Melt Blown Filter Cartridges

A melt blown filter cartridge is a depth filtration device made by heating polypropylene polymer, extruding it through fine nozzles, and using high-velocity air to blow the molten fibers into ultrafine strands of 1-4 microns. These fibers are collected on a rotating spindle to form a gradient structure with loose outer layers and dense inner layers — no adhesives or binders are used at any point in the process.

• Fiber fineness: 1-10 microns (most fibers 1-4 microns)
• Filtration ratings: 1µm, 3µm, 5µm, 10µm, 20µm, 30µm, 60µm
• Structure: 3-layer gradient (loose outside → dense inside)
• Material: 100% pure PP — no adhesives or binders

Melt blown filter cartridges come in 5 surface designs, each optimized for a different filtration challenge. The standard PLM-PP is the most cost-effective general-purpose option, while the grooved, orange-peel, mini-grooved, and matte types each address specific performance requirements around dirt capacity, viscosity, accuracy, and clogging resistance.

• Standard (PLM-PP): Smooth surface, general-purpose, most cost-effective
• Grooved: Slotted surface, 3x dirt capacity vs standard, lower initial pressure drop, best for high debris content
• Orange-peel: Textured surface, high mechanical strength, best for high viscosity and high solid content liquids
• Mini-grooved: Mini-grooved surface, 99% filtration accuracy, increased surface area
• Matte: PP cotton thread surface, prevents clogging, extends service life, avoids surface blockage

The gradient structure works by progressively decreasing pore size from the outer surface (loose, 10+ microns) to the inner core (dense, 1-4 microns). Large particles are captured in the outer layer, medium particles in the middle, and fine particles in the inner core — preventing surface clogging and maximizing dirt holding capacity across the full wall thickness.

1. Outer layer (loose): Captures large particles (10-50µm) — prevents surface clogging
2. Middle layer: Traps medium particles (5-10µm) — distributes particle load
3. Inner layer (dense): Captures fine particles (1-5µm) — final filtration stage
4. 3-D bridging effect: Fibers capture particles smaller than the rated pore size

PP melt blown filters resist acids, alkalis, alcohols, and acetone but are not compatible with benzene or xylene. Nylon melt blown filters handle benzene, xylene, and trichloroethylene but cannot be used with acids. The choice depends on the chemical composition of the liquid being filtered.

• Use PP for: Acidic or alkaline liquids, water filtration, pharmaceuticals, food and beverage, general pre-filtration
• Use Nylon for: Organic solvents (benzene, xylene), petrochemical applications, liquids requiring higher mechanical strength

Use melt blown for high-sediment pre-filtration where cost and dirt holding capacity are priorities. Use string wound for moderate sediment in low-viscosity liquids, especially where backwashing or high-temperature operation is needed. Use pleated filters for fine or sterile filtration requiring long service life, low pressure drop, and precise chemical compatibility.

• Melt Blown: High sediment load, RO pre-filtration, cost priority, 1-60µm, disposable
• String Wound: Moderate sediment, low-viscosity liquids, up to 250°C, backwashable
• Pleated: Fine filtration 0.1-10µm, chemical compatibility critical, long service life, sterile applications

Service life depends on the quality and particle load of the liquid being filtered. In clean tap water, melt blown cartridges typically last 3-4 months. In surface water or RO pre-filtration, expect 1-3 months. Replace when differential pressure reaches 0.2 MPa or when flow rate drops noticeably.

• Clean tap water: 3-4 months
• Surface water: 1-3 months (high sediment shortens life)
• RO pre-filtration: 2-3 months
• High plankton content: 1-2 months

To extend service life, install a coarser pre-filter (20-50µm) upstream or implement two-stage filtration for heavily contaminated water.

Melt-blowing is a polymer extrusion process where molten polypropylene is forced through fine nozzles and blown by high-velocity air into ultrafine fibers of 1-4 microns, which are then collected on a rotating spindle. Because the fibers bond thermally as they cool, the resulting structure requires no adhesives or binders — making the cartridge 100% pure PP and safe for pharmaceutical and food contact applications. The natural density variation during fiber collection creates the gradient structure automatically, without any secondary processing.

No. Melt blown filters are single-use and should not be cleaned or backwashed. Unlike string wound filters which can be backwashed up to 150 times, the gradient density structure of melt blown cartridges degrades when flow is reversed — disrupting the fiber layers, weakening thermal bonds, and risking fiber shedding into the filtered liquid. Given their low unit cost, replacement is more economical than attempting to clean them.

To maximize service intervals, install a coarser pre-filter upstream, monitor differential pressure, and replace at 0.2 MPa.

Choose your micron rating based on the particle size you need to remove and the downstream equipment you are protecting. For RO membrane pre-filtration, 5µm or 10µm is the standard starting point. For pharmaceutical or electronics applications requiring fine pre-filtration, use 1µm or 3µm. For coarse pre-filtration of tap water with visible sediment, 20-30µm is sufficient.

• 1-5µm: Pharmaceutical pre-filtration, electronics pure water, fine pre-filtration before membranes
• 5-10µm: RO membrane protection, food and beverage, general industrial water
• 20-30µm: Coarse pre-filtration, tap water with visible particles, first-stage filtration
• 60µm: Very coarse pre-filtration, high debris content, upstream of finer cartridges

When in doubt, start with a higher micron rating and work down — oversized ratings cause premature loading, undersized ratings cause rapid pressure drop.