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In our latest blog we take a look at desiccant breathers and explain why they are used and how they work to maximise the efficiency of a hydraulic units breathing system.
The desiccant breathers main role is to protect a power units breathing system and filter out moisture and contaminants drawn in from the working environment, thus helping to prolong the life and efficiency of the power unit.
How does it work? – The desiccant breather unit contains silicone based gel which helps prevent particulate entering the system during operation. They also work to soak up any moisture that is in the system while it is in shut down or during a service period.
In environments where there are high ambient levels of humidity, such as offshore oil rigs, optional breathers with check valves are available which come in the necessary fitments for most power units.
Where is it fitted? – The desiccant breather replaces the unit’s standard OEM breather cap, coming in a screw-on fitment and in a number of different sizes depending on your type of hydraulic system.
How do I make sure I choose the right filter? – Many leading suppliers of desiccant breathers have product configurators on their site so you can choose from a number of crucial variables that are tailored to your system:
Airflow - which typically varies from 0-27CFM, giving a good pointer as to the amount of air that typically passes through the breather system during operation
Unit dimensions – Including height and diameter measurements to ensure the breather fits the unit without coming into contact with other parts or compromising unit space
Amount of silica gel needed – This is largely dependent on the size of the system and working environment as to how much silica gel is needed to stop particulate contamination and excess moisture accumulation
Absorption capacity – typically measured in fluid ounces, this capacity can change due to the nature of the application and the environment it is situated in
Operating temp – The filters are built to withstand large temperature fluctuations, so it is common to see operating temperatures range from around -40°C to 149°C which covers a wide range of operational and environmental conditions
Filter efficiency – An average sized desiccate breather is able to achieve in the region of 0.3µ absolute (β₀.₃≥200) efficiency under normal operating conditions.
Build quality – As technology is constantly evolving, filters are being built to withstand obstacles such as unit vibration and impact protection, and constant development is enabling filters to withstand harsher environments and temperature changes (as detailed above) with stringent product testing taking place.
With bespoke hydraulic units that use these breathers on applications such as offshore oil rigs, where humidity and other factors can potentially hamper a unit’s performance, it is imperative that the breather unit can tackle these obstacles in an effective manner.
Connections – Desiccant breather filters typically use a UN female thread to connect to a power unit with various sizes of this connection being available dependent on application.
At Hydraproducts we frequently rely on the efficiency and reliability of desiccate breather filters for our bespoke offshore power units. So feel free to contact us to learn more.
As well as the different varieties of pump, the size, operational pressure and speed also play big parts in the level of noise generated from a pump. Even small differences from pump to pump like the number of gear teeth and their geometry may emit a different pitch level.
The helical toothed pump was originally developed in Italy and comprises of a Continuum pump which contains teeth that are in constant contact with one another which means the pumps sound level sits at an impressively low 52 dBA.
As the teeth are in contact with one another at all times, the common sound of gear teeth meshing is alleviated thus reducing noise levels and ensuring that flow levels stay consistent throughout the pump. This is achieved by the redesign of gear teeth, changing their size and angle as to ensure constant contact.
As we mentioned above, typical mechanical pump noise commonly originates from grinding gear teeth but due to the pumps hydraulic function, the turbulence of hydraulic fluid travelling through the pump can also contribute to noise levels with fluid getting trapped between gear teeth and also flow pulsation. Cavitation can also cause noise and has the potential to damage the interior structure of the pump.
In this blog we will be investigating hydraulic lifts; how they operate and why they are a cost effective, reliable alternative to other forms of lift power.
Along with traction lifts, hydraulic lifts are a popular choice for residential, corporate and construction applications and have a number of benefits over their traditional traction based counterparts.
As with any type of lift, hydraulic based lifts need to be maintained at regular intervals to ensure they operate reliably and effectively. Oil is a key part of the hydraulic set up as it is pumped from a purpose built oil reservoir through a hydraulic cylinder to operate the piston, which, in turn propels the lift. Oil cleanliness is paramount for this operation and is recommended to be checked at regular service intervals.
The key working components, i.e. the pump and oil reservoir are often situated in a machine room, commonly found in the near vicinity of the lift itself. This enables easy access for any maintenance engineer to check that things are working correctly with the lift and its components.
Operating the lift – In order for the lift to work correctly, the lift piston, which sits below the lift enclosure itself and controls its movement, must work in harmony with the oil that is pumped into the cylinder which controls the piston itself.
In order to get the lift to rise, the pump valve will need to be in the closed position, thus pushing the oil from the reservoir into the cylinder. The effects of gravity then come into play and the piston is pushed up, raising the lift in the process.
To lower the lift the opposite takes place, where the pump valve is opened and the oil is released back into the oil reservoir, thus allowing the piston, and the lift, in turn, to lower.
Advantages of using Hydraulic Lifts – Firstly, using a hydraulic lift will work out cheaper than its traction based equivalent, as it uses less components. There are no cables to set up along with other parts of machinery which are commonly situated above the lift shaft itself. This makes it a cost effective solution in general if a person is looking to meet a tight budget.
Speaking of cables, another advantage hydraulic lifts have is that they don’t rely on cables to operate making them a safer equivalent; if something were to go wrong with a hydraulic lift, it would lower at the same speed as the oil leaving the cylinder, thus reducing the likelihood of sudden drops.
If space is a key issue then hydraulic lifts are ideal as their main machinery is typically situated to the side of the lift in a machine room, as mentioned at the start of the blog. This leaves the lift shaft itself free from any space consuming machinery, which ultimately aids in the planning process.
At Hydraproducts, we specialise in a range of power packs and units that are suitable for lift applications and to support this, we have recently opened our Component Division, which offers a range of components from hydraulic pumps to cylinders to fit your bespoke unit. Feel free to browse the rest of our website to find out more about our products.
If you’re curious about how hydraulic cylinders work, then you could find this post to be interesting. Let’s take a look at these powerful components that make it possible to move and lift the heaviest of items with ease.
You may not have ever considered this before, but what do you think deploys those huge wheels that aircraft need to land? They are put away tidily throughout a flight, and then when they’re approaching Heathrow, out they pop and all at the pilot’s press of a button.
Landing gear is operated through a hydraulic system. As with any hydraulic system, there are pipes, cylinders and of course hydraulic fluid. The fundamentals of this are the same as with any hydraulic system. When force is applied at one point, it is transmitted to another through the use of incompressible fluid.
Hydraulic cylinders mostly come in parallel pairs that are of differing diameters and are connected by a pipe. The cylinders will be at right angle to the pipe. This arrangement is then filled with a hydraulic fluid such as oil until the cylinders are partly filled.
The space that is left in the hydraulic cylinders will enable the pistons to operate. In one cylinder, the piston will be smaller than in the other. Fluid will be pushed into the chamber of the small piston and when force is applied, it will push the fluid into the chamber of the big piston as it will be incompressible fluid. This will then move the big piston. Due to the difference in size, the effect of the small piston’s movement will be multiplied. So for example if a small piston has a downward force applied to it of 100 lbs – the force on the big piston will be 900 lbs.
Hydraulic cylinders remove the need for a rigid structure when it comes to transferring force between two different points. This can be used to the hydraulic system’s designer’s benefit and a number of twists and turns can be added to the system. For example, there might be a space constraint. Using the different cylinders at different sizes, it’s possible to create a system that will pull, push or even lift heavy weights.
Although the hydraulic systems that are used in our everyday life are not built with cylinders quite as basic as what’s described above, they are fairly similar. Let’s look at the different components involved:
· Cylinder barrel
· Piston rod
· Cylinder bottom (Cap)
· Cylinder head
· Cylinder bottom connection
· Rod glands
There are two different main types of hydraulic cylinders used. The tie rod type of cylinders and the welded body type. The former are used when there is a need for heavy-duty industrial or commercial use. Some are small bore and others large bore. The welded body cylinder type has no steel rods in it. The top of the barrel of the cylinder is welded directly onto the object that is expected and designed to move. Although these cylinders are small in size, they are used in a surprisingly large number of different machines. In some cases it’s necessary to use a telescoping hydraulic cylinder where the piston rod will retract into the barrel of the cylinder.
Hydraulic power has really evolved over the last 50 years or so. Much of the progress has come from the aeronautical industry, surprisingly. Although hydraulics have been used since before the time of the first recorded history, it’s only now that they have really come of age and have made such a tremendous difference to us in so many fields.
ROVs are also known as remote operated vehicles and are used most often in the offshore oil and gas industries.
ROVs are the type of vehicles that most of us find somewhat exciting as a concept. Imagine – some people are lucky enough to spend their entire day playing with, sorry controlling - a small submarine from aboard a boat or a floating platform or oil rig. The vehicle is equipped with a camera so that they can see where the vehicle is, its surroundings and get clear vision of any tasks that need to be performed. The ROV is connected to the surface by what is known as an umbilical.
The ROV may sound like an autonomous underwater vehicle (AUV) but the difference is the umbilical. It’s also often described as an underwater robot. Although they may weigh as much as 5 tonnes in the air and be as large as 2 metres x 3 metres x 2 metres in height, they can be controlled by monitoring and controlling equipment including hydraulic powered winches.
ROVs are designed to be neutrally buoyant once they are in the water as they are expected to be able to move underwater and perform as requested by their operator up on the surface.
Although most ROVs in service are being used for oil and gas extraction activities (95% of them) there is another 5% that is tasked with diamond mining and undersea cable maintenance.
As far as operators go, there are most likely around 500 ROV operators working and around 1000 observation class vehicles – otherwise known as OBSROVs. Together they make jobs for between 5,000 and 8,000 workers across the planet plus another 500 or so involved in their manufacture. In addition there are companies such as us who are involved in the peripheries by producing components such as hydraulic power packs that are used for winching these machines in and out of the water.
35% of operational ROVs are located in the North Sea, with more interest for their use developing further afield in countries such as China, Brazil, Australia and the Far East. The depth of the water they work in is as much as 3,000m or 10,000ft.
The ROV is an exciting piece of marine related technology that is capable of performing a wide range of tasks and is making waves in a number of industries.
Overcentre valves can be described as a type of pilot assisted relief valve, with the only difference between the two being the check valve will open fully when sufficient pressure is applied with pressure in the cylinder port being the only restrictive force, whereas the overcentre valve has to overcome force from the spring mechanism which is reduced by load pressure.
There are 3 main areas of load based functions the overcentre valve provides, which are applicable to both rotary and linear load motion. These areas comprise:
Controlling load – This involves the valve ensuring that the actuator doesn’t run ahead of the pump, thus reducing the risk of cavitation by controlling load induced energy and preventing loss of control.
Ensuring load safety – This safety measure controls movement and ensures that load is under control when a component malfunction occurs, such as a hose failure.
It also ensures that people, equipment and property remain safe when heavy machinery is used, such as a crane with a boom, which has the potential to cause substantial damage if control is lost.
Holding load – Working with the directional valve when it is situated in the neutral position, the load holding function of the overcentre valve prevents any movement of the load and also prevents leakage past the directional valve while it is the closed position.
Pilot ratios explained
When a system is in the design stage, pilot ratios are a main factor that needs to be taken into account as different systems will benefit from different pilot ratios. For example, a system that runs stable, constant loads will normally use a high pilot pressure, while a low, unstable load will benefit from a lower pilot pressure.
The pilot open pressure drop is a good measure of system performance and efficiency, as system pressure typically runs much higher than the pilot pressure needed to open the valve fully.
The two-stage overcentre valve
An addition to the overcentre valve family, the two-stage overcentre valve aims to tackle problems that long unstable booms suffer from, especially those with large capacity cylinders such as telescopic handlers which can suffer from instability issues.
Runaway conditions are encountered in these applications when pilot valves are opened too quickly, due to heavy loads on the cylinder. The two-stage overcentre valve uses two springs with the outer spring being affected by the pilot piston with the inner used as a pressure counterbalance, thus overcoming potential instability issues.
Which type of overcentre valve should you get?
When looking for the correct overcentre valve, you have to ensure you cater for the pressures the hydraulic unit will need to work with. In a system with high back pressure a standard overcentre valve would struggle, as the standard spring chamber is vented to the valve port through the poppet, this increases relief pressure and systems which use a closed centre directional valve would run into difficulties.
Valves are now available that help to combat this problem as the relief sections of these valves are not affected by back pressure and they are identical in every other way to a standard valve.
Finally, some overcentre valves come complete with an atmospheric venting feature, which can be a beneficial feature until they are used in a corrosive type atmosphere which could cause running problems, so it is always important to check system plans and positioning when deciding on the type of valve to go for.
Hydraproducts have a comprehensive selection of valves as part of their new Components Division which can be viewed here.
Hydraulic Power Pack
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