May Maintenance Tip of the Month: Focus on Filter Plate Maintenance

In this blog, we will be providing key maintenance tips for Filter Plates, particularly in conjunction with Filter Press Cloth Changeouts. But before we dive into the recommended maintenance details, first we will review the overall layout of a typical Filter Plate.

Micronics recommends being vigilant about filter press cloth changeouts and Filter Plate maintenance to ensure the efficiency and effectiveness of your Filter Press operation. We say it again and again but it is worth repeating: Routine inspections, cleaning, and filter press maintenance will prolong filter cloth life, filter plate life, and also provide you with the best filter press performance, whatever your industry.

Filter Plate Layout

In general, a filter plate consists of a sealing edge and the plate web. This layout is independent of the filter plate type, e.g. recessed chamber filter plate or membrane filter plate.

Small “pips” are present on the surface of the plate web, forming an area where the clear liquid (filtrate) can discharge once it passes through the filter cloth. The solids are captured on the filter press cloth and form the filter cake whereas the filtrate passes through the cloth, is collected between the pips, and then flows to the filtrate discharge holes. The high filtration pressures used with recessed and membrane filter plates work very well with the pipped design, providing excellent support for the filter press cloth, allowing filtrate to discharge along the base of the plate with the least resistance.

The filtrate is discharged via the filtrate discharge holes and filtrate discharge channels to the corner ports. These corner ports form a collection channel across all filter plates, collecting the filtrate and guiding it out of the filter press. Stay Bosses on the plate web provide mechanical stability and control flexing of the filter plate during delivery of the feed slurry.

Regardless of the size or style of the filter plates that your press uses, proper maintenance of your filter plates is a very important ingredient to your filter press operation!

Filter Plate Maintenance Tips

Dan Murphy, Field Service Manager

Dan Murphy is very pleased to share some tried and true tips for proper Filter Plate Maintenance.

1. Inspect the sealing surfaces for solids buildup and remove solids from the filter cloths daily using non-metal cake scrapers. Micronics offers a full array of filter cloth accessories including non-metallic cake scrapers in our product line-up to ensure the efficacy of your filter press operation, extending the efficacy of our filter press cloth. Remember that plastic spatulas/cake scrapers work best!
2. Micronics recommends that all filter plates should be fully pressure-washed at each Filter Cloth change-out. We suggest using a 2,500 – 3,000 psi pressure washer to thoroughly clean the sealing surfaces, web area, filtrate ports, and filtrate discharge ports. During cloth change-out, a medium bristle brush can be used in all filtrate porting areas. Use a non-metallic cake scraper to remove any filter cake build up on the plate’s sealing surfaces.  Clean sealing surfaces will minimize the slurry spraying from between the filter plates and will ensure that the filter plate stack and filter press frame remain square.
3. Remember that the plate’s sealing surfaces must be kept clean and free of debris! Keeping the plate’s drainage pips clean and free of debris will ensure maximum flow across the face of the filter plate web. Additionally, the plate’s filtrate discharge holes and filtrate discharge channels must be kept clean to maintain flow and help create evenly-formed filter cakes. Keeping the corner ports clean will help to maintain proper filtrate discharge from the entire filter plate stack. As noted above, Micronics recommends the use of a medium bristle brush to remove any excessive solids build-up on the plates.
4. Stay Bosses should be inspected for damage and any solid build-up removed. Excess solids can be removed with a pressure washer and medium bristle brush. In addition to removing excess solids, take proper care to also inspect the base of each stay boss for cracks which can result in plate failure. It is important to replace any filter plate with damage to the Stay Bosses!
5. Plates may become cracked, warped, or broken and do need to be replaced from time to time.  While it is difficult to prescribe the precise number of plates to keep as spares, we are pleased to work with you on an optimal spare parts program for your filter press operation. Things do happen with regard to filter plates and filter press cloth – even with the most stringent maintenance schedule – and we want to ensure that you have the spares on-hand to avoid press downtime. Contact us to discuss a proper spare parts program. At Micronics, we don’t give you a one size fits all answer.
6. Membrane Filter Plates should be cleaned in the same manner as Recessed Chamber and Companion Filter Plates in a mixed pack. With Fixed Membrane Plates, the hinge point of the plate should be inspected for cracking. If the Fixed Membrane Plate is cracked or damaged, it must be replaced. Replaceable Membranes must be fully seated in the plate groove to avoid leaking during the membrane squeeze step. Micronics recommends that you carefully inspect the membrane for damage, cracking, and/or dry rot.
7. Before simply removing a damaged plate or plates, please ensure that the hydraulic cylinder has enough throw to properly clamp the plate stack. Removing filter plates without replacing them will shorten the overall length of the plate stack. The hydraulic cylinder will only extend to a certain dimension (each press may be different). If the plate stack is too short, the cylinder will dead head, reach its limit, before applying the proper pressure to the plate stack. Leaking between the filter plates will happen during the feed cycle.  Remember to pay attention to proper sequencing of filter plates – 1-3-1-3 sequencing. Plates must be removed in pairs to perform proper post-filtration steps such as proper air blow and or cake wash.

Contact the team at Micronics to help you in optimizing filter press performance with the industry’s best filter press cloth, filter plate solutions, filter press service & parts expertise, and complete filter press systems…in short, Total Engineered Filtration Solutions. Whatever your press size, we can assist you with replacement filter plates in 470mm, 630mm, 800mm, 1000mm, 1200mm, 1500mm, 2m x 2m, and additional custom-sized filter plates. We look forward to working with you on maintaining your spare parts inventory and helping you optimize your filter press operation.