High pressure. Controlled filtration. Maximum protection.
Engineered for hydraulic systems requiring safe, continuous oil conditioning.
PRV-controlled performance for demanding applications.

• Suitable for systems of up to 540 litres oil
• Max input pressure 350 Bar
• Lid torque pressure 18ft lbs. 3 bolt seal
• Height: 165mm
• Diameter: 190mm
• Weight: 7.75kg
• Water Retention: 400ml
• Supplied with 1x HDFC1878kf50 Replacement Filter Cartridge
• Complete with bracket mounting kit

🔹 Why You Need This System

Hydraulic systems operate under extreme pressure, making them highly sensitive to contamination. Even small levels of particulate or moisture can lead to valve wear, reduced efficiency, and costly downtime.

The KLEENOIL HDU9778KU50HYD By-Pass Hydraulic Filtration Unit is specifically engineered to operate safely within high-pressure systems. By continuously removing contamination and water while the system is running, it maintains oil in near “as new” condition—extending oil life, improving performance, and protecting critical components.

🔹 Where It’s Used

Designed specifically for pressurised systems, the HDU9778KU50HYD is ideal for:

• Hydraulic systems and power packs
• Industrial lubrication systems
• Compressors and high-pressure oil circuits
• Gearboxes operating under load
• Mobile and industrial hydraulic equipment

It is particularly suited to applications where system pressure is high or variable, requiring controlled filtration.

🔹 How It Works

The HDU9778KU50HYD operates as a controlled bypass filtration system, incorporating a dedicated Pressure Reducing Valve (PRV) block for safe operation in high-pressure environments.

• Oil is diverted from the main hydraulic line via a bypass circuit
• The PRV block reduces pressure from up to 3000 PSI (207 bar) down to a safe filtration level (~40 PSI)
• Oil flows steadily through the high-efficiency filter
• Contaminants and water are removed
• Clean oil is returned back to the reservoir

This controlled process ensures ultra-fine filtration (down to 3 micron) and effective water removal, without affecting system pressure or performance.

🔹 Key Benefits

• Safe operation in high-pressure hydraulic systems (up to 350 bar pre-PRV)
• Removes particles down to 3 micron absolute
• Removes 99.9% water (free, emulsified, dissolved)
• Extends oil life by up to 10x in hydraulic systems
• Protects valves, pumps, and precision components
• Reduces downtime, wear, and maintenance costs

🔹 Installation (Hydraulic Integration with PRV Control)

This unit is designed specifically for bypass installation on pressurised hydraulic systems, using a controlled feed and return setup.

Typical installation method:

1. Pressure Tap-Off (Feed Line)

• Take a feed from a high-pressure point (test port or auxiliary port)
• Pressure can be up to 3000 PSI

2. PRV Block Installation

• Oil passes through the integrated PRV block
• Pressure is reduced to approx. 40 PSI for safe filtration
• Built-in relief valve protects against pressure spikes

3. Filtration Unit Connection

• Regulated oil flows into the KLEENOIL filter vessel
• Flow is controlled to approx. 4 L/min, ensuring effective filtration

4. Return Line (Low Pressure)

• Clean oil is returned to:
  • Hydraulic tank / reservoir, or
  • Low-pressure return line (<5 bar)

5. Mounting & Setup

• Install vertically using supplied bracket
• Keep hoses short and well-supported
• Ensure access for servicing and filter changes

This bypass configuration ensures continuous filtration without interfering with system operation, even in high-pressure environments.

🔹 Technical Highlights

• Filtration: 3 micron absolute (cellulose media)
• Flow Rate: Approx. 120–250 L/h (regulated ~4 L/min)
• Water Capacity: Approx. 400ml per cartridge
• Max Input Pressure: Up to 350 bar (pre-PRV)
• Operating Temperature: -20°C to +120°C
• Construction: Aluminium LM6 housing
• System Type: PRV-controlled bypass filtration
• Replacement Filter: HDFC1878KF50

🔹 Advanced System Features

• Integrated PRV block for pressure reduction and relief
• Built-in overpressure protection via spring-loaded poppet valve
• Optional sample port for live oil condition monitoring
• Designed for systems with high pulsation or variable flow
• Maintains consistent filtration without pressure disruption

🔹 Support & Application Advice

KLEENOIL UK provides a complete support service, working with you to identify the most effective filtration solution for your application. Our goal is simple—deliver consistently clean oil and long-term system performance.

Speak to our team directly on +44 (0) 1977 682810 for tailored advice.