A rubber filter press is a mechanical device that applies pressure to a material using a specialized filtration medium, allowing liquids to pass through. It is a commonly used solid–liquid separation equipment. First employed in chemical production in the early 18th century, it continues to be widely utilized across industries such as chemicals, pharmaceuticals, metallurgy, dyes, food processing, brewing, ceramics, and environmental protection.

　　The rubber filter press features stable plate performance, convenient operation, and enhanced safety and ease of use. Its metal extrusion cylinder is machined from seamless steel tubing, while the plastic‑steel filter plates are precision‑cast, capable of withstanding high temperatures and pressures, ensuring long-lasting durability.

　　What is the working principle of a rubber filter press?

　　The hydraulic pressure system of the pressure filter comprises a hydraulic power unit, a cylinder, a piston, a piston rod, and a half‑clamp connecting the piston rod to the pressure plate. The hydraulic power unit consists of a motor, an oil pump, a relief valve (pressure regulator), a directional control valve, a pressure gauge, oil lines, and an oil tank.

　　Filtration methods: The two primary types of filtration are surface filtration and sub‑surface (or dead‑end) filtration. In surface filtration, a water cone forms beneath each filter plate, and the filtrate flows out directly from this cone. In sub‑surface filtration, each filter plate is equipped with a drainage channel, and the outlets of multiple plates are connected via a common discharge passage, which empties through a pipe attached to the outlet on the thrust plate.

　　Washing methods: When the filter cake requires washing, options include unidirectional and bidirectional washing, as well as submerged‑flow unidirectional and bidirectional washing.

　　How is a rubber filter press installed and commissioned?

　　1. The filter press shall be installed on a level concrete foundation. At the feed end, the thrust plate anchor bolts shall be securely fastened to the foundation. At the frame end, after installing the base bolts or anchor bolts, secure them with two nuts, leaving an appropriate gap between the nut washers and the frame to allow for slight tensioning. Prior to final positioning, the installer must verify that the crossbeam and the large flat surface of the thrust plate are perfectly vertical.

　　2. The foundation structure shall be designed by a structural engineer based on the equipment’s load requirements, and it is recommended that anchor bolts be installed in double‑drilled holes.

　　3. Sufficient operating and maintenance space must be provided around the filter press, and the hydraulic pressure filter must be installed in an appropriate location to ensure the proper functioning of the hydraulic station.

　　4. In accordance with operational requirements, properly arrange the filter plates, supply lines, washing lines, and drainage pipes. Equip the system with a filter pressure gauge and a return line to regulate filter pressure. For membrane‑pressurization type units, install a compressed air pipeline.

　　5. For hydraulic filter presses and hydraulic stations, fill the oil tank with clean No. 20–40 hydraulic oil, operating at a temperature range of –5°C. If ambient temperatures are low, select a hydraulic oil with similar viscosity and a lower pour point. The hydraulic oil must be filtered through an 80–100 mesh filter.

　　6. For mechanical or hydraulic compression devices, the motor should operate normally upon startup. The hydraulic pressure gauge should rise smoothly, and the hydraulic system must show no signs of leakage. Adjust the hydraulic station’s operating pressure appropriately according to the machine model’s size. If, after testing the machine, the oil tank is found to be low on oil, replenish it promptly.