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One would think that new hydraulic oil that is in a sealed container would be clean. However, surprisingly, and somewhat disappointingly, this is not always the case.
Oil can easily become contaminated during the process of distribution. Although some oil is packaged within the factory or blending facilities, some oil may be sent out to bulk oil distributors in containers such as a railway tanker or a tanker truck. Although there are oil dedicated tanker systems in existence, they are not allocated to specific products. For example, motor oil may have been in a tanker before hydraulic oil is shipped in it.
At local distributors, oil will be stored at bulk storage facilities and then decanted to plastic bottles and drums with plastic seals added.
It’s at this point that hydraulic oil could meet with cleaning products that were used in drums to prevent contamination. Also, the oil will have been handled several times and therefore it’s more likely to have been contaminated.
If you buy in bulk and it’s delivered to your facilities in a container, there’s a chance that your hydraulic oil will pass through pipes and nozzles that were not flushed very well before use. They may have had some remnant of the previous products in them, such as 15W40 motor oil. This could end up in your storage facilities, and ultimately in your hydraulic system.
Now it’s a question of how clean your storage and dispensing facilities are. Are they sealed so as not to allow particle contamination? Are they exposed to extreme temperature level changes or too external elements or flushed with water from a hose?
Of course, you should really know some of the answers to this, but it’s quite likely that you don’t. However, you can take an oil particle count analysis to measure your contaminants. You could be surprised at the results and how they differ from what you expect.
Are you interested in what can cut costs when it comes to Hydraulic Power in your business?
We can only imagine that the answer is ‘yes’ as most of us are. Well, we’ve got some good news for you. Today, we’re going to look at what the most common reasons are that hydraulic components fail, even those that have not been in service for long.
These points are worth making a note of:
1. Oil changes. It’s not necessary to keep changing the oil unless you have one of thes2 following conditions occurring.
The oil has degraded so far that the original additives have changed its makeup. Changing oil just because you feel it’s about time it’s changed is going to cost you a lot of outlay as oil is expensive. The larger your reservoir, the worse off you’ll be. However, if you keep operating your system with degraded oil, then that could cost you even more. Even changing the oil based on how long it’s been in service isn’t going to help. Oil needs to be analysed to fully understand its condition.
If you discover that your oil is contaminated with particles, the more economical manner to deal with this is to remove the particles through filtration.
So in summary, only change the oil when the additives have been depleted and the base oil is useless. You will have to perform oil analysis to make your decision.
2. Filter changes. It’s the same story with hydraulic filters. Changing them based on hours in service could mean that you’re too early or even too late. Early brings about waste as their capacity is not reached and you’ll be throwing away an unused amount of filter time. Changing them late is also an error as the particles will not be removed from the oil and therefore, it could lower the lifespan of each component in the entire hydraulic system.
The most effective approach is to only change filters once they have become full of dirt, but prior to the bypass valve opening. This may require a mechanism to be added that will monitor the pressure and deliver an alert when a point is reached. A clogging indicator is one of the most basic methods of handling this. However, continuous monitoring of pressure drop through the use of a differential pressure gauge or a transducer is the optimal solution. In summary, changing filters on hours is not maintenance effective, or cost effective.
3. Heat. If you’re driving along and you notice that your car engine is overheating, you would most likely stop. Most equipment owners won’t run an engine that is overheating. They know it’s going to cause problems. However, the same cannot be said about operators of hydraulic system.
Just as with a car, running an overheated engine is the quickest way to destroy hydraulic seals, hoses and other components. How hot is too hot? The answer depends on the viscosity of the oil in addition to the hydraulic components. Viscosity lessens with increasing temperature, so the answer is when the temperature is high enough to stop the oil lubricating as it should.
When it comes to hydraulic components, it’s worth noting that a vane pump needs more viscosity than a piston pump would. If you have a vane pump in your hydraulic system, then you’ll want at least 25 centistokes to be maintained.
Temperatures over 82°C will cause damage to seals and hoses in addition to accelerating the oil’s degradation. Never allow your hydraulic system to operate above 82°C with a viscosity lower than 10 centistokes.
4. The wrong oil. The most important element of any hydraulic system is always the oil. It’s what keeps everything lubricated and it is also what transfers the power. With these two major tasks to handle, keeping an eye on viscosity is a must.
The viscosity of the oil is what will determine the temperature at which the system should be run. You may have heard this referred to as temperature operating window or TOW. A temperature that is too high will prevent the oil from flowing or lubricating as it should. Oil that has a viscosity that is too low will not deliver adequate lubrication either. Keeping an eye on this will also ensure that you power isn’t lost due to either internal leakage or mechanical friction.
You don’t want increased power consumption as it will cost you more. The best way to handle this is to check what your machines temperature operating window is and to ensure that your machine operates within that window at all times. We won’t go into how to do this here, as it’s rather complex, but it’s something that does need to be addressed.
5. Filter locations. There are two locations for filters that cause the most problems – the piston pump and motor case line and the pump inlet. You may have a strainer attached to the pump inlet to collect any ‘garbage’ in your oil, but this oil is being drawn from a reservoir, not somewhere where there should be any garbage.
The pump inlet is also positioned off the bottom, so there should not be a lot of dirt passing through. By placing filters here, it can affect whether you get maximum pump life. If there is any form of restricted intake, it can reduce the lifespan of the gear pump by as much as half. Hydraulic pumps are not built with ‘sucking’ in mind! The way to handle this is to remove any suction strainers or depth filters on either the pump inlet or the piston pump.
Applying these points should be helpful to any hydraulic system operators and should deliver methods to save yourself and your business great expense.
Until next time..
Although most people are under the impression that new hydraulic system lubricants are clean – this is far from the truth. Unfortunately it’s not every manufacturing process that ensures that no particles are let loose into hydraulic fluids.
At the beginning of every lubricant making process, is the base oil. Then additives are blended in to complete the finished product. It’s then tested to ensure that it works as it should do with the right characteristics. If for some reason, this is not the case then an adjustment is made to bring it in line.
Manufacturers use different ways to blend their hydraulic system lubricant components. Some use a type of blender and others use air to mix it up.
However, it’s important to consider what these additives are and how they are added. For example, are they filtering the additives before adding them? Is the air filtered before being used to agitate the blend? If not, it’s highly likely that they’ll contain particles and / or contaminants.
Once the lubricants are blended, any contaminants should be removed by filtering the liquid. It’s also important that breathers are provided for the lubricant storage tanks. A j-tube vent is not enough.
You should also know whether the blender of the hydraulic system lubricant uses new drums or reconditioned drums and whether there are any self-determined specific cleanliness measurements for them to adhere to. New drums can bring contamination due to their manufacturing process, and reconditioned drums can also bring particles from previous fluids.
If the lubricant is going to be added to a tank, then it should be filtered beforehand. The tank should be of a particular cleanliness. How was it cleaned? With diesel fuel or was it steam cleaned?
As you can see there are many ways that lubricants can be contaminated – by doing your research you can find out a lot and avoid dirty lubricants from entering your hydraulic system.
In today’s post, let’s cover why you need clean hydraulic fluid in your hydraulic system.
If you follow the industry news, you may be aware of a study that was undertaken a few years back on hydraulic fluid and particle contamination. These results were published in a well-known journal on equipment management.
The results of the study produced some fairly alarming statistics such as:
The researchers recognised that even hydraulic fluid analysis testing is not going to detect all the particles that can cause damage. Some of them will enter the system directly from damaged seals, dirty equipment or debris that has built up in the assembly.
It is recommended that particle count testing is used to deliver a more effective analysis of oil. This more sensitive approach for hydraulic oil testing will in fact identify particles that are 2 microns and over. It’s these smaller particles that measure less than 10 microns that will cause the majority of the damage. In fact 3.5 times more damage.
This report clearly shows how important it is to keep hydraulic fluid clean. You may want to discuss this with your service provider and ask about increased filtration and a schedule for particle testing to take place. You will get a longer lifespan from your hydraulic equipment.
If a metal filter is removable, then it’s most likely to be cleanable. In this post we look at how to clean a hydraulic metal filter in the most effective manner. The result should be that you can perform more of your own maintenance and therefore can save on cost of parts and of expertise.
To remove the filter from the filter canister, it’s important to follow the instructions of the manufacturer. Once the filter has been removed, it can then be cleaned, placed back into its position and re-used. Industrial environments are quite often dusty and dirty, and although hydraulic systems are usually closed, you will still need to factor the cleaning task into your regular engineer maintenance schedule to ensure the best performance from your system.
You will need the following pieces of equipment in order to clean your metal filter:
Start the cleaning process by placing the metal filter into the solvent tank. Use the solvent to clean the filter and then rinse it off as you use the small brush to remove any debris and dirt. The solvent will work on dissolving the dirt, so be generous with your application of it. Once the cleaning is finished, you can then shake off the excess solvent from the filter.
Now pour the hydraulic fluid into the bucket and place the filter into it. Now swish the filter in the fluid for a few minutes. This will help to remove any traces of solvent. You can now reinsert the filter into its position.
Keeping your oil filter clean will help to keep the entire hydraulic system cleaner. It’s something that is worth the investment in both trouble and cost.
It’s no secret that hydraulic systems are sensitive to contamination from fluid or oil. Those that are kept clean and protected against the introduction of dirt or water, can run reliably. However, if any contamination is allowed to slip then there will be problems ahead.
Clearances are tight in hydraulic systems and the components such as cylinders, valves and pumps are markedly sensitive. Even a small foreign particle is likely to cause a problem.
Although the layout of hydraulic systems differs from system to system, there are of course the basic elements that are common across the board. For example, the hydraulic reservoir can become home to contaminants or there can be a filtration system employed to clean the fluid.
There is also the pump. Depending on whether a gear pump is in use or a vane or piston pipe that generally have tighter clearances is installed will depend on how much contamination your machine will withstand.
Finally, the flow control valves range in sensitivity, with servo-controlled systems being the most particular. The simpler setups that involve directional or check valves will handle more contamination before failing.
The smartest way to handle the risk and fallout from contamination is to develop a contamination control strategy. This should be built around:
· Control targets determined by your system design
· Detailed actions to ensure that your contamination control targets are met or exceeded
· Measurement by analysis of your oil to check if cleanliness targets are met
Let’s explore these further:
Cleanliness target development
Hydraulic systems suffer most from particular contamination and water contamination. However, heat and air can also have detrimental effects on them. Particles within the range of 1 to 10 microns ideally need to be captured. To put this into perspective, 3 microns is around the size of a human hair thickness, but this sized particle can bring down a hydraulic system fast. Clearances between moving parts in systems are typically made for between 1 and 5 microns to pass, but it’s not always going to be the case.
How to exclude particles and moisture
Once a target for cleanliness has been identified, then it’s important to take action to ensure that these goals can be achieved. The most important areas to look at now are the exclusion of contamination and its removal. Exclusion is focused on ensuring that contamination doesn’t get into the system and removal is built around the use of filters. Keep in mind that removing contaminations can be very expensive, so a strong focus should be put onto exclusion.
Looking at how to exclude particles and contamination involves checking every step of the lubrication oil process. This includes when you receive the oil, how it’s handled, stored, dispensed and its use in the system. It’s a surprising but disappointing fact that many oils that come into a plant can actually be too dirty to use without initially going through a filtration process. Some engineers recommend that new hydraulic oil should go through a filtering process at least 5 times before they are used.
Now that you have your exclusion system and other contamination control systems in place, it’s important to measure how effective your process is. Use the ISO 4406:99 system to check to what degree your hydraulic fluid is contaminated with particles. Take samples from the machine, preferably from the actuator return lines. You may also take them from the reservoir, but taking them from there will not provide you with information as to what’s going on in the rest of the system.
In summary, the reliability of any hydraulic system is dependent upon its levels of contamination. By keeping it clean you can decrease problems. Once any hydraulic system is contaminated it will lead to trouble and expense. It’s possible to control contamination in the most challenging of environments by using this simple three step process.
Keeping overheads low is a fundamental of good money management in business. When your supervisor tells you that the company are pulling in its purse strings and he wants you and your department to help, it’s might not always obvious as to how you can cut back on costs, in particular in this day and age of expensive parts and fuel.
One approach is to save on fluid. Although your hydraulic system may not even be leaking, if you could keep your oil in service longer than usual, whilst not putting your machine at risk of damage, then you know you’re going to be his favourite employee this month.
Here’s how to do it:
Keep it inside
The most important thing is not to waste it. Although you may have a couple of slow leaks that are on your list to be fixed at some point, they are costing you more as every day goes by. The price of oil might be lower than it was, but it’s still pricey. Solving leaks comes complete with a cost reduction. If you don’t attend to them, then you’re affecting your department’s economy.
Keep it responsive
Keeping your oil within optimal operating temperatures offers many advantages. For one, it’s going to have a longer life. By allowing it to get just 10 degrees warmer, it will not have an extended life according to Arrhenius's Law. There will be negative reactions including oxidation. This is caused by air entering the system and hydrolysis – the presence of water. The warmer the oil, the more you’ll suffer from these.
In order to illustrate this – consider what happens when you have cooking oil at home. You could pour it into a cup and leave it on the side. It will take a long time to change colour. However, if you put it into a frying pan and heat it as hot as you can, you’re soon going to have a pan of darkened oil.
Some oils have anti-oxidant additives added. In addition you may want to consider installing a heat exchanger, increasing the number of filters and magnetic plugs and even going so far as replacing any copper or brass tubings under circumstances where the pressure rating is more than 10 bar.
If you do opt to use magnetic plugs, then ensure that there is regular cleaning of them. Otherwise the particles may be dislodged by any oil surge and then they will be back circulating around your system and causing damage. In addition, using the magnetic plugs will help to reduce the work of the filter.
Keep the water out
Water can damage oil. It can also compromise any additives in it. Take ZDDP which is an anti-wear additive, add water to it and you’ll find that it’s completely unstable.
Keep it clean
It’s difficult to keep hydraulic oil clean. Every time you access the system there is a chance that it will collect dust particles. It’s also likely that particles are building up from wear inside the machine. Certain metals are worse than others when it comes to increasing how fast hydrolysis and oxidation happen. These metals include iron, copper, lead and zinc in addition to water. It’s also likely that particles will attach themselves to any additives in the oil, which will lead to depletion of the additives.
In summary, gaining extended longevity from your hydraulic oil comes from good maintenance; keeping your machine leak-free, keeping oil at optimal temperature and clean. Don’t change it until the oil has degraded or your additives have extensively depleted.
Performing maintenance often and well will keep you in the good books of your boss. There’s nothing better than good filtration and the prevention of impurities to keep the fluid clean. You may also want to look at your oil storage system prior to oil being entered into the system. For example, keeping oil barrels horizontal can protect them from water collecting near the bungs. It will also mean that the bung is kept wet and therefore will be more effective as an airtight seal.
Let us know how you get on and if you have tips to share on improving hydraulic system economy, do tell.
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