Factors to consider when choosing a Filter Press
Once the cubic foot capacity of the filter press has been determined the next step is, the proper selection of the size of the filter plates, frame, components and any accessories. This will allow you to see exactly where the cu. ft. capacity fits in relation to the volume of each size press. For example a 5 cu. ft. can be sized as a 470 mm, a 630 mm and also an 800 mm. The size selected is determined by the amount of expandability desired. After the plate size is selected, there are many options from which to choose. The following information is a summary of what needs to be considered in order to make the proper selection, Please read each section in turn and note your requirements.
Select the type of filter plate material. The standard material is an industrial grade polypropylene. An optional FDA approved food grade polypropylene material and a high temperature glass filled polypropylene material are also available. Special materials are also available such as Carbon Steel , Stainless steel and Kynar. Contact us for availability of special materials.
The standard is a 100 psi recessed gasketed plate with EPDM seals. Viton seals are available as an option. Also available are non-gasketed plates with quick removal latex edged cloths, where the cloth acts as the gasket. The Non gasketed plates allow for easier change out of the filter cloth, are lower in cost, but are not completely liguid tight during the processing stage. Membrane filter plates have an inflatable bladder that allows the filter cake to be squeezed to further dry the filter cake. A “full pack” is where every plate is a membrane style and “mixed pack” is where every other filter plate is a membrane style. Membrane presses require an additional diaphragm power pack.
Optional Backing Plate
If a shorter cycle is desired, when running low volume applications for example the capacity of the filter press can be temporarily reduced. This is done by moving the follower (tail) plate forward in the plate stack next to a three button plate. The backing or "blank plate" is then placed behind the follower plate acting as extra support. The follower plate will not flex or break when used in this manner.
Plate and Press Pressure Rating
The 100 psi design is standard for most dewatering applications and will produce a cake with approximately 30-35% solids. A 225 psi design can be used to provide an increased yield per cycle and depending on the application can increase the solids in the cake to 50% or more.
The 32 mm cake thickness is standard. Options include 25, 38 and 50 mm cake thickness. 25 mm would be used for high viscosity (slimy) materials and 50 mm would be used for easily filtered material.
There are four options for filter cloths to be used in the filter press. PMU (5 micron) is standard in the press and is suitable with most applications. The PSM material (50 micron) is for coarse filtration. The PMM (10 micron) is a special fiber that resists oily and tacky solutions. The FTW material (1 micron) is for high clarity applications. Check your particle size and submit a sample of the material to us for testing to determine which cloth will be suitable.
There are two different frame configurations. Sidebar, and a dual I-beam overhead design. The standard design is sidebar construction. All presses up to 1000 mm come only in sidebar design. The 1200 mm and the 1500 mm are available in both designs. 1500 mm x 2000 mm and 2000 mm size presses only come in dual beam overhead designs. Automatic cloth washing is only available in overhead designs.
Volume of Plates/Expansion Spacer
All filter presses are available with optional removable expansion spacer. On presses ordered with a spacer, the first number denotes current plate capacity. The second number in the nomenclature is the maximum capacity the frame will allow. The size of the expansion spacer is the difference between these two numbers.
A pump controller loads the press filter cavities in a progressive manner that improves the filterability, and ultimately the dryness of the filter cake. This option is available on all filter presses.
On automatic closure filter presses (630 mm and larger) the control panel can be mounted on the right side (standard) or left side (optional). If a plate shifter is included with a press its operation is from the same side as the control panel.
Discharge/Air Blow-down Piping
The discharge/air blow-down piping is available in either manual or in automatic operation in any of materials listed. The standard is Schedule 80 PVC with EPDM seals. An optional core blow-down is available to purge the center feed line of residual fluid. Available materials of construction are schedule 80 PVC, Steel and Stainless Steel.
The feed style can vary for special applications such as pharmaceuticals and some type of food processing. Center feed is standard, however a choice of any corner feed is available.
Automation versus Manual OperationManual or semi automatic operation requires input from an operator to start and operation of the filter press, including opening and closing, blow down, plate shifting etc. Fully automated presses require initial start up of operation and then close fill, blow-down, plate shift, discharge and cloth wash is automated. Restarting the press cycle still requires operator input.