By Senjie Filter Press Engineering Team · Last updated: 2026-09-10
Quick answer: A membrane filter press works in three stages: (1) slurry is pumped into closed chambers at 0.6-1.6 MPa to form cake, (2) a flexible membrane on each plate is inflated with air or water at 1.5-2.0 MPa to squeeze the cake further, and (3) plates open for cake discharge. This extra squeeze stage cuts cake moisture by roughly 10-15 percentage points versus a standard chamber press.
The whole cycle runs under hydraulic closing pressure of 20-25 MPa, which keeps the plate pack sealed while feed and squeeze pressures act inside the chambers. Below is a stage-by-stage breakdown of how a membrane filter press processes a batch of slurry from start to finish, followed by the buyer questions that come up most often when specifying one.
What are the stages of a membrane filter press cycle?
A membrane filter press cycle has five distinct stages: plate closing, feeding, membrane squeezing, air blowing (optional), and cake discharge. Each stage has its own pressure and duration, and skipping or shortening any of them directly affects final cake dryness.
- Plate closing: The hydraulic cylinder closes the plate pack against a fixed head at 20-25 MPa closing pressure, sealing every chamber before feeding starts.
- Feeding: A diaphragm, screw, slurry, or ceramic piston pump forces slurry into the chambers at 0.6-1.0 MPa for standard duty, or up to 1.6 MPa for high-pressure applications, building the cake against the filter cloth.
- Membrane squeezing: Once the chambers are full and flow slows, compressed air or water is injected behind each membrane at 1.5-2.0 MPa, mechanically compressing the cake from both sides.
- Air blowing (optional): Low-pressure air is blown through the cake to displace residual moisture in the pore spaces, used mainly for chemical or mineral cakes where extra dryness matters.
- Discharge: The hydraulic cylinder retracts, plates separate (manually, semi-automatically, or fully automatically with a plate-shifting mechanism), and cake drops or is scraped off.
Why does the membrane squeeze reduce cake moisture so much?
The membrane squeeze reduces moisture because it applies mechanical pressure directly and evenly across the entire cake face, something feed pressure alone cannot do once the cake has already formed. Feed pressure pushes liquid through a growing cake layer, but once the cake is thick enough it resists further flow no matter how long feeding continues.
The membrane solves this by acting like a hydraulic press on each finished cake slab. Because the pressure is applied uniformly, even cakes with uneven initial thickness get compressed to a consistent final moisture level. This is the main reason membrane presses are chosen for tailings, sludge, and mineral concentrates where cake moisture directly affects transport and disposal cost.
How does membrane plate construction differ from a standard recessed plate?
A membrane plate has a rigid polypropylene core plate identical in outline to a recessed chamber plate, but with an elastomer or reinforced polypropylene membrane bonded or clamped over each face. Standard plate sizes at Senjie run 320, 470, 630, 800, 1000, 1250, 1500, 1800, and 2000 mm, with plate thickness of 25-40 mm and a chamber depth of 25-32 mm before squeezing.
The membrane itself flexes into the chamber space during squeeze, reducing effective chamber volume and pushing residual liquid out through the filter cloth. Because the membrane sees repeated flexing under pressure, its material and bonding quality determine service life more than the core plate does; the plates are covered in more detail on Senjie’s filter plate product page.
What feed pumps work with a membrane filter press?
Membrane filter presses commonly run with air-operated diaphragm pumps, progressing cavity (screw) pumps, slurry pumps, or ceramic piston pumps, chosen by slurry abrasiveness and required feed pressure. Diaphragm pumps suit lower-solids, less abrasive feeds and simple installations; progressing cavity pumps handle higher-viscosity sludge at steady flow; ceramic piston pumps are preferred for abrasive mineral tailings needing consistent high pressure over long cycles.
Pump selection affects cycle time as much as press design does, because an undersized pump extends the feeding stage and delays the point at which membrane squeezing can start. Senjie’s diaphragm pumps, progressing cavity pumps, slurry pumps, and ceramic piston pumps are matched to press size during quotation.
Membrane vs. chamber filter press: what changes at each stage?
| Cycle stage | Chamber (recessed) press | Membrane press |
|---|---|---|
| Feed pressure | 0.6-1.0 MPa (up to 1.6 MPa) | 0.6-1.0 MPa (up to 1.6 MPa) |
| Additional squeeze stage | None | 1.5-2.0 MPa, air or water |
| Typical cake moisture | 40-55% | 20-35% |
| Typical cycle time | 1-4 hours | 30-90 minutes |
| Chamber depth | 25-32 mm fixed | 25-32 mm, reduced by squeeze |
Why buy a membrane filter press from Senjie?
Senjie is a China-based manufacturer of chamber, membrane, plate-and-frame, and fully automatic filter presses, founded in 2014 and exporting to 40+ countries across Southeast Asia, India, Africa, the Middle East, and Latin America. The company also produces the filter plates, filter cloth, and feed pumps used with its presses, so a full solid-liquid separation line can be specified and quoted as one package rather than sourced from multiple suppliers.
For buyers comparing options, Senjie’s full filter press range and chamber filter press lines are documented separately, with typical FOB China price ranges available on request as indicative figures — request a quotation for a firm price against your slurry data sheet.
Frequently Asked Questions
Can a membrane filter press replace a chamber filter press?
Yes, in most applications. A membrane filter press uses the same plate-and-frame arrangement as a chamber press but adds a flexible membrane on each plate face, so it produces drier cake (often 10-15 percentage points lower moisture) and a shorter cycle. The tradeoff is higher equipment cost and a hydraulic squeeze system to maintain.
What is the squeeze pressure in a membrane filter press?
Squeeze pressure is typically 1.5-2.0 MPa, applied to the back of the membrane by compressed air or water after the feed pumping stage ends. This is separate from the hydraulic closing pressure (20-25 MPa) that keeps the plate pack sealed shut.
Does a membrane filter press need a bigger feed pump?
No. Feed pressure requirements (0.6-1.0 MPa, up to 1.6 MPa for high-pressure duty) are similar to a standard chamber press, because the membrane squeeze happens after feeding stops, not during it. Pump sizing depends more on slurry solids content and required cycle time.
How much drier is membrane-pressed cake compared to chamber-pressed cake?
Chamber presses typically leave 40-55% moisture in the cake, while membrane presses on the same slurry commonly reach 20-35%, a reduction of roughly 10-15 percentage points. The exact figure depends on particle size, feed concentration, and squeeze time.
Ready to spec the right press or component for your application? Contact Senjie’s engineering team for a free sizing recommendation and an indicative quotation.