Application — High-Temperature Filtration
Hot Oil & Polymer Melt Filtration
Viscous media that can only be filtered hot, at pressures that punish every weak point in the element. We engineer the fabric, the construction and the confection together.
Three Loads at Once
Hot oil and melt duties are unusual because three loads arrive together. The temperature attacks the polymer. The viscosity drives the differential pressure up at any given fineness. And the pressure needed to move a viscous medium through a cake loads the fabric, the seams and the support mechanically at exactly the moment the polymer is at its weakest.
This is why a fabric that performs well in a hot but thin liquid can fail immediately in hot oil at the same temperature. Selecting on temperature alone leaves out the two loads that actually break the element.
The fourth factor is what happens when the plant stops. A medium that solidifies in the weave turns the next start-up into a pressure shock. Where shutdowns are routine, the flushing and heat-up procedure belongs in the specification.
Typical Duties
What We Optimise For
In viscous hot media the usual priorities shift. These are the objectives that decide whether an element survives the duty.
Polymer to Real Temperature
Continuous and peak temperature, and whether water or steam is involved. Dry hot oil and hot wet washing lead to completely different material decisions.
Open Area vs. Fineness
Viscosity multiplies differential pressure. We look for the coarsest construction that still meets the clarity target, and use a support layer rather than an ever finer single cloth.
Cake Release & Low Anchoring
A smooth, monofilament or PTFE surface gives a viscous, tacky cake fewer points to hold onto — and makes flushing before shutdown far more effective.
Seam and Support Strength
The seam is the pressure-limiting component. Thread material, seam position outside the main load path and a matched support layer are part of the design.
Solidification Behaviour
What the medium does in the pores when the line cools, and what the start-up procedure then demands of the fabric.
Element Format & Fixing
Pressure leaf, filter press, candle, bag or cut part — the format and the fixing method determine what construction is realistic at all.
What We Need to Specify the Element
Hot viscous duties are engineered per case. The more of this we have, the less guesswork goes into the proposal.
Related Topics
High-Temperature Filtration
The hub page: polymer limits, dry vs. wet heat, confection and cost logic.
Learn MoreSpecialty Fabrics — PEEK, PPS, PTFE
The high-performance polymers with temperature and pH data.
Learn MoreWax Filtration
The closely related duty where cake release decides the economics.
Learn MorePressure Leaf Filter Cloths
A common element format for hot oil polishing duties.
Learn MoreFilter Press Cloths
Chamber and membrane press cloths, including high-temperature polymers.
Learn MoreFabrication & Confection
Seams, welding, hardware and support layers for hot elements.
Learn MoreFrequently Asked Questions
Which filter fabric is suitable for hot oil filtration?
It depends on the temperature and on whether water is present. Up to roughly 90 °C polypropylene remains a robust and economical choice. In dry hot oil, polyester works to considerably higher temperatures, and aramid extends the mechanical strength at heat. Above that, or where steam and hot washing are part of the cycle, PPS, PEEK and PTFE are the realistic options. The construction matters as much as the polymer: viscous media need adequate open area, or the differential pressure alone will destroy the element.
Why does high viscosity change the fabric selection?
A hot oil is filtered hot precisely because it is unmanageable when cold. But even hot, viscosity is orders of magnitude above water, so the same fineness produces a far higher differential pressure. That pressure has to be carried by the fabric, the seams and the support. In practice this pushes the selection towards stronger yarns, more open constructions and, where fineness is genuinely required, towards a support layer rather than towards an ever finer single cloth.
Can filter fabrics be used for polymer melt filtration?
For melt duties the load is extreme: high temperature combined with high pressure and a medium that solidifies on cooling. Textile solutions here are always special constructions — typically PEEK or PPS, often in combination with a metal support, and with the confection designed so that no seam sits in the main pressure path. This is engineering per case, not a catalogue item, and we discuss feasibility openly before quoting.
What happens to the fabric when the line cools down?
Solidification inside the weave is one of the most under-estimated failure mechanisms in hot media. The medium sets in the pores, and the next start-up drives differential pressure straight through the fabric before it has re-melted. Where a plant is shut down regularly, the flushing and heat-up procedure is part of the fabric specification — and a smooth, low-anchor surface such as PTFE or monofilament pays back here.
What do you need in order to recommend a fabric?
Medium and viscosity at filtration temperature, continuous and peak temperature, operating pressure, machine type and element format, solids content and particle size, the required filtrate clarity, the flushing and cleaning procedure including its temperature, and the current fabric with its observed failure pattern. Where the duty allows it, a sample trial with two or three graded qualities is the fastest route to a robust selection.
A hot, viscous duty that keeps destroying elements?
Send us the medium, the temperature, the pressure and your current fabric — we will propose a polymer, a construction and a confection built for the real load.
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