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What we need to spec up your hydraulic filter requirements.

The Filter Guys

What we need to spec up your hydraulic filter requirements.

When looking to identify a filter housing for your specific problem we need to know a little bit about what you are trying to achieve and where in your hydraulic circuit you need to fit it. To do this we require a few key pieces of information to ensure correct fit and operation for you. That being:

Port Sizes. What size pipe-work are you fitting the housing into? In many cases this is a BSP measurement.

Operating Pressure. Is the filter operating as a return line, tank top return, pressure or suction filter, or is it simply an in-tank suction strainer?

Flow rate. What is the flow of the hydraulic oil in litres per minute?

Micron. It is important to get the micron rating correct to ensure that you are protecting delicate parts of your hydraulic system further along the flow route from damaging wear particles.

With this information we can then source and supply the correct filter unit. Contact us on 01902 491118 with your hydraulic filter enquiries or contact us via our website Online Enquiry Form.

We can also offer a range of replacement filter elements and housing indicators to help keep you informed when your filters require changing.

Hydraulic Filtration Systems and accessories.

Donaldson develops, manufactures and markets a full line of hydraulic filters for the protection of machinery and components in hundreds of applications on heavy duty mobile equipment. When you need high, medium or low pressure filters, filter housings, filter heads, replacement cartridges, spin-ons or hydraulic accessories, turn to Sterling Filtration, authorised distributors of Donaldson filters. We also offer a broad line of replacement filter elements.

Donaldson heavy duty high pressure filters sit behind pumps and other prime movers to protect critical hydraulic components such as cylinders, motors and valves. All contain our Synteq ® synthetic filter media, specially developed by Donaldson for high efficiency liquid filtration. Working pressures range from 140 to 420 bar and static pressures from 310 to 830 bar.

Donaldson Duramax ®, well known as the highest rated medium pressure filters available, are most often used in return line positions. As spin-ons, they are particularly well-suited for the duplex circuits. Donaldson Synteq ® and cellulose media are available. Duramax working pressures range from 25 to 70 bar and static pressures from 55 to 140 bar.

Low pressure filters are the most commonly used type of filters in hydraulic circuits, used most often as return line filters in applications with working pressures up to 10 bar and static pressure up to 20 bar.

An expanded line of accessories for hydraulic lines and reservoirs is also available. Finish off your hydraulic circuit with filter service indicators, pressure gauges, test point assemblies, valves, flanges, reservoir level gauges, sight glasses, a variety of tank and filter breathers, caps vents, plugs, strainers, diffusers, magnets and more.

Donaldson is proud to offer a broad selection of hydraulic replacement cartridges and spin-ons to the aftermarket via its distributors. Choose from our many different filter media to find exactly the right filter to help you meet the cleanliness requirements for your hydraulic system.

Removing water from your hydraulic system.

The Filter Guys

If you are running a hydraulic system of any kind it is important that you avoid getting water into your lubricating fluid. Water ingression causes corrosion to your hydraulic system and can lead to breakdowns and long down times for costly repairs. It is essential you take the precautions to safeguard your system by removing water from your hydraulic system.

Prevention is better than cure! Fortunately, Donaldson Filtration have the answer to the problem:

P561183 (Element) & P563268 (Head Assembly)


The SP50/60 spin-on filter is an economical, low-pressure model with a broad selection of media ratings. The die cast aluminium head and steel body ensure strength and durability – perfect for a wide variety of mobile and in-plant applications.


  • Fluid Conditioning Systems
  • In-Plant Systems
  • Mobile Equipment
  • Power Transmissions
  • Process Systems

Donaldson’s mix and match system of in-stock heads and filters allow for a speedy availability. There are a variety of media type and configuration options available and filters are interchangeable with HBK05 filters for added versatility!


  • Strong, durable die-cast aluminium head and steel body construction
  • Filters ship with a 3-seal kit containing “L”, square, and O-ring gaskets
  • Working pressure to: 150 psi/ 10.3 bar
  • Rated static burst to: 250 psi/ 17.2 bar
  • Flow range to: 60 gpm/ 227 lpm

Porting size options:

  • 1-1/4″ NPT
  • SAE-20 O-ring

Bypass ratings of:

  • 25 psi/ 1.7 bar
  • 15 psi/ 1.03 bar
  • 5 psi/ 0.34 bar
  • 2.5 psi/ 0.17 bar
  • No bypass

Available Media Types

  • Donaldson exclusive Synteq™ – synthetic fiber media for greater filtration efficiency and higher dust-holding capacity
  • Natural fibre cellulose
  • Stainless steel wire-mesh
  • Water absorbing media

If you are looking to source a hydraulic housing to remove water from your hydraulic oil, give Sterling Filtration Ltd a call on 01902 491118 for a competitive quote.


Goods and services that we offer.

The Filter Guys

Goods and services that we offer

Sterling Filtration offers a total filtration service whatever your requirements. We offer competitive prices and ongoing support to help you maintain your equipment and machinery. Engine filters for industrial and heavy machinery, agricultural machinery, heavy plant, power generators, construction equipment, mining equipment, large trucks and transporters.

  • Oil Filters (Cartridges, spin on canisters)
  • Air Filters
  • Fuel Filters (Cartridge, spin on canisters, inline)
  • Coolant Filters
  • Fuel-Water Separators
  • Fuel housings

Also we can offer hydraulic filters and housings:

  • Tank top breathers,
  • Suction filters,
  • Pressure filters inline,
  • Return line in line
  • Tank top return filters
  • Hydraulic Oil Testing,
  • Pressure differential Indicators,
  • Level gauges.

We can also offer:

  • Air intake housings including filter elements,
  • Raincaps & air pre-cleaners,
  • Air intake ducting, plastic seals/clamps/mounting bands/elbows (standard and reducing)
  • Exhaust silencers (standard and bespoke)
  • Metal exhaust pipe work/seals/clamps and mounting bands/elbows (standard and reducing)
  • Rubber charge hoses
  • Cardboard air panels
  • Metal panel filters
  • Filter bags
  • Various Filter media (cut to size or in rolls)
  • Basket strainers
  • Oil wetted air cleaners
  • Diesel Fuel Additive
  • Draper tools – filter wrenches & straps, socket sets.
  • Water housings and String Wound Cartridges.
  • A constantly updated cross referencing service.

Micron Rating. What are they and why is it important?

The Filter Guys

What is a Micron?

A micron is a measurement of size. It is one millionth of a metre (1/1000000m) or a thousandth of a millimetre (1/1000mm). In filtration, a micron rating is a rating of the media’s capacity to stop dirt (it is not an efficiency rating). The micron rating will be nominal or absolute.

A nominal micron rating means that a media may be explained as 10 micron but that is a mean average, it probably varies between 5 and 15 micron over the surface of the media itself; this often applies to cellulose media which is a natural product. Engine oil and fuel filters are often nominally rated.

An absolute micron rating means that the media has a uniformed surface and will ‘do what it says on the tin.’ A 10 micron absolute filter will not allow particles of 10.1 micron or bigger through at all. Absolute filters are man made products, such as glass fibre, and are manufactured to an extremely high specification. Hydraulic filters are often absolute rated (but not necessarily for all hydraulic applications).

Why is it important?

In filtration the micron rating of the element is very important to guarantee its correct operation. The wrong type of media can mean more dirt gets through the filter than you want and this can cause wear and tear and even complete breakdowns of your engines and hydraulic equipment.

Take a lubrication system on your engine. Oil is pumped between the moving parts of the engine, this oil contains particles, if the oil isn’t filtered before being sent into the engine then wear and tear will occur. The space between moving parts may only be 30 or 40 microns. If oil contains particles of that size then dirt is going to jam and consequently build up between moving parts. Over many hours (or years) of operation with inadequate filtration this build up of dirt will cause the moving parts to jam which will cause catastrophic failure of an engine leading to expensive downtime and repair costs.

Of course, over time filters will clog with dirt too but they are easily sourced from Sterling Filtration Ltd and replaced. They hold the damaging particles so the engine doesn’t have to. A filter may cost ten, twenty, fifty, one hundred pounds and sometimes even more, but compared to the cost of downtime of a machine and the stripping and rebuilding of an engine they are easily the most cost effective way of keeping your engines and machinery running properly all of the time. See your operators manual for service intervals.

How Filter Media Collects Particles

The Filter Guys

How Filter Media Collects Particles. There are four basic ways media captures particles.

The first, called inertia, works on large, heavy particles suspended in the flow stream. These particles are heavier than the fluid surrounding them. As the fluid changes direction to enter the fiber space, the particle continues in a straight line and collides with the media fibers where it is trapped and held.

The second way media can capture particles is by diffusion. Diffusion works on the smallest particles. Small particles are not held in place by the viscous fluid and diffuse within the flow stream. As the particles traverse the flow stream, they collide with the fiber and are collected.

The third method of particle entrapment is call interception. Direct interception works on particles in the mid-range size that are not quite large enough to have inertia and not small enough to diffuse within the flow stream. These mid-sized particles follow the flow stream as it bends through the fiber spaces. Particles are intercepted or captured when they touch a fiber.

The fourth method of capture is called sieving and is the most common mechanism in hydraulic filtration. As shown at right, this is when the particle is too large to fit between the fiber spaces.

Maximising the life of a new air/oil separator.

The Filter Guys

Some uses of compressed air are by their very nature taxing on a compressor and its engine such as sand blasting work because of the continuously changing but generally high air demands and because of the aggressive/dusty environment. In order to maximise the life of a new air/oil separator it is sensible to reflect on the following:

  • A compressor oil filter generally uses paper media capable of stopping particles 5 micron and greater in size (whereas a normal diesel engine oil filter, which may be of comparable size and identical fittings, is rated 22 micron and greater). Consequently a compressor oil filter is comparatively more expensive but for the protection it provides is should not be compromised either in specification or in maintenance change period frequency
  • The media used in an air/oil separator will stop dirt particles down to ½ micron and greater and so it can quickly be “blinded” if the compressor oil is dirty or particularly if the wrong grade of compressor oil filter is fitted
  • If dirty oil can quickly “blind” large areas of the media of the air/oil separator the velocity of the air passing through the remaining, still “open” areas has to travel that much faster. This defeats the ability of the media to cause the coalescing of the minute droplets entrained in the compressed air and significant amounts of oil can pass through and into the “work area”
  • To give any new air/oil separator a fair chance to perform satisfactorily and for the maximum effective working life it is essential to;

A. drain, flush and fit new compressor oil

B. replace the compressor oil filter making certain the correct type is used

If you have any more questions about air/oil separators, your compressor oil and replacement filters please call us on 01902 49118 for helpful advice and competitive prices.

Why should you filter your oil?

The Filter Guys

Why should you filter your oil? Often it is easy for engineers or fitters to overlook the importance of filtering the lube oil that is running through their engines or hydraulic systems. Ignoring this simple but critical issue can lead to expensive breakdowns and can even right off engines or rams. Effective application of filter elements is not only sensible but it can save you thousands of pounds over the life time of a machine or engine. Oils have to be maintained at the necessary level of cleanliness to prevent wear and tear and to return harmful particulates to the sump removing them from harms way within the engine. Regular maintenance of your oil filters provides continuous purification of your oil as well as removing the trapped particles from the system completely (upon removal of a clogged filter element).

Strainers in tanks or on scavenge hoses help avoid large debris and sediment being removed from standing tanks of oil and are easily fitted. Systems are easily modified to take advantage of the benefits a simple strainer can offer at the beginning of your lube/hydraulic oil circuit. Filter housings with take apart elements or spin on canisters can also be put into suction (between the tank and the pump) to protect the pump and can also be put into the pressure line (to help protect the engine, if lubricating oil, or protect a hydraulic ram) and are also often used in the return line (to collect any debris that may have collected from the operation of the engine or ram).

Clean oil protects your lubricating and hydraulic system from wear and breakdowns and your oil is only maintained by proper servicing and monitoring of your filtration systems. It is good practise to have a detailed maintenance schedule for all of your engines and machines.

Proper Filter Application

The Filter Guys

When selecting a new filter assembly or replacement filter, it’s important to first answer some basic questions about your application. Where will the filter be used? What is the required cleanliness level (ISO code) of your system? What type of oil are you filtering? Are there specific problems that needed to be addressed? Proper Filter Application is key.

It’s also important to think about the viscosity of the fluid in your system. In some machinery lubrication applications, for example, the oil is very thick and has a tougher time passing through the layer of media fibres. Heating techniques and the addition of polymers can make the liquid less viscous and therefore easier to filter. Another option is to install a filter with larger media surface area, such as the Donaldson W041 or HRK10 low pressure filters, that can accommodate more viscous fluids.

Next, think about duty cycle and flow issues. Working components such as cylinders often create wide variations in flow — also called pulsating flow — that can be problematic for filters with higher efficiency ratings. On the other hand, dedicated off-line filtration (also called “kidney loop”) produces a very consistent flow, so it makes sense to use a more efficient filter.

Filters used in applications with steady, continuous operation at lower pressures will last longer than filters that must endure cycles of high pressure pulsating flow. Generally, the lower the micron rating of a filter, the more often it needs to be changed since it is trapping more particles.

Finally, it’s wise to ask yourself, “How much is my equipment worth?” Calculate how much it would cost to replace the equipment in your system, in case of component failure, and make sure those areas are well protected with proper filtration. (For example, high performance servo valves are very sensitive, costly components that need to be protected with finer filtration media.)

Minimizing maintenance costs through good contamination control practices requires proper filter application based on the specific contamination problems. Good contamination control means cost effective filtration. When looking for a filter, first assess the needs of your system and any problem areas.

At Sterling Filtration Ltd we can help you to spec up the filter elements and complete units you require to achieve the level of filtration you need to protect your equipment from damaging wear and tear. Call us today on 01902 491118 and one of our experts can service your needs.

Promotional Offer: Return Line Hydraulic Housings

The Filter Guys

We are currently holding a promotional offer on two return line housings, K070030 and K040534. The offer is while stocks last. If you are interested in taking up this one time offer then give us a call on 01902 491118. Offer expires December 31st 2012.

Part No. K070030

  • Contains a nominal 10u element
  • Up to 400l per minute flow
  • Tank mounted
  • 2” BSP ported
  • Spec sheet
  • £40.00 net each.

Part No. K040534

  • Contains a nominal 30u element
  • Up to 65l per minute flow
  • Tank mounted
  • 1” BSP ported
  • Spec sheet
  • £25.00 net each.


Donaldson Lube Filters and Hydraulic Filtration.

The Filter Guys

Spin-on Filters

Donaldson durable lube filters keep your equipment running at its best to let you focus on what’s most important, getting your job done.

Donaldson Endurance Plus Additive Replenishment Technology Filters

These filters are designed for today’s emissions compliant EGR engines, use a controlled chemical release process to replenish the additives in the engine oil and deliver extended drain intervals, often double that of standard filters. These filters are a direct replacement and require no system modifications or special maintenance.

Cartridge-style Filters

Donaldson offers a complete line of cartridge-style lube filters for all makes of equipment.

Continous Product Development

Donaldson has applied its patented radial sealing technology to spin-on style lube filters. The radial seal design provides a consistent, reliable seal, enhanced structural performance and optimum protection.

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