JWI Filter Press Sizing & Capacity Guide

When discussing filter press sizing, engineers typically refer to capacity in cubic feet of filter cake volume.

For example:

• 1 cubic foot filter press
• 10 cubic foot filter press
• 50 cubic foot filter press
• 100 cubic foot filter press

This capacity represents the total chamber volume available between the filter plates.

A larger chamber volume allows the press to hold more solids before reaching the end of the filtration cycle.

In general:

Larger capacity = longer cycle time but fewer cycles per day.

Smaller capacity = shorter cycle time but more cycles per day.

Proper sizing balances production requirements with operating efficiency

JWI manufactured filter presses using several standard plate sizes.

Plate SizeT

ypical Capacity Range470 mm1–5 Cubic Feet630 mm3–15 Cubic Feet800 mm10–40 Cubic Feet1000 mm25–75 Cubic Feet1200 mm50–150 Cubic Feet1500 mm150–300+ Cubic Feet

The plate size determines the surface area available for filtration.

Larger plates provide:

• Greater filtration area
• Larger chamber volume
• Higher throughput capacity
• Reduced number of filtration cycles

Many municipal and industrial facilities operate 1000 mm, 1200 mm, and 1500 mm presses due to their ability to process larger sludge volumes.

 Many JWI model numbers contain valuable sizing information.

Examples include:

470G-32-5-1

1200NG-32-83-100

The model number generally identifies:

• Plate size
• Gasketed or non-gasketed design
• Cake thickness
• Number of plates
• Cubic foot capacity

A model such as:

1200NG-32-83-100

indicates:

• 1200 mm plates
• Non-gasketed configuration
• 32 mm cake thickness
• 83 plates
• Approximately 100 cubic feet of chamber volume

For a detailed breakdown of model numbers, see our JWI Model Number Guide.

 Proper sizing starts with understanding the sludge being processed.

Important design information includes:

How many gallons must be processed each day?

Examples:

• 500 gallons per day
• 5,000 gallons per day
• 50,000 gallons per day

The daily volume establishes the overall capacity requirement.

The solids concentration dramatically impacts filter press sizing.

Examples:

• 2% solids
• 5% solids
• 10% solids
• 20% solids

Higher solids concentrations typically generate more filter cake per gallon processed.

How many hours per day will the filter press operate?

Examples:

• 4 hours per day
• 8 hours per day
• 16 hours per day

Longer operating windows may allow a smaller press to meet production requirements.

 Some applications prioritize maximum throughput while others require the driest possible cake.

Cake dryness influences:

• Cycle length
• Feed pressure
• Air blowdown requirements
• Overall throughput

This is one of the most common questions asked by operators.

Unfortunately, there is no universal answer.

Filter presses are batch devices and throughput depends heavily on sludge characteristics.

As a very rough guideline:

Filter Press SizeTypical Throughput Range

1 Cubic Foot100–500 Gallons/Day5 Cubic Foot500–2,500 Gallons/Day10 Cubic Foot1,000–5,000 Gallons/Day25 Cubic Foot5,000–20,000 Gallons/Day50 Cubic Foot10,000–50,000 Gallons/Day100 Cubic Foot20,000–100,000 Gallons/Day

Actual performance depends on:

• Sludge type
• Solids loading
• Polymer effectiveness
• Feed pressure
• Filter cloth selection

These values should be considered general engineering estimates only.

 Many engineers focus only on cubic foot capacity.

In reality, cycle time often has a larger impact on plant performance.

A smaller press completing multiple cycles per shift may process more sludge than a larger press with excessively long filtration cycles.

Cycle time includes:

• Filling
• Filtration
• Air blowdown
• Plate opening
• Cake discharge
• Press closing

Optimizing cycle time often provides significant improvements without replacing equipment.