only the pilot flow. Since the pilot flow is very small, generally within 2L/min, the main valve pressure reducing port is basically close to the fully closed position (extremely small opening), and the pilot flow exits from the triangular groove or inclined conical surface. If the fit of the main valve spool is too loose or the wear is excessive, the leakage increases. According to the continuity theorem of flow, this part of the leakage must also flow from the damping hole of the main valve spool, meaning the flow through the damping hole consists of two parts: the pilot flow and the leakage. Since the area of the damping hole and the oil pressure in the main valve spring chamber remain unchanged (the oil pressure in the spring chamber is determined by the pre-compression amount of the already adjusted pressure regulating spring), an increase in the flow through the damping hole will inevitably cause the oil pressure in the lower chamber of the main valve to rise. Therefore, after the outlet pressure of the pressure reducing valve is set, if the outlet flow is zero, the outlet pressure will rise due to excessive looseness or wear of the main valve spool fit.

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