Italian ATOS relief valves in stock

Brand

ATOS/Italian Atos

ATOS Piston Pumps, ATOS Gear Pumps, ATOS Axial Piston Pumps, ATOS Vane Pumps, ATOS Cylinders, ATOS Relief Valves

ATOS Relief Valve Daily Operation Precautions

ATOS relief valves are hydraulic pressure control valves. In hydraulic equipment, they mainly function as constant pressure relief valves and provide safety protection.

Main function of ATOS relief valves: Constant pressure relief function: In a fixed displacement pump throttling system, the fixed displacement pump provides a constant flow rate. When the system pressure increases, the flow demand decreases. At this time, the relief valve opens, allowing excess flow to overflow back to the oil tank, ensuring that the inlet pressure of the relief valve, i.e., the pump outlet pressure, remains constant (the valve opening often fluctuates with pressure).

ATOS Relief Valve Noise and Vibration

Components in hydraulic systems that are prone to noise are generally considered to be pumps and valves, with relief valves and solenoid directional valves being the main types of valves. Many factors contribute to noise generation. The noise from relief valves includes flow velocity noise and mechanical noise. The noise generated by the flow velocity is mainly due to oil vibration, cavitation, and hydraulic shock. The noise generated by the mechanical components is mainly due to the impact and friction of the valve parts.

(1) Noise caused by uneven pressure

The pilot valve section of the ATOS relief valve is a vibration-prone part, as shown in Figure 3. During high-pressure overflow, the axial opening of the pilot valve is very small, only 0.003~0.006 cm. The flow area is very small, and the flow velocity is very high, reaching 200 m/s, which easily causes uneven pressure distribution, resulting in an imbalance of radial force in the cone valve and vibration. In addition, the ellipticity generated during the machining of the cone valve and cone valve seat, dirt adhering to the pilot valve port, and deformation of the pressure regulating spring can also cause vibration of the cone valve. Therefore, the pilot valve is generally considered the source of noise.

Due to the presence of elastic elements (springs) and moving mass (cone valve), a condition for oscillation is created, and the front cavity of the pilot valve acts as a resonant cavity. Therefore, vibration of the cone valve easily causes resonance of the entire valve, generating noise. This noise is usually accompanied by severe pressure fluctuations. (2) Noise from Cavitation

When air is drawn into the oil for various reasons, or when the oil pressure is lower than atmospheric pressure, some of the dissolved air in the oil will precipitate and form bubbles. These bubbles are larger in low-pressure areas, but when they flow with the oil to high-pressure areas, they are compressed and their volume suddenly decreases or the bubbles disappear; conversely, if the volume is smaller in high-pressure areas, it suddenly increases when flowing to low-pressure areas. This rapid change in the volume of bubbles in the oil generates noise, and because this process occurs instantaneously, it will cause local hydraulic shock and vibration. The pilot valve port and main valve port of a pilot-operated relief valve experience significant changes in oil flow rate and pressure, making cavitation easy to occur, thus generating noise and vibration.

(3) Noise from Hydraulic Shock

When the ATOS relief valve is unloaded, pressure shock noise will occur due to the rapid drop in pressure in the hydraulic circuit. The higher the pressure and capacity of the operating conditions, the greater this impact noise. This is because the unloading time of the relief valve is very short, resulting in hydraulic shock. During unloading, the oil flow rate changes drastically, causing a sudden pressure change and creating a pressure wave impact. The pressure wave is a small shock wave, and the noise it generates is very small. However, as it travels through the system with the oil, if it resonates with any mechanical part, it can increase vibration and enhance noise. Therefore, hydraulic shock noise is usually accompanied by system vibration.

(4) Mechanical Noise

The mechanical noise emitted by the ATOS relief valve generally comes from the impact of parts and the friction of parts caused by machining errors, etc.

In the noise emitted by the pilot-operated relief valve, there is sometimes a mechanical high-frequency vibration sound, generally called self-excited vibration sound. This is the sound produced by the high-frequency vibration of the main valve and the pilot valve. Its occurrence rate is related to factors such as the configuration of the return oil pipeline, flow rate, pressure, and oil temperature (viscosity). Generally, the smaller the pipeline diameter, the lower the flow rate, the higher the pressure, and the lower the oil viscosity, the higher the occurrence rate of self-excited vibration. DKZOR-A-173-D5

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