Filter Presses

A filter press is a piece of equipment used for solid-liquid separation. It operates by pumping a slurry (a mixture of solids and liquids) into a series of filter plates lined with filter cloths. As pressure is applied, the liquid passes through the cloths and exits the press, while solids are retained to form a dry filter cake. The series of filter plates creates a closed volume in which the filtration process occurs, ensuring efficient separation and containment of solids.

Filter presses are one of the most efficient and cost-effective methods for separating solids from liquids. They produce a high solids content in the filter cake, offer consistent filtration quality, and are ideal for a wide range of industries including mining, chemical processing, food and beverage, and wastewater treatment.

The moisture content of the filter cake depends on the material being filtered and the type of press used. Standard chamber filter presses typically achieve residual moisture levels of 30–40%, while membrane filter presses can reduce moisture content to 15–25% due to their additional squeezing capabilities.

A chamber filter press uses fixed-volume chambers to dewater the slurry through filtration. A membrane filter press includes flexible membranes that can be inflated to apply additional pressure, squeezing out more moisture from the cake. Membrane presses are typically used when lower residual moisture is required.

Feeding pressures typically range from 7 to 15 bar (100 to 225 psi), depending on the type of press, the material being filtered, and the desired dryness of the cake. Membrane filter presses can use even higher pressures during the squeeze phase.

We always recommend using a piston diaphragm pump with our filter presses. Unlike air-operated systems, which first consume energy to compress air before generating pressure, piston diaphragm pumps convert electrical energy directly into hydraulic pressure. This results in greater energy efficiency, lower operational costs, and more consistent performance—especially important in demanding filtration processes.

Filter cloths should be cleaned regularly—either manually or with an automatic cloth washing system—depending on the process and solids buildup. They typically need to be replaced when they show signs of blinding (loss of permeability), damage, or if cake release becomes inconsistent. In general, cloth lifespan can range from several months to a year or more, depending on use.

Filter plates should be cleaned periodically to prevent solids buildup, which can lead to poor sealing and leakage. They should be replaced if they become cracked, warped, or if the sealing surfaces are damaged. Regular inspection during maintenance will help identify early signs of wear.

A solid preventative maintenance routine includes:

• Regular inspection of cloths and plates for wear or damage
• Checking for leaks or abnormal pressure drops
• Cleaning filter cloths and plates
• Lubricating moving parts
• Monitoring pump and hydraulic system performance
• Verifying plate alignment and press closure force
• Ensuring that all filtrate holes on the filter plates are not clogged, as blockages can prevent filtrate from exiting efficiently and compromise performance
• Scheduling weekly visual checks and more thorough monthly inspections is a good practice.

Leaks typically occur when there is poor sealing between plates. Common causes include:

• Worn or damaged filter cloths
• Misaligned plates
  Debris on sealing surfaces
• Insufficient closing pressure
• Warped or cracked plates
• Regular cleaning and proper plate alignment during setup are key to preventing leaks.