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A Guide to Hydraulic System Noise Reduction ben lee

If your hydraulic system is making far too much noise for the comfort of your peers, your boss and/or the workplace noise reduction plan, then it’s time to take action. Let’s look at what’s possible when it comes to reducing it.

It’s common for developed countries to have some regulations when it comes to workplace noise levels. Industrial hydraulic systems are often the target of efforts to lower noise due to their high noise emission because they’re a high power density machine. Noise radiation is affected by its area and its mass. Therefore, decreasing the surface area of an object or increasing its mass can reduce it. There are several ways to approach this, including the possibility of using thicker plate on the hydraulic reservoir so as to increase its mass.

The usual culprit when it comes to hydraulic system noise is the pump. Not only does it radiate noise into the air, but it also has noise being emitted from both its structure and its fluid. Pumping chambers are present in all positive-displacement hydraulic pumps. They need to be filled and then they need to expel contents with plenty of closing inlets and outlets to control these functions. A pulsating delivery is produced from these flows, that are separate albeit overlapping and they cause pressure pulsations. The pressure pulsations create fluid-borne noise which can then lead to vibration of any downstream components. There is also other noise passing through the structure and the air.

By smart hydraulic pump design, some of the fluid-borne noise can be decreased, although not completely disposed of. In very large systems, it may be possible to install a silencer. The most basic but effective of these is the reflective silencer which stops sound waves by overlapping another soundwave that is the exact opposite in amplitude and frequency of the first.

It’s also possible to decrease noise by ensuring that there are no bridges to carry the sound of the vibrating mass of the power unit. The tank and/or the valves and the power unit cause the most issue, but by changing the connections to flexible connections such as rubber hoses and mounting blocks, it is possible to decrease the vibration and therefore, noise. In some cases, the best approach is to introduce more mass, so that the transmission of vibration is reduced at bridging points.

The area and mass of an object is what influences the significance of noise radiation. By either reducing the surface area of the object or even increasing its mass, noise can be reduced.  For example, by changing the construction of the hydraulic reservoir to be of thicker plate, the increase in mass will effect noise radiation and reduce it.

There is also an opportunity to reduce air-borne radiated noise through mounting the pump inside the reservoir tank. Ideally there would be a 50cm clearance between the side of the tank and the pump for this to be fully effective. It’s important to include a decoupling on the mounting assembly so as to provide some insulation against structure-borne noise. However, there is one rather large disadvantage to this solution, and that is the difficulty of reaching the pump for adjustment and maintenance purposes.

If after everything you have done, you are still suffering from too much noise emanating from your hydraulic system, there is still a solution for you. You can encapsulate or screen the hydraulic system so as to insulate it. In summary, it’s often errors in design that result in exaggerated noise from hydraulic machines.  You can modify them to reduce the noise, or you can screen them for insulation.

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