Hydraulic Systems, Control Elements and the Filter Press
The type of hydraulic system best suited for a dewatering application typically depends on the size of the filter press required. Three common types of filter press hydraulic systems include air-operated, electric and manual.
Filter press controls are a factor of both the type of hydraulic system that will be utilized, as well as other specifics such as the options for automated valves, drip trays, an automatic plate shifter, and/or an automatic high pressure cloth washing unit. Various manifold processes can also be more easily facilitated by the use of proper controls, such as Air Blow, Even Fill, Pre-Coat, Acid Wash, Core Blow, Cake Wash, and more.
M.W. Watermark’s team of filter press experts can work with you to determine the best hydraulic system, controls, and other options for your particular dewatering project. Retrofits are also available.
Air-Operated Hydraulics and Controls
For filter press sizes 630mm through 1000mm, air hydraulics are included as standard.
How does an air-powered hydraulic pump work?
For added operator and equipment protection, the hydraulics are enclosed within the leg of the filter press that supports the hydraulic cylinder. 100 psi air is used to pressurize an oil reservoir that is used to push the plate stack closed. Once the plate stack is closed, a high pressure air-operated hydraulic pump clamps the plate stack with a force, plus a safety factor, to counteract the pressure of the slurry feed.
Air-powered hydraulic pumping units convert plant air to hydraulic pressure through a simple ratio system that uses a large air piston area at low pressure to produce a high hydraulic pressure on a small area hydraulic piston. Automatic reciprocation is controlled by the action of a pilot operated selector valve in the pneumatic section of the pump.
As the hydraulic output approaches the desired pressure dictated by the air pressure regulator setting, the pump slows down and finally stalls when the hydraulic force balances the air force. Hydraulic force is maintained with no consumption of power.
When the cycle is complete, the air-operated hydraulic system releases the pressure within the cylinder and uses air pressure to retract the follower for filter cake discharge. The air hydraulic control switches and gauges are mounted in either the left or right hand side of the leg of the filter press to suit the installation.
Click to visit our Filter Press Hydraulic Systems webpage and watch a video overview of our air operated hydraulic system – demonstrating its functionality including closing, clamping and opening times.
What control options are available for an air-operated hydraulic filter press?
Visit our Filter Press Controls webpage to learn more.
Electric Hydraulics and Controls
For filter press sizes 800mm through 1500mm, electric hydraulics are optional to decrease filter press opening and closing times.
How does an electric-powered hydraulic pumping unit work?
Electric-powered hydraulic pumping units maintain the hydraulic pressure, and if the pressure exceeds the relief setting this pressure is vented – keeping the pressure within the specified range.
For added operator and equipment protection, the hydraulic power unit (HPU) is enclosed within the leg of the filter press that supports the hydraulic cylinder. The HPU includes a high volume / low pressure pump to open and close the plate stack quickly and a low volume / high pressure pump that clamps the plate stack. Once the plate stack is closed, the high pressure hydraulic pump clamps the plate stack with a force, plus a safety factor, to counteract the pressure of slurry feed.
Electric hydraulics are controlled by the M.W. Watermark Electric Hydraulic Control System (EHCS), which monitors the status of the system and provides an emergency stop push button, disconnect switch, and touch screen control of the filter press hydraulics.
Learn more about the M.W. Watermark Electric Hydraulic Control System (EHCS).
Manually-Operated Hydraulics and Controls
A manual hand pump to extend the spring return hydraulic cylinder is standard for the 470mm filter press.
How does the manually-operated hydraulic pump work?
The hydraulic cylinder is swung from the “up” to the “clamp” position and the hand pump is operated to build clamping pressure. At the end of the dewatering cycle, the hydraulic pressure is released and the cylinder is retracted by an internal spring. The cylinder is then lifted to the “up” position and the follower is manually pulled back to the end of the press. The filter plates are then manually shifted to discharge filter cake.
This option requires hands-on “pumping” to get the job done. However, when working with a smaller filter press such as the 470mm, or when an air supply or electrical power is not available on the job site, manually-operated hydraulics may be the best solution.
Note: To eliminate the requirement of pumping by hand, an air-operated single-acting closure system (for closing only) is available as an option.
Click to watch a video on our Hydraulic Systems webpage on how to open/close a manually-operated hydraulic filter press.
Contact an M.W. Watermark Sales and Service Team member to learn more.
About M.W. Watermark
M.W. WATERMARK wants to make a difference. We are passionate about the world’s water. We are innovative, focused on customer service and always try to exceed expectations. We are an environmentally conscious company with people who are energized, encouraged and inspired to make a difference on our planet by helping to keep our shared, finite water supply clean and usable for generations to come. We build amazing, custom water and wastewater treatment equipment. Together, we can make a difference.