Leaf Filter Elements

Leaf Filter Elements are the core filtration components inside vertical and horizontal pressure leaf filters. They provide the filtration surface where suspended solids are retained while clarified liquid passes through the filter media and drainage structure.

SEPARATECH manufactures and supplies Leaf Filter Elements for new pressure leaf filter systems as well as replacement, repair and rescreening applications. Our filter leaves can be customized according to filter dimensions, mesh structure, material, filtration requirements and existing equipment configuration.

Designed for industrial liquid-solid separation, our filter leaves are used in applications including edible oil, biodiesel, chemicals, brines, molten sulfur, gelatin, sugars and sweeteners, amines and other process liquids.

Vertical Pressure Leaf Filter Elements

Vertical pressure leaf filter elements are installed inside vertical pressure vessels and are commonly used where a compact equipment footprint and efficient cake discharge are required.

The filter leaves are connected to a common manifold, allowing filtrate collected from each element to flow into the outlet system.

Horizontal Pressure Leaf Filter Elements

Horizontal pressure leaf filter elements are installed inside horizontal pressure vessels and are suitable for larger filtration systems.

Horizontal pressure leaf filter systems can accommodate a large number of filter leaves and are available with different cake discharge arrangements depending on the process. SEPARATECH’s horizontal pressure leaf filter range extends to large filtration areas, with existing designs listed up to 200 m².

Multi-Layer Stainless Steel Wire Mesh

SEPARATECH manufactures filter leaves using multi-layer stainless steel wire mesh.

A typical five-layer construction consists of:

• Two outer filtration mesh layers;
• Two intermediate support mesh layers;
• One inner drainage mesh layer.

The outer mesh determines much of the filtration characteristics, while the internal layers provide support and drainage.

Reinforced Filter Leaf Keyhole Frame

The mesh pack is supported by a rigid frame to maintain dimensional stability during filtration and cake discharge.

Depending on the application, filter leaves can be manufactured using:

• Riveted construction;
• Bolted construction;
• Welded construction.

The appropriate construction depends on the filter design, operating conditions and required mechanical strength.

Filter Leaf Nozzle and Connection

The nozzle connects the filter leaf to the filtrate manifold.

The connection dimensions, nozzle configuration and sealing arrangement must match the existing pressure leaf filter.

For replacement filter leaves, these dimensions are therefore critical when determining compatibility.

What Are Leaf Filter Elements?

Leaf Filter Elements, also called filter leaves or pressure filter leaves, are rigid filtration elements installed inside a pressure vessel. A typical pressure leaf filter contains multiple leaves connected to a common filtrate manifold. During operation, process liquid is forced through the filtration surface. Suspended solids are retained on the outside of the leaves, while the filtered liquid enters the internal drainage structure and flows toward the manifold.

The filter leaves therefore perform two essential functions:

• Provide the filtration surface;
• Collect and drain the filtered liquid.

The performance of the entire pressure leaf filter depends heavily on the design, condition and construction of its filter leaves.

Plain Dutch Weave

Plain Dutch Weave is commonly used where fine filtration and high mechanical strength are required.

A commonly used configuration for pressure leaf filter applications is 24 × 110 Plain Dutch Weave.

Plain Weave

Plain weave mesh can also be supplied for applications requiring a different combination of filtration opening, permeability and mechanical characteristics.

A 60-mesh plain weave configuration is among the mesh types listed for pressure leaf filter leaves.

Reversed Plain Dutch Weave

Reversed Plain Dutch Weave, including PZ80 configurations, can be selected according to the required filtration characteristics.

The appropriate mesh should be selected based on the process liquid, solids loading, required filtrate quality and pressure-drop requirements.

Twilled Weave

Twilled Weave is a woven wire mesh characterized by its diagonal weave pattern. Compared with plain weave, the twilled structure allows finer filtration openings while maintaining good mechanical strength and stability.

Twilled Weave can be used for Leaf Filter Elements where fine particle retention, adequate permeability, and resistance to repeated pressure and cleaning cycles are required.

Customization may include:

• Overall leaf dimensions;
• Filtration area;
• Mesh type;
• Mesh layer combination;
• Wire diameter;
• Frame construction;
• Nozzle dimensions;
• Nozzle position;
• Manifold connection;
• Material;
• Sealing arrangement.

Customized filter leaves are particularly important when replacing elements in an existing pressure leaf filter from another manufacturer.

Rescreening

Rescreening replaces the damaged filtration mesh while retaining suitable structural components of the existing filter leaf.

This can be an economical alternative to manufacturing a completely new filter leaf.

SEPARATECH provides rescreening services for old or damaged filter leaves, including leaves from other manufacturers. Existing SEPARATECH information states that suitable leaves can be rescreened and inspected before reassembly.

When Should Filter Leaves Be Replaced?

Replacement or rescreening may be considered when:

• The filtration mesh is torn;
• The filter leaf is distorted;
• Filtrate clarity has deteriorated;
• Pressure drop has increased;
• Filtration cycles have become shorter;
• The leaf has suffered corrosion;
• The frame or nozzle has been damaged.

Dry Cake Discharge

In dry cake discharge systems, the filter cake is dried before removal.

Compressed air, inert gas or steam may be used for cake drying depending on the process.

A pneumatic vibrator can then be used to assist cake removal.

Wet Cake Discharge

Wet cake discharge is used when the collected solids are removed as a slurry rather than as a dry cake.

A spray device can wash the cake from the filter leaves, allowing the resulting slurry to leave through the vessel drain.

Filtration Area

The available filtration surface determines how much filter media is available for liquid-solid separation.

A properly designed filter leaf maximizes usable filtration area while maintaining adequate drainage and mechanical strength.

Filtrate Clarity

The filtration mesh and filter cake work together to retain suspended particles.

For precoat filtration, the selected mesh must also provide a suitable surface for forming and maintaining the precoat layer.

Pressure Drop

Mesh structure, cake thickness, liquid viscosity and solids loading all influence pressure drop.

Selecting a mesh solely according to nominal micron size is therefore not sufficient for every application.

Mechanical Strength

The filter leaf must remain structurally stable during:

• Filtration;
• Cake formation;
• Cake discharge;
• Cleaning;
• Repeated pressure cycles.

Edible Oil

Applications include:

• Bleaching earth filtration;
• Activated carbon removal;
• Oil clarification;
• Biodiesel processing.

Chemical Processing

Filter leaves can be used for:

• Chemical clarification;
• Catalyst recovery;
• Process liquid filtration;
• Brine filtration;
• Amine filtration.

Molten Sulfur

Pressure leaf filter elements can be used in molten sulfur filtration systems where corrosion resistance, temperature resistance and reliable mechanical construction are important.

Food and Beverage

Applications include filtration of:

• Gelatin;
• Sugars;
• Sweeteners;
• Other process liquids.

Industrial and Process Filtration

Other applications include:

• Completion fluids;
• Brines;
• Petrochemical process liquids;
• Specialty chemical filtration.

Existing Filter Model

Provide the pressure leaf filter manufacturer, model and serial number whenever available.

Filter Leaf Dimensions

Important dimensions include:

• Overall length;
• Overall width;
• Frame dimensions;
• Nozzle dimensions;
• Nozzle position;
• Leaf spacing.

Process Liquid

The process liquid determines the required material compatibility.

Important information includes:

• Chemical composition;
• Temperature;
• Viscosity;
• Corrosiveness.

Solids Characteristics

Provide information about:

• Solids concentration;
• Particle size;
• Cake characteristics;
• Required cake discharge method.

Required Filtration Performance

The desired:

• Filtrate clarity;
• Flow rate;
• Filtration cycle;
• Pressure drop;

Customized Manufacturing

Filter leaves can be manufactured according to equipment dimensions, mesh requirements, materials and process conditions.

Replacement and Rescreening

SEPARATECH supports both complete replacement filter leaves and rescreening of suitable existing elements.

Support for Existing Equipment

Replacement filter leaves can be matched using equipment information, drawings, samples and dimensions.