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Electrostatic charge builds when there are two bodies moving and creating friction. The fact is that this also occurs in hydraulic systems from the friction caused by system components with moving fluid.
Although we haven’t had a lot of situations that have involved electrostatic discharge, it is still something that every engineer should be aware of.
When an electrostatic discharge occurs, there is a clicking noise as charge increases and is then released. This is something that will often occur in a filter – leaving burn marks and potentially other damage.
With the increasing preference of using non-metallic additives in hydraulic oils the electrostatic charge could be on the increase. Those hydraulic oils that contain anti-wear additives that are zinc-based have considerably high conductivity.
Conductivity in hydraulic oils helps when it comes to moving electrostatic charge around the system. Although zinc-based additives will rarely collect enough charge to cause a big problem, synthetic oils can. This is because they have less conductivity and therefore will potentially accumulate more charge before discharging it.
Another change that could lead to an increase in electrostatic discharge is that there has been a change made to the materials that filter elements are made of. In order to make them easier to dispose of them in an eco-friendly way, they have more non-metallic material in the design, which lowers conductivity and therefore increases the capacitance.
The manufacturers of hydraulic filters are aware of these issues, and are looking into how they can minimise or even eliminate these issues.
However, if you come across a situation where there is electrostatic discharge in the meantime, then consider this:
By adding larger filter elements you can reduce flow density and therefore the amount of charge that is being generated. You might also want to consider increasing the tank size so that the time between charge generations increases.
This is one of the reasons why you shouldn’t skimp on tank size or on filter capacity.
Filters are a small but vital part of hydraulic machinery, although serving no mechanical purpose they are integral to the proper functioning of the machine and to prolonging the active life of the equipment and the hydraulic fluid which drives it. The role of a filter is to remove and/or contain particles of contamination and keep the fluid that flows round the machine clear. Any contamination in the oil can cause damage to moving parts further downstream, and this can lead to seizing up of moving parts, corrosion of other parts and costly replacements. When we consider the consequences of not using a filter, the importance of these little items becomes more significant.
There are two main styles of hydraulic oil filter – surface and depth filters. The surface filter, as the name suggests, removes contamination from the surface of the oil and may be useful in applications where gravity feeds the oil through a space suitable for such a filter during operation. A depth filter can be submerged in a reservoir or chamber and will remove particles from the entirety of the body of fluid. Depth filters therefore, are more effective and will retain a larger amount of contamination and unwanted particles before they need to be cleaned or replaced.
The materials used to make hydraulic filters varies, as does the cost accordingly. Glass filters are more expensive but they are more efficient, especially when glass fibres are used in a depth filter. Glass is also non-reactive, meaning it can be used with any type of hydraulic fluid. Metal filters are also reasonably efficient, but they cannot be used with all types of hydraulic fluid, due to incompatibilities between certain hydraulic oils and some metals. Where it is appropriate to use a metal filter there is the option of a magnetic filter system, which works as a depth filter and uses a magnetic charge to attract metal particles that may have entered the fluid system. If the hydraulic equipment is used in metal working and fabrication then the chance of potential contamination being from metallic particles is high; magnetic filters will deal with this contamination while another type of filter can be used to deal with other types of pollution.
Cellulose or paper can also be used to make a hydraulic fluid filter, but these have a short life expectancy and need frequent replacement. They are cheaper than the other types, but could end up costing more in the long run, due to regular downtime for replacement and the potential damage to machinery if they are not replaced often enough.
It may seem like glass is the best choice; despite costing a little more it does the best job and will not need replacing too often. The drawback of a glass filter is actually its strength as well; the superior filtering ability can actually lead to a drop in pressure, in the system, which is usually undesirable. It is especially important, therefore, to check how a drop in hydraulic system pressure will affect productivity and performance if you are considering switching to glass filters from another material type. Consider also whether this drop in pressure is likely to lead to unnecessary adjustments of pressure relief valves, leading to potentially dangerous build ups of pressure elsewhere.
The options of hydraulic oil filters do not end after material type and construction, as there is still the issue of ratings and specifications to contend with. All filters have an ISO 4406 rating, and the lower the code of any given filter, the better it is at removing contamination. Hydraulic filters may also have a beta ratio, which is the ratio of particles found upstream of the filter divided by the number found downstream. For beta ratios, the higher it is the better, and this can also be used to give a percentage for effectiveness.
It is also important to check that the flow rate of the filter is compatible with the flow rate of the machinery it is to be used in; too fast and the filter will not be able to effectively remove contamination, too slow and it could become clogged quickly. The operational pressure of the hydraulic system is also important, as the filter must be able to withstand that force for a prolonged amount of time. The final thing to check is that the filter can be connected to the equipment, so check the port size of the filter and ensure it is compatible with the machinery in the location it is to be fitted.
There is a lot to consider here, but choosing the most suitable hydraulic fluid filter is an exercise that it is worth spending some time on, as it can make a big difference to the performance and lifespan of your hydraulic equipment and save on downtime and replacement costs in the long run.
It’s no secret that removing particle contamination can greatly increase the life of the components in any hydraulic system. The truth is, is that there are always some particles present, even in brand new hydraulic fluid. How much contamination can be accepted is going to vary depending on the hydraulic system being used.
So how do you go about removing particles in a hydraulic system? If the system is large, then it’s recommended to add filters wherever you feel it’s going to give you the most advantage.
The strange thing about hydraulic system filters is that although they are there to help keep your machine running well, they can sometimes cause damage and shorten the life of your system.
Hydraulic filters run on a rating system that defers to the micron size of the particles being removed. To get the best results, take a sample of your hydraulic fluid so that you have some idea of where you’re starting from and which filters you’ll need. Ideally you’ll flush the fluid before adding new filters so that their main job will be to maintain its cleanliness rather than to clean it up.
No matter where you start from, it’s important to keep in mind that the filters that you use will affect pressure and it could drop it by providing restriction. If this occurs, then it’s possible that the bypass valve on the filter will open and therefore filtering will not be implemented.
If you’re an engineer who has the responsibility of deciding where to put the filters, it’s critical to do this with a mind to prevent any harm from occurring. There’s no point in delivering cure that is worse than the disease.
Here’s our take on what you need to know about where to fit filters on hydraulic systems:
Pressure line. Many components that are located downstream will benefit from positioning the filter in the pressure line. It’s possible to capture as small as 2 microns or less as the pressure will help as it forces the fluid through the filter. However, it’s possible that the filter will be reduced by the high flow velocities which can loosen up trapped particles. In the long term its pressure filtration that costs the most to maintain and the most to get going with.
Return line. The most effective principle to apply to this is that if you start out with a reservoir full of clean fluid, then keeping fluid clean by filtering it will keep it that way. Another benefit of using the return line to add a filter is that you’ll gain advantage from the higher pressure. It’s possible to gain good filtering results at a relatively low cost as there won’t be filter or housing design complications with a pressure of that measure. In actual fact, the lower flow will deliver a filtration that is efficient and low cost. The only disadvantage of this method is that there is a chance of the back pressure causing some issues.
Off line. Filtering your fluid using the off-line method will provide you with a continuous filtration that is multi-pass. The results are excellent filtering efficiency where you can pull out particles that are 2 microns or less in size. It’s also possible to extract water and even heat in order to give your fluid total conditioning. However, there is a cost disadvantage when starting out with this method, but this can usually be reclaimed over the life of the machine.
Suction. Positioning a filter next to the pump intake can provide advantages gained by not being in a high pressure area, however, it does have potential to cause some issues with regards to pump life.
Filtering is important in any hydraulic system and it’s not just about what you use, it’s about where you put it.
Hydraulics has been around for a very long time. But are you aware of how far it has actually come? You wouldn’t be alone if you responded with no. It is a very technical subject that can be quite difficult to understand, but in this article we want to tell you the story of hydraulics! We want to share with you who discovered hydraulics, what it was originally used for and how hydraulic power got to where it is today.
So why don’t we start at the beginning! Where does the word hydraulic come from?
The word hydraulic originates from the Greek word ‘Hydros’ which means water. Why water? Well, this is because water was the first liquid to be used in the hydraulic system. Today, hydraulics includes the physical behaviour of all liquids, not just water.
In the world of industrial, mobile and aerospace equipment, hydraulic power systems are very popular. They enjoy a high power-to-weight ratio in addition to being able to be stalled, operated intermittently and even reversed. They can also accelerate fast and are quick to respond. Another attractive feature of the fluid power system is that they can be very long lasting in addition to offer reliable operation rates.
Hydraulic systems are able to work as they contain incompressible liquid. In many situations, it’s much preferred to use hydraulics to move machinery. For one, fluid systems do not produce the same amount of wear as a dryer method would. It also does not require so many moving parts as a different type of system would.
The pressure of fluid in the hydraulic system is controlled by the valve. They also handle the flow rate and which way the flow is going. The funny thing about hydraulic valves is that they can change name depending on how they are being used and according to which system that are part of. Used in combination with cylinders and hydraulic pumps to control the flow of liquid, hydraulic valves are powerful.
The classification of hydraulic valves is determined by how much pressure they can handle. It is also related to the flow and how many directional control valves there are in them. They may also be classified on their looks and extra features such as needle valves, spools and poppets.
Apart from their ability at moving very heavy objects, one of the reasons that hydraulic systems are so popular is because they can operate at very low noise levels. In the manufacturing industry, a low noise level is sought after, in particular at less than 70dB. The hydraulic system and pump is able to accomplish this.
The hydraulic control valve is a clever piece of kit. Browse hydraulic valves here.
Although hydraulic systems must be lauded for the amazing technological innovation that it is, there are also some other points that you need to know.
When it comes to cars, there are a variety of ways that hydraulics brought benefits from their invention and use. For example, if you have a flat tyre you will reach for the jack to lift up your car to change the tyre. In more modern times the hand cranked device has evolved into the hydraulic jack. Not only does it save your own energy to use these devices, but it will also save time. (FYI here at HydraProducts we have experience in the automotive industry and design hydraulic drive shafts for Mondeo cars).
Another car related hydraulic use is that of hydraulic brakes. The power of the hydraulic system means that there is considerably greater stopping power than that delivered through other braking methods. Car designers are increasingly making use of hydraulics when it comes to back doors and closers. Doors on large vehicles used to difficult to open and close, but with an automatic closer vehicle owners that have their hands full of shopping or other items can conveniently operate this feature for easy access and use of their boot.
It’s not only with cars that hydraulics have entered into all areas of our lives. There are also other tools such as pulleys and levers.
However, for the lay person there are also some risks. For example, hydraulics can easily crush fingers and hands due to their power. A child’s hand in the wrong place at the wrong time can be hurt if a hydraulic powered door were to close on it.
It’s also important to know that the fluid in hydraulic systems can also be made up of very dangerous chemicals. They can cause burns if they touch human skin, although not every substance is harmful, it’s wise to pay attention to leaks and potential leaks.
Hydraulic systems that are not carefully designed and manufactured can cause injury if not handled safely.
All our designs take safety into mind as much as possible. We also make bespoke hydraulic systems for applications that can benefit from hydraulic power.
Hydraulic filtration is a vital component of keeping a system running smoothly.
For example, did you know that up to 75% of failures with fluid power can be attributed to contamination? With the use of hydraulic filters, contamination damage can be significantly lowered which can not only cut down on expense but lower that 75% drastically.
If you’re looking to save costs from less downtime then it’s also time you looked into what a difference hydraulics filtration can make for extending the life of your equipment. Running your system optimally is essential when it comes to cost saving, but protecting its longevity is also a critical element in running any business efficiently.
Muck and dust can destroy a hydraulic system, that’s why it’s essential to make the best use of hydraulic filters. You wouldn’t even be able to remove that dirt yourself, as it’s likely to be dust that is so fine that you won’t be able to see it without the use of a microscope. Dirt has the same detrimental effect as sandpaper or gravel and not only will generally deteriorate the system, but it could even destroy it.
However, through the use of a hydraulic filter system you will be able to maintain control over the level of contamination and by doing so reduce the failure of systems by as much as 75% just be removing that dirt.
Hydraulic parts are expensive. Combine that with down time and having to keep engineers on hand to fix worn components and that’s a lot of expense to deal with. Putting filters into place can even save costs by increasing how long the hydraulic fluid will last.
Degradation of fluid – hydraulic fluid that contains fine metallic particles can degrade rapidly through chemical breakdown. Without protecting against this, there could be issues such as slippage, internal leakage, corrosion or sticking parts.
Scoring of surfaces – this can occur when particles get trapped between surfaces of seals
There’s no doubt about it, but …
· System performance is affected by dirt levels
· Hydraulic filters can control levels of dirt. Without using this management method, the system will get dirtier and dirtier until it fails.
In fact, hydraulic filters are the only way to control how much dirt is in fluid. Without them you will be forced to change out the hydraulic fluid regularly, which can be a time consuming and costly event.
Hydraulic system dirt particles are incredibly small. In fact, they are so small that they cannot be seen by the human eye – and 98% of hydraulic fluid has some dirt in it.
Engineers have found that when it comes to size of particles in samples taken from operating systems, the smaller the particles, the more dirt there is in the system.
So where do these particles come from that we have to work so hard to deal with?
In order to have an idea of what goes on inside the closed system, let’s examine where these particles come from.
Instead of enjoying the typical 20 gpm that is the measurement of a pumped flow from a 2000 psi system, you can expect to see something in the region of just 10 gpm. Although your pump will still produce for you, you’ll discover that the degradation results in just 50% efficiency and you should als be prepared to experience extra heat and other unwanted issues.
As with any hydraulic system, there is an optimum level of cleanliness, but there is a point where you cannot get any better performance out of the system by improving the quality of the fluid. However, with the use of hydraulic filters you should be well set to extend the life of your machinery.
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