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If you’ve been in the hydraulic industry for some time, there’s no doubt that at some point you will have seen cloudy oil. This is what happens when there is contamination with water above the oil’s level of saturation. The definition of a saturation level is how much water can dissolve in oil – for mineral hydraulic oil this will typically be around the 200 to 300 ppm at 68 F or 20 C.
As an aside, something worth knowing is that bearing life can be increased by almost 150% if water concentration is reduced to just 25 ppm.
The more water in the oil, the more issues you’re going to face. One of our engineers recently witnessed oil that so was incredibly cloudy because it had over 10,000 ppm of water in it which actually made it more than 1% water!
Here’s what happens when there is water in hydraulic fluid:
· Either depletes or reacts with additives to form by-products that can corrode some metals
· Clogs filters by reducing filterability
· Increases ability of air entrainment
· The likelihood of cavitation increases
· Lubricating film-strength is reduced leading to corrosion and wear vulnerability
It’s also possible to spawn bacteria with water present in oil.
Measuring and Removing Water
How can you measure how much oil and how much water you have in your hydraulic fluid?
The test that is considered to be the standard laboratory method is the Karl Fischer Volumetric Regent Method which others may know simply as the Karl Fischer test. Another method sometimes used is the FTIR or Fourier transform infrared spectroscopy test. However, this is a test that can only really be considered effective with oil and water mixes that are greater than 1000 ppm of water. If you’re serious about measuring water contamination, we recommend that you go with the Karl Fischer.
Now that you know that there are some very unpleasant side effects when there is water in your oil, what are you options with regards to removing it? If you’ve got a system that has only a small volume of oil, then you may opt to change the oil. This option will most likely prove to be the most cost effective approach. For larger oil volumes, it’s best to use filters built for water removal when there is small amounts of water involved.
Water removal filters come in two types, polymeric and coalescing. The former works by using chemicals that attract water. They absorb water drops and retain them permanently. Whereas coalescing filters collect the water and put it into a collector which is drained once in a while. Water that has been dissolved will not be collected by either filter types.
Another approach to collect water is the headspace dehumidification approach. This uses the reservoir’s headspace to circulate and dehumidify the air. Water will then migrate to the headspace where it is removed by a dehumidifier.
Headspace flush is another approach that is similar to the previous method, except that it is collected by a small flow of dry compressed air that is flushed through the headspace. The dry air will pick up the water.
One more approach is to use a variation on the headspace flush by using a hygroscopic breather and then connecting a vacuum pump. This approach is reliant on a spare port located on the top of the reservoir, as distant from the breather as possible. This method does not need a source of dry compressed air.
We are in the business of supplying mobile power packs for hydraulic systems. If you want to know more about our products, browse through our hydraulic unit product pages or call us for a no obligation chat.
Businesses all over the world are now looking at how to move away from fossil fuels such as oil and our utter dependence upon them. A variety of experiments using alternative fuel are now being performed in many different areas of several industries. One of these experiments is to test whether water might be able to take the place of hydraulic oil.
Most hydraulic equipment uses oil to power the cylinders, pumps and valves that are at the core of the operations of industrial equipment such as hydraulic machines. Once the hydraulic oil is under pressure it can power the cylinders by exerting force. But is it possible that water can do the same job?
Although some hydraulic equipment has been used successfully with water, in particular for applications that require a high level of fire resistance, most hydraulics need the water to have an additive used. This then makes it possible for there to be lubrication in the machine, even if 95% of the fluid is water.
There are some exciting results coming from engineering company, Danfoss, who has been designing and manufacturing hydraulic equipment that can operate with just water. Working without any additives, this hydraulic equipment prototype is 100% green. It has made it possible for suitable components to be manufactured to support the hydraulic system.
Advantages of water hydraulics
Because water is not flammable, and it can be used for other purposes such as fire safety, it can work well. However, it operates at a much lower pressure as it’s not as viscous as oil. This means that it can transmit power far more efficiently than oil, and in a far smaller area. So it could actually be more powerful than oil when it comes to hydraulic powered activities.
As water transfers heat better, it will also mean a smaller heat exchanger than is necessary for oil.
However, because water is lower when it comes to viscosity, this could prevent an issue with greater leakage. Rubber seals would need to be used and there wouldn’t be such great lubrication, so finishes to components would need to be smooth to aid movement.
In addition, because water will easily turn to vapour, there will need to be pressurized lines into the pump. If temperatures are low, the machinery might not be able to operate as the water could freeze at a far lower temperature than oil.
Watch this space for latest news as more exploration is done in the area of replacing hydraulic oil with water.
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.
Global demand is not easing up when it comes to farming vital resources that are found in subsea environments. In fact, industries have now begun to expand their efforts and are putting more energy and effort into devising machines that are capable of delivering what is required.
With over 60% of the surface of the earth covered by water, it’s no secret that there are many resources that are awaiting exploration and development. This new frontier has a number of industries involved including oil and gas, natural science, mining, energy generation and infrastructure.
Hydraulic systems are incredibly useful to remote operated vehicles that are used underwater. They offer high power density and a reliability not found in other systems. It’s possible to use hydraulics in such a way that the vehicle is very compact and therefore it can be deployed and recovered easier.
Highly technical and complex systems need to be serviced and maintained by subsea remote operated vehicles. For example, equipment needs to be lowered and lifted to the seabed, emplaced systems need to be monitored, such as communication cables and petroleum wellheads.
Although some subsea hydraulic equipment is designed specifically for the task, in some cases, the equipment has been manufactured to a quality that can handle the high pressures and the corrosive conditions of the depths of the sea anyway and needs just a little customisation to perform at a reliable level. A major factor that is considered is the depth of the water and how that could impact the hydraulic system.
Here are other considerations that go into developing hydraulic systems for subsea operations:
Machines that operate at 1000ft below sea level are required to operate in salt water, but the water-pressure is not significantly high. Another factor that has to be catered for is that sunlight can reach up to 800ft into the water and could promote the growth of sea life over the surface of the equipment such as the cylinders and the rods.
Beyond 1000ft to as deep as 6,000ft, pressure becomes a major factor. Increasingly 14.5psi for every 10m of depth, it will be as high as 7250psi at 5000m. It’s at these depths that work is performed by subsea robots such as AUVs (autonomous underwater vehicles) and ROVs (remote operated vehicles).
Subsea vehicles aren’t typically in use for long periods of time. They will be used to accomplish tasks in electromechanically and electrohydraulic subsystems. Although they can operate beyond 100m of depth they typically won’t be submerged for long periods of time. However, they need to be ready when required and any downtime must be kept to a minimum.
Special design features may be required for components exposed to water pressures this high. For example, structural modifications may be required or pressure compensation.
These depths would normally be found a long way from shore, therefore would be operated by either ships, platforms or floating platforms. Water that is from 6000ft to 35,800ft is rarely entered unless it’s by subsea vehicles from the military or research. The conditions are so extreme, that every piece of equipment, including hoisting and tethering will need to be engineered to handle the weight and dimensions of systems at this water depth. In addition the size of the waves are larger, as are the forces brought on by maritime currents.
Ambient hydrostatic pressure is exposed to the hydraulic fluid using a pressure compensation system, with a flexible seal to prevent hydraulic fluid and seawater from making contact.
The benefits of hydraulic drives are brought into their own in these types of machines. Not only are they powerful and compact, rugged but precise, they are able to deliver power and be flexible for a wide range of tasks.
Engineers continue to work on how they can make the best of what hydraulic systems offer when it comes to subsea conditions.
It’s no secret that water can cause incredible damage to any hydraulic system.
If you’ve been a hydraulic system engineer for some time, you may have already seen a system that has cloudy oil in it. Cloudy oil is the result of having so much water in oil that it is above the saturation level. Most often the saturation level will be at 200 to 300 ppm at a temperature of 68°F or 20°C.
Going the other way on the scale, by reducing water in a system, you can increase the life of it by a significant amount. For example, by ensuring that it’s at a level that is lower than 100 ppm, the life of a bearing could be increased by 150%. (According to Timken Bearing Company in their Stauff Contamination Control Program).
If oil is cloudy, then it will have at least 200 ppm of water in it. Of course, the greater the level of water in the oil, the more issues you’ll have in terms of performance and reliability. We once had a look at a system for a client and it had more than 10,000 ppm of water which is more than 1%.
Here’s a checklist of why you don’t want water in your hydraulic fluid:
· It decreases the presence of some additives
· It reacts with some additives to make corrosive products that will attack metals
· Clogs filters
· Increases cavitation
· Increases air entrapment
· Reduces lubrication
Although if you do your own research, you may come across information that states that having 0.1% of water in your system is perfectly acceptable, according to the Timken Bearing Company report, it is far better to have as little as 0.01% of water in your hydraulic fluid as it will increase life expectancy of bearings in their case, but components etc. in ours.
If that isn’t enough information to convince you, then take note that 500 ppm of water and over can even create micro-biological contamination if you have the following elements also present:
· Food: i.e. nitrogen, carbon or phosphorous from the oil
· Oxygen: there is usually between 7 and 10% of air in hydraulic oil
· Temperature: bacterial growth can occur between 24°C and 49°C
· Low flow: the reservoir is a great place for breeding to take place
· Particles: these will help to transport and colonizing
Although you will need each of the above present to help keep bacterial growth going, water is what is behind the success of it. Therefore, keeping your oil dry is critical in stopping growth.
In this article we want to explain the ins and outs of hydraulic powerpacks. A vital piece of equipment that is used with so many machines we see every day.
In a nutshell, hydraulic powerpacks are self contained units that are used instead of a built in power supply for hydraulic machinery. Hydraulic power uses fluid to transmit power from one location to another in order to run a machine. It really is as simple as that.
So what do they look like?
In order to recognise and better understand hydraulic powerpacks, it is a good idea to get to know the key components. Hydraulic powerpacks come in many different shapes and sizes, some are very large and stationary whereas others are much smaller and more compact. In fact, some hydraulic powerpacks are so compact that they can easily be transported in a small van or even an estate car.
The only real way to identify hydraulic powerpacks is through its main components. No matter the size of the unit, all power packs will have the following; a hydraulic reservoir, regulators, a pump, motor, pressure supply lines and relief lines.
What do these components do?
It may be obvious to some but in this post we wanted to explain every hydraulic power pack component as simply as possible. So here goes.
First up is the hydraulic reservoir which quite simply holds the fluid. Reservoirs will come in different sizes.
Then we have the regulators. Regulators are vital as they control and maintain the amount of pressure that the hydraulic powerpack delivers.
Thirdly we have the pressure supply lines and relief lines. The supply line simply supplies fluid under pressure to the pump and the relief lines relieve pressure between the pump and the valves. The relief lines also control the direction of flow through the system.
Finally we have the pump and a motor. We will begin with the simpler component of the two, the motor. The motor is simply there to power the pump. Easy as that. Now the pump generally performs two actions. Firstly, it operates as a vacuum at the pump inlet and through atmospheric pressure forces fluid from the reservoir into the inlet line and then to the pump. It then delivers the fluid to the pump outlet and pumps it into the hydraulic system. We did warn you that the second part would be slightly more confusing.
So what is the function of hydraulic powerpacks?
Hydraulic powerpacks deliver power through a control valve which in turn runs the machine it is connected to. Hydraulic powerpacks come with a variety of valve connections. This means that you can power a variety of machines by using the appropriate valves.
Hydraulic powerpacks are relied upon by a range of different machines that use hydraulic power to do its work. If a machine is required to carry out heavy or systematic lifting then its likely it would need help from a hydraulic powerpack.
To make it easier for you to understand, we have included a list of trades that regularly rely on our powerpacks. On a building site you will see machines like bulldozers and excavators, which both need hydraulic powerpacks. But, it is not just on building sites that you will find these types of machines. Fishermen and mechanics both need hydraulic powerpacks too. If we did not have them then how would fishermen lift their nets or how would mechanics lift our cars?
When picking a hydraulic powerpack there are a variety of pumps and options to pick from and it is important to pick the right pack to meet your machines needs. It is also important to consider a pack that will help maximise productivity and minimise cost.
Many people will overlook the necessity of hydraulic powerpacks, but they really are vital to ensuring our society runs efficiently.
Do you need to maintain hydraulic powerpacks?
Yes you do and this is hugely important! Hydraulic powerpacks require regular maintenance to ensure they are working properly and safely and to help extend their life. Maintaining hydraulic powerpacks is relatively simple and includes checking the tubing, this can be for any noticeable problems such as dents or cracks. It is also vital to regularly change the hydraulic fluid and look at the reservoir to check for any corrosion or rust in hydraulic power packs.
What hydraulic powerpacks do we provide?
Generally we provide four different types of hydraulic powerpacks. You can pick from a standard powerpack, a mini powerpack, a micro powerpack or a bespoke powerpack.
The standard hydraulic powerpack uses a standard range of modular components and is ideal for the most demanding industrial applications. The mini powerpack is ideal for applications requiring up to 5.5kW. The micro hydraulic powerpacks were originally produced for mobility applications, so are great for when space is limited. Finally, if none of these seem to fit your needs then we offer bespoke hydraulic powerpacks ensuring your application gets the hydraulic powerpack it requires.
Finally, who is the genius behind hydraulic powerpacks?
The man behind hydraulics was Laissez Pascal. A French mathematician, physicist and religious philosopher who lived in the mid seventeenth century. Pascal made observations about fluid and pressure which led to Pascal’s law. Pascal's law states that when there is an increase in pressure at any point in a confined fluid, there is an equal increase at every other point in the container. Hydraulic powerpacks have been designed based on Pascal's law of physics, drawing their power from ratios of area and pressure.
So, interested in our Power Packs? Come on over to the main website and see what we can do for your Hydraulic Power Pack Needs .
In this week’s blog we look at how water contamination can affect hydraulic fluid, especially with the winter months approaching, where freezing temperatures can interact with system operation causing potential system damage.
If you see a cloudy build up appearing within the oil in your hydraulic power unit, this could point to water contamination and must be investigated immediately, as it shows that water has risen above the typical saturation level when mixed with oil giving a cloudy-like appearance. This saturation level comes at approximately 200 - 300 ppm at 20°C (68°F) for mineral based hydraulic oil.
Ideally, preventative measures should be taken from the outset to remove the chances of water ingress contaminating oil and this is where desiccant breathers come in to the equation. We have covered these in a recent blog and highlighted their benefits in reducing moisture entering a hydraulic power unit. The silicone gel contained within the desiccate breather soaks up any moisture present, thus helping the system to run at optimal efficiency.
Passing dry desiccant air directly through the system to dry the oil is another effective method of filtering out water and this is best carried out at approximately -40°F dew point temperature. Water ingress and moisture is most commonly found entering the system through the reservoir breather cap, so replacing the standard cap with a purpose built breather will help to alleviate this problem.
When monitoring the colour of the hydraulic oil itself to identify any potential water contamination, it is not always a warning sign if the fluid had some discolouration as this could be attributed to such things as thermal stress and oxidation, which can be commonly found in systems but still need to be monitored to rule out any other issues that may arise. This may include increased heat generated through pressure loss and component failure within the system.
It is always best to take a sample of oil and check it fully for contaminant traces so the exact cause of discolouration can be identified, as speculating and guesswork at this stage could prove to be costly.
The environment around the hydraulic power unit can play a big part in the contamination process. For example, cold temperatures and lack of proper ventilation will contribute to moisture building around the system and increase the possibility of it seeping in, so locating the hydraulic system correctly is crucial. Freezing is another big issue because if the liquid is exposed to extremely low temperatures it could cause catastrophic damage to a system, rendering it in-operational as components could seize up and cause the system to malfunction.
At Hydraproducts, we have the facilities to test if contaminants are present in hydraulic fluid; these samples are then sent off to the lab for further analysis where required to pinpoint exactly what is causing the contamination so it can be effectively dealt with. We always test our hydraulic power units fully before they reach our end customer, to ensure that they are in optimal running condition prior to their first use in an application.
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