Noise Control in Hydraulic Systems
When hydraulic systems do not receive the routine maintenance they need, they become vulnerable to a number of major performance problems. Few of these issues are more annoying than excessive noise.
A noisy system not only creates unnecessary disruptions in the workplace, it’s also the symptom of a potentially severe mechanical issue. Therefore, a hydraulic system that keeps emitting loud vibrations, knocking sounds, or other hard-to-ignore noises should be inspected at the earliest opportunity so the problem can be located and properly corrected.
Let us take this opportunity to explore in more detail the problem of hydraulic noise control.
Why Noise Control Is Important
A hydraulic system that won’t stop emitting strange noises is an irritation that no one should have to endure, as it tends to disrupt the concentration and peace of mind of personnel who work in the area.
If the problems associated with system noise were no more serious than this, however, they would not constitute an issue that would merit more than cursory attention. This is not the case, though—noise can literally damage one’s health. Noise-induced hearing loss, as it is called, is not a matter to be ignored. People who routinely work in noisy environments can, and sometimes do, lose hearing capacity over time.
An excessively noisy hydraulic system may even violate the law. In the U.K., employers are required to ensure that workplaces do not have pieces of equipment that generate excessive noise levels. The relevant legislation is the Control of Noise at Work Regulations 2005.
Aside from these considerations, noise may indicate major functional issues with the system. Noise is often the product of system malfunctions that can cause significant damage to one or more components. For example, a component prone to noisy vibrations may harm another component that wasn’t designed to tolerate such activity. If the system is not inspected properly, these issues may worsen over time. In the worst case scenario, catastrophic failure may result.
Where Noise Originates in a Hydraulic System
Now that we’ve established the need to correct system problems that cause noise, we need to be able to locate the source of all that din. In many cases, the noise has multiple sources, as various components emit relatively low levels of sound that meld together to create a cacophonous racket.
Reducing the overall noise to an acceptable level doesn’t necessarily involve repairing all noise-making components—it’s often enough to fix only one or two parts. The goal is not to bring about a completely noise-free system. It’s only necessary to reduce noise in compliance with the law, the mechanical needs of the equipment, and the comfort level of personnel in the area.
Although noise can emit from many areas along the system, the most common cause is a defect with the pump(s). Noise may be generated by the mechanical motion of the unit (e.g., the bearings) and/or the movement of the hydraulic fluid through the pump. If you’re searching for the source of system noise, it’s a good practice to start with these components.
Another frequent culprit is the electric motor connected to the pump. Fluid conductors such as hoses and tubes can also generate excessive noise if these components are worn out or improperly connected to the system. Later on, we’ll explore some specific tips for pinpointing issues with these kinds of parts.
Common Causes of Hydraulic Noise
There are a few common physical phenomena that lead to excessive noise levels in a hydraulic system.
Aeration – The presence of air in the hydraulic fluid is known as aeration, and it can trigger serious problems. Aeration can lead to a reduction inf fluid quality, compromising its ability to lubricate moving parts and prevent overheating. Pockets of air in the system tend to make a loud knocking or banging noise as they travel through the hydraulic system.
Cavitation – When a hydraulic system fails to provide a sufficient amount of fluid to a particular area, vapor bubbles (or cavities) can form. This is known as cavitation. An increase of system pressure makes the cavities implode, generating a shock wave. Cavitation in a hydraulic system makes a distinctive knocking sound—but the problem is more serious than mere annoying noises. The imploding cavities can harm system components, possibly causing them to fail altogether.
Strategies to Reduce Hydraulic Noise
Here we’ll explore a handful of specific suggestions for identifying and correcting noise in the system. This is not a comprehensive guide to noise mitigation, but it does highlight some common issues that often plague this type of equipment.
Check the Hoses – Improperly configured hoses are a frequent cause of excessive noise in hydraulic systems. The problem develops when the hose is bent at a sharp angle in order to connect it properly. Bent hose, however, tends to generate noise, significantly more than straight hose does. You may be able to reduce noise levels dramatically simply by replacing these bent hoses with metal tubing, which will not generate as much racket. If it is the inlet hose that is bent, oil supply may become restricted by the end leading to noise as a result of pump cavitation.
Check the Electric Motor – The cooling fan in the motor may be contributing to the noise emanating from your hydraulic system. Bi-directional fans produce more racket than ones designed to move in one direction. If you have a fan of the former type, it may be worth the expense of replacing it with a uni-directional fan. It may also be that the fan cowling is blocked or the motor bearings are needing to be replaced.
Pumps—even brand-new modern pumps—produce a certain amount of vibration that generates noise. Reducing these vibrations can substantially contribute to your efforts to solve your noise problem. How can you go about achieving this? An accumulator teed into the pressure line is an excellent shock absorber that has the effect of dampening noise. If your system already has an accumulator, check it to ensure that nothing is amiss—keep in mind that these units require periodic maintenance. You may also wish to change the type of accumulator in your system, as each kind has its own particular advantages. Accumulators are available in three basic types: piston, bladder, and diaphragm. Bladder accumulators are known for their fast response time, while piston accumulators are capable of managing a higher gas compression ratio.
Check the Pump Intake Lines – As we mentioned earlier, aeration is a potentially serious issue. When air gets into the system, it often does so via the pump intake lines, so you should examine these to ensure that they are properly connected and still in acceptable condition.
Check the Reservoir – Low fluid level in the reservoir could trigger the development of vortex that sucks air into the system, in turn leading to aeration and the noise issues associated with this phenomenon. Filling the reservoir properly can help prevent this problem.
Check the Pump Speed – Reducing the pump speed, when possible, helps to reduce the amount of noise produced by this device. Adding more pumps to the system may allow you to run them at a lower speed without interfering with performance. Figuring out how many pumps to use at which speed can be problematic, so make sure that you have considered all variables before proceeding.
To a large extent, the task of reducing hydraulic system noise requires using high-quality components and performing routine maintenance checks to ensure that everything is in good working condition. White House Products Ltd. is a reliable resource for many organizations across the U.K. that need state-of-the-art hydraulic parts and components. Please explore our online catalog for first-class products from the leading manufacturers active today. Please contact us with any questions you have about our range—we will respond as soon as possible.
Contact White House Products today for more information about our products and services.
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