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Imagine being able to protect your mobile hydraulic system against fluctuating temperatures. The climate in the UK is varied and some say you can have four seasons in one day. The difference between a hot summer’s day and a cold mid-winter day is extreme, even in our temperate climate.
In this post we offer 3 easy ways to get the best out of your mobile hydraulic system – even in the opposing temperatures that are found outside throughout the year.
With the hydraulic systems of today being far smaller than they once were and relied upon to run at all manner of temperatures, it’s important to provide the best hydraulic fluid to enable easy operation – in particular for mobile outdoor applications.
As an engineer, you know how important it is to avoid down time and provide the right conditions to enable best performance, including out in the field
Here are our 3 pointers on knowing what to look for when choosing the right fluid for your hydraulic system:
Viscosity index is key. VI or viscosity index is an incredibly relevant factor when looking for an oil that can handle a range of temperatures. Seek a high VI and you’ll have an oil that will not be overwrought by temperature changes.
The advantages of a high VI fluid are that it’s possible to increase overall efficiency and prevent sluggish operation in addition to reducing leakage of internal pumps. Being able to maintain optimum efficiency in a wide range of temperatures will also help with diesel consumption whilst lowering the CO2 emissions.
Low temperatures demand high fluidity. Fluidity is essential in frigid temperatures. Your oil will flow more easily and this will aid a better start-up. Using the right fluid can cut warm up by 15 to 20 mins to just 3 or 4. It will also prevent component damage from a cold start.
High temperature oil delivers protection. Equipment that runs under heavy loads and has high pressure can result in oil become thin and therefore not provide the lubrication required to protect your machine.
In review, ideally the best oil to use is an all season fluid that will provide protection throughout the year.
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..
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.
Providing all the necessary diagnostic tools to a hydraulic system technician almost guarantees that the source of an issue will be discovered and remedied rapidly. However, as with any ill, prevention is better than cure. Using the diagnostic tools on a regular basis can identify any trends that could result in the failure of a component.
Hydraulic system fluid contains many answers
Quite often, it’s the hydraulic fluid that reveals the answers as to where potential problems will arise. For example, taking a fluid sample can provide a multitude of measurements including how much of the following are in the fluid in addition to any signs of oxidation which is typical of being subjected to too much heat:
There are some tools which can make taking samples easier such as a ply and sampling valve. It also means that you won’t further contaminate your machine by adding more contaminants to it.
The value of sampling fluid regularly twinned with the fact that hydraulic equipment is usually caked in some form of dirt or dust, does not make an easy marriage. It’s essential to keep that dirt out of your system and your sample. Engineers know that sampling from hydraulic systems is a risk that engineers have to take. It’s a risk to take the sample as there is a good chance that something from the surrounding environment could enter either the system or the sample. Nobody wants dirt, particles or even water in their hydraulic system.
The risk increases when it’s necessary to draw the fluid from the hydraulic motor. Unfortunately a tube must be inserted through an open port that is accessible once an access plug has been removed. This makes it possible for contaminants to enter the system or even to stick to the tube and then be inserted directly into the fluid.
Of course, being careful will prevent contaminants from entering the hydraulic system, but it’s very important to be very careful, otherwise the fluid could be compromised.
If the environment that you keep your hydraulic system in is far from clean and dry, then you may prefer to use a sampling kit. It cuts down on the potential for contaminating the hydraulic fluid. It is not funny when you go out of your way to ensure that everything will be ok, but then realise that something must have gone wrong when you find a large particle in the system.
The sampling system is inserted into the access plug that the pump came with. Once the plug is in place, then I won’t protrude more than 1 inch, which makes it a very easy system for those who are limited to smaller space.
Then once the tap is in place, it’s easy to just unscrew the cap which will expose a cavity where you can easily take a sample from. There is then a sampling probe which will connect to the sampling valve. You’ll then find a length of clean sampling tube that connects to the vacuum pump and a clean sample bottle. Just pull on the handle to draw out fluid for adding to the sample bottle.
Taking clean samples is essential in order to take a balanced view of what’s going on with any hydraulic system. It’s possible to attain this by using one of the sampling valves that are available on the market. They create a closed loop circuit which will prevent any contamination from entering the oil sample. The sample can only be taken once the probe is fully engaged with the valve. Once the sampling probe is disconnected the sampling valve will reset.
By taking clean samples, you can discover what is going awry with your hydraulic system, and even predict potential future issues. However, if it’s not clean or you introduce further outside dirt or muck, then it’s not going to be at all helpful and you’d be better off not doing it at all. Ensure that you keep your sampling clean to promote the ‘health’ of your hydraulic system.
System performance and longevity can be greatly affected by using different viscous fluids as well as the various individual system components that can suffer reduced lifespans and early failures if the wrong fluid is used.
The size and also the structure of molecule chains are the crucial factors in measuring a fluids viscosity and the larger the molecules, the thicker the fluid.
To get around this hurdle, multi-grade fluids are used which typically have a high viscosity index and are less sensitive to temperate change than a typical monograde oil.
As lubrication is the prime objective of hydraulic fluid, it is essential that full lubrication is maintained even if temperatures fluctuate. If this does not happen, boundary lubrication is witnessed which means that only a thin layer of fluid works with system componentry, thus leading to possible friction issues and component wear.
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.
As we sympathise regularly with our readers, running hydraulic systems can be very costly. Not only can costs build rapidly from replacing damaged or worn components, but there is also system downtime to consider and to add to the expense.
If there is one deadly enemy for hydraulics, it’s contamination. In fact, contaminated fluids can be connected to more than 80% of all hydraulic failures. This includes all the related failures that can result including those of hoses, fittings, pumps and valves.
In fact, there is such a strong correlation between contamination of fluid and the lifespan of components that manufacturers of hydraulic and filtration products actually publish charts with the consequence predictions of not having inadequate filtration installed. Those systems that undergo rises in pressure will suffer from even more damage as contaminant particles make their way around the system.
Unfortunately the particles involved in hydraulic system contamination are usually far too small for the naked eye to see them. This is why it’s essential to use instruments specifically designed for contamination monitoring, otherwise a high system reliability cannot be expected to be maintained.
Although the operators and engineers who take care of industrial hydraulic systems are well aware of this problem, it’s only really coming to the fore of the mobile hydraulic system now. In this microcosm of the hydraulic world, there is still some time-based fluid maintenance going on. However, it’s becoming more apparent that this and spin-on filters are no longer enough to keep mobile hydraulic systems operating at their peak performance levels.
Quantifying contamination in hydraulic systems
Ideally every hydraulic system should have absolute filtration to capture both micro particles and those that are larger.
A Beta ratio of filtration will usually capture 99.5% of all particles that could contaminate a system. Alternatively the 1000 measurement will capture 99.9% of the particles. This will support the hydraulic system in enjoying a maximum service life. However, in addition to the Beta ratio, there are other considerations to ponder over when looking to keep the system clean.
How much dirt a filter can hold and how stable Beta ratio is will determine how well the filtration works out for the system. The best filters are usually cartridge-type that use a number of layers to help to maximise performance for all areas. Each layer will help the filter to either capture the dirt, hold it or to deliver the beta stability.
Another unexpected benefit of the cartridge-type filters is their ability to reduce how much loss of fluid there is when the filter is changed. This can keep go towards keeping costs down, whilst also lowering the impact on the environment. Although the cartridge type filter may cost more to buy, they deliver when it comes to protecting the system and cutting back on fluid loss.
With industrial hydraulic applications, cartridge filters are now considered to be the standard. They are also becoming more popular and widespread in the mobile market, which is becoming more sophisticated when it comes to components in addition to enduring rising costs.
Mobile Filtration Challenges and Solutions
Another area of concern with mobile hydraulic systems is that of space in the system to add filters and other components such as sampling valves. Quite often manufacturers will produce tank-top filters that can be integrated into the hydraulic reservoir, but sit out of the way. With global emission requirements becoming tighter, this trend is likely to accelerate in the coming years.
One issue that is unique to the mobile world is that of the cold start. It’s well known that any hydraulic fluid will thicken when sat at lower temperatures. This can increase the pressure drop for the filter element. The performance will take a downturn until the fluid begins to gain temperature and reaches the operating temperature level. Quite often the comment from an engineer will be ‘I started up and when I hit the level, nothing happened’.
Although it’s possible to install a large filter, it can add to the bulk and the cost of the system. Another work around is bypass the filter by adding in a pressure relief valve until the fluid is warmer. However, this can send contamination downstream. An approach that is less troublesome is to return the fluid to the reservoir as opposed to allowing it to circulate throughout the system.
In summary, as an engineer, the best move you can make is to identify and implement a fine filtration strategy that will enable your hydraulic system to run at its ultimate performance.
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